N-acetylcysteine (NAC) is an acetylated form of the amino acid L-cysteine. It has antioxidant and anti-inflammatory properties and is a mucolytic agent, meaning that it helps break down mucus in the respiratory tract.<a href="#ref-3" id="ref-link-3" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Gerry K Schwalfenberg. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34221501" target="\_blank" rel="noopener noreferrer"&gt;N-Acetylcysteine: A Review of Clinical Usefulness (an Old Drug with New Tricks)
&lt;/a&gt;&lt;/p&gt;J Nutr Metab (2021 Jun 9)&lt;/div&gt;'>[3]</a> NAC is converted to L-cysteine after ingestion, which, in turn, is converted into glutathione (GSH), a powerful antioxidant. 
L-cysteine can’t be supplemented on its own because free L-cysteine is highly unstable, becoming readily oxidized in solution which can encourage the formation of insoluble precipitates.<a href="#ref-4" id="ref-link-4" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;A L SHEFFNER. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/13977050" target="\_blank" rel="noopener noreferrer"&gt;The reduction in vitro in viscosity of mucoprotein solutions by a new mucolytic agent, N-acetyl-L-cysteine
&lt;/a&gt;&lt;/p&gt;Ann N Y Acad Sci (1963 Mar 30)&lt;/div&gt;'>[4]</a> Similarly, glutathione is rapidly broken down in the gastrointestinal tract and blood, limiting its availability in the body when supplemented directly.<a href="#ref-5" id="ref-link-5" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Forman HJ, Zhang H. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34194012" target="\_blank" rel="noopener noreferrer"&gt;Targeting oxidative stress in disease: promise and limitations of antioxidant therapy.
&lt;/a&gt;&lt;/p&gt;Nat Rev Drug Discov (2021-Sep)&lt;/div&gt;'>[5]</a> In contrast, NAC is more stable and has a much lower toxicity than free L-cysteine,<a href="#ref-6" id="ref-link-6" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;S M BIRNBAUM, M WINITZ, J P GREENSTEIN. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/13479126" target="\_blank" rel="noopener noreferrer"&gt;Quantitative nutritional studies with water-soluble, chemically defined diets. III. Individual amino acids as sources of non-essential nitrogen
&lt;/a&gt;&lt;/p&gt;Arch Biochem Biophys (1957 Dec)&lt;/div&gt;'>[6]</a><a href="#ref-7" id="ref-link-7" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Vered Gazit, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/12957221" target="\_blank" rel="noopener noreferrer"&gt;Long-term neurobehavioral and histological damage in brain of mice induced by L-cysteine
&lt;/a&gt;&lt;/p&gt;Pharmacol Biochem Behav (2003 Jul)&lt;/div&gt;'>[7]</a> making it safer and more effective for increasing cysteine and glutathione levels in the body.

What is N-acetylcysteine?

NAC seems to have a direct mineral chelating effect, meaning it can bind tightly to certain minerals and aid in their removal from the body. In rodents, decreased tissue accumulation and increased urinary excretion of lead has been observed following NAC supplementation,<a href="#ref-21" id="ref-link-21" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wang L, Wang Z, Liu J. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20097726" target="\_blank" rel="noopener noreferrer"&gt;Protective effect of N-acetylcysteine on experimental chronic lead nephrotoxicity in immature female rats.
&lt;/a&gt;&lt;/p&gt;Hum Exp Toxicol (2010-Jul)&lt;/div&gt;'>[21]</a> and in humans, a reduction in serum lead has been found.<a href="#ref-22" id="ref-link-22" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kasperczyk S, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/23731375" target="\_blank" rel="noopener noreferrer"&gt;The administration of N-acetylcysteine reduces oxidative stress and regulates glutathione metabolism in the blood cells of workers exposed to lead
&lt;/a&gt;&lt;/p&gt;Clin Toxicol (Phila) (2013 Jul)&lt;/div&gt;'>[22]</a> Standard oral doses of NAC appear to be protective against lead toxicity in humans, possibly related to a reduction in lead accumulation in the body and reducing oxidative stress.
Lead is a heavy mineral that can be toxic to the human body. Exposure to lead causes oxidative stress in the body, which seems to deplete both cellular and enzymatic antioxidants, including glutathione.<a href="#ref-23" id="ref-link-23" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Dobrakowski M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/27331344" target="\_blank" rel="noopener noreferrer"&gt;Glutathione, glutathione-related enzymes, and oxidative stress in individuals with subacute occupational exposure to lead.
&lt;/a&gt;&lt;/p&gt;Environ Toxicol Pharmacol (2016-Jul)&lt;/div&gt;'>[23]</a> NAC is thought to alleviate the toxic effects of lead by aiding in its removal from the body while also acting as a building block for the synthesis of new glutathione.<a href="#ref-21" id="ref-link-21" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wang L, Wang Z, Liu J. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20097726" target="\_blank" rel="noopener noreferrer"&gt;Protective effect of N-acetylcysteine on experimental chronic lead nephrotoxicity in immature female rats.
&lt;/a&gt;&lt;/p&gt;Hum Exp Toxicol (2010-Jul)&lt;/div&gt;'>[21]</a><a href="#ref-24" id="ref-link-24" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Nehru B, Kanwar SS. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20020952" target="\_blank" rel="noopener noreferrer"&gt;Modulation by N-acetylcysteine of lead-induced alterations in rat brain: reduced glutathione levels and morphology.
&lt;/a&gt;&lt;/p&gt;Toxicol Mech Methods (2007)&lt;/div&gt;'>[24]</a>
In animal studies, NAC has shown protective effects (assessed by biomarkers in serum and histopathological examination) against lead toxicity in the kidneys,<a href="#ref-21" id="ref-link-21" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wang L, Wang Z, Liu J. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20097726" target="\_blank" rel="noopener noreferrer"&gt;Protective effect of N-acetylcysteine on experimental chronic lead nephrotoxicity in immature female rats.
&lt;/a&gt;&lt;/p&gt;Hum Exp Toxicol (2010-Jul)&lt;/div&gt;'>[21]</a> the brain,<a href="#ref-24" id="ref-link-24" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Nehru B, Kanwar SS. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20020952" target="\_blank" rel="noopener noreferrer"&gt;Modulation by N-acetylcysteine of lead-induced alterations in rat brain: reduced glutathione levels and morphology.
&lt;/a&gt;&lt;/p&gt;Toxicol Mech Methods (2007)&lt;/div&gt;'>[24]</a><a href="#ref-25" id="ref-link-25" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ercal N, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/8818630" target="\_blank" rel="noopener noreferrer"&gt;In vivo indices of oxidative stress in lead-exposed C57BL/6 mice are reduced by treatment with meso-2,3-dimercaptosuccinic acid or N-acetylcysteine.
&lt;/a&gt;&lt;/p&gt;Free Radic Biol Med (1996)&lt;/div&gt;'>[25]</a> and liver tissue.<a href="#ref-25" id="ref-link-25" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ercal N, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/8818630" target="\_blank" rel="noopener noreferrer"&gt;In vivo indices of oxidative stress in lead-exposed C57BL/6 mice are reduced by treatment with meso-2,3-dimercaptosuccinic acid or N-acetylcysteine.
&lt;/a&gt;&lt;/p&gt;Free Radic Biol Med (1996)&lt;/div&gt;'>[25]</a> In workers with high levels of occupational lead exposure, oral supplementation of 200–800 mg of N-acetylcysteine daily for 12 weeks reduced blood concentrations of lead and improved markers of oxidative stress.<a href="#ref-22" id="ref-link-22" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kasperczyk S, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/23731375" target="\_blank" rel="noopener noreferrer"&gt;The administration of N-acetylcysteine reduces oxidative stress and regulates glutathione metabolism in the blood cells of workers exposed to lead
&lt;/a&gt;&lt;/p&gt;Clin Toxicol (Phila) (2013 Jul)&lt;/div&gt;'>[22]</a>

Does N-acetylcysteine help with lead toxicity?

NAC has shown positive effects on parameters of both male and female infertility.
NAC may improve sperm health and quality (e.g., motility, concentration, morphology, volume) in infertile men, likely through reductions in oxidative stress in the testicular tissue and semen. However, NAC hasn’t consistently been found to influence hormones involved in male fertility (<a href="/outcomes/testosterone/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Testosterone&lt;/h6&gt;&lt;p&gt;Testosterone is the best-known androgen (male hormone), but females produce it too. In both sexes, low testosterone can reduce libido and cause fat gain, muscle loss, and bone loss.&lt;/p&gt;&lt;/div&gt;">testosterone</a>, <a href="/outcomes/luteinizing-hormone/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Luteinizing Hormone&lt;/h6&gt;&lt;p&gt;Luteinizing hormone (LH) is a hormone that is secreted from the pituitary and is known to regulate fertility and stimulate testosterone production from the testicles. Its increase is thought to promote testosterone (somewhat unreliably).&lt;/p&gt;&lt;/div&gt;">luteinizing hormone</a>, follicle stimulating hormone (FSH), and <a href="/outcomes/prolactin/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Prolactin&lt;/h6&gt;&lt;p&gt;Prolactin is a peptide hormone that is known to regulate lactation in women and is a negative regulator of steroid hormones (estrogen and testosterone) when it is highly elevated.&lt;/p&gt;&lt;/div&gt;">prolactin</a>).<a href="#ref-26" id="ref-link-26" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Zhou Z, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33405232" target="\_blank" rel="noopener noreferrer"&gt;The role of N-acetyl-cysteine (NAC) orally daily on the sperm parameters and serum hormones in idiopathic infertile men: A systematic review and meta-analysis of randomised controlled trials.
&lt;/a&gt;&lt;/p&gt;Andrologia (2021 Mar)&lt;/div&gt;'>[26]</a>
In women with infertility due to polycystic ovarian syndrome (PCOS), NAC may reduce <a href="/outcomes/testosterone/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Testosterone&lt;/h6&gt;&lt;p&gt;Testosterone is the best-known androgen (male hormone), but females produce it too. In both sexes, low testosterone can reduce libido and cause fat gain, muscle loss, and bone loss.&lt;/p&gt;&lt;/div&gt;">testosterone</a> and increase follicle stimulating hormone levels.<a href="#ref-27" id="ref-link-27" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Zahra Shahveghar Asl, Karim Parastouei, Eslam Eskandari. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36597797" target="\_blank" rel="noopener noreferrer"&gt;The effects of N-acetylcysteine on ovulation and sex hormones profile in women with polycystic ovary syndrome: a systematic review and meta-analysis
&lt;/a&gt;&lt;/p&gt;Br J Nutr (2023 Jan 4)&lt;/div&gt;'>[27]</a> Compared to placebo, NAC seems to increase <a href="/outcomes/rateofpregnancy/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Rate Of Pregnancy&lt;/h6&gt;&lt;p&gt;Rate of pregnancy refers to the success rate for getting pregnant. It is generally calculated as a percentage of all insemination events that lead to pregnancy within a given menstrual cycle.&lt;/p&gt;&lt;/div&gt;">pregnancy</a> and <a href="/outcomes/ovulation/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Ovulation&lt;/h6&gt;&lt;p&gt;Ovulation is the release of eggs from the ovaries and occurs approximately two weeks before the menstrual period begins. Ovulation marks the end of the follicular phase of the menstrual cycle and the beginning of the luteal phase.&lt;/p&gt;&lt;/div&gt;">ovulation</a> rates, but not when compared to metformin (a medication commonly used in PCOS).<a href="#ref-28" id="ref-link-28" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Song Y, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31749393" target="\_blank" rel="noopener noreferrer"&gt;Comparison of the efficacy between NAC and metformin in treating PCOS patients: a meta-analysis.
&lt;/a&gt;&lt;/p&gt;Gynecol Endocrinol (2020-Mar)&lt;/div&gt;'>[28]</a>

Does N-acetylcysteine affect fertility?

Many mental disorders are associated with dysregulation of the neurotransmitters <a href="/foods/glutamate/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Glutamate&lt;/h6&gt;&lt;p&gt;Glutamate is a neurotransmitter produced by the body that plays an important role in learning, memory, and brain development. It is an amino acid found in many foods, most commonly as &lt;em&gt;monosodium glutamate&lt;/em&gt; (MSG), including tomatoes, cheese, mushrooms, seaweed, and soy.&lt;/p&gt;&lt;/div&gt;">glutamate</a> and/or <a href="/outcomes/dopamine/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Dopamine&lt;/h6&gt;&lt;p&gt;Dopamine is a catecholamine and neurotransmitter that can be measured in the blood, and changes in response to the diet or nutritional supplementation.&lt;/p&gt;&lt;/div&gt;">dopamine</a>, as well as increased levels of oxidative stress in the brain.<a href="#ref-29" id="ref-link-29" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ganesh Raghu, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33380301" target="\_blank" rel="noopener noreferrer"&gt;The Multifaceted Therapeutic Role of N-Acetylcysteine (NAC) in Disorders Characterized by Oxidative Stress
&lt;/a&gt;&lt;/p&gt;Curr Neuropharmacol (2021)&lt;/div&gt;'>[29]</a> Aside from its antioxidant effects, research shows that NAC crosses the blood-brain barrier and can directly alter glutamate neurotransmission, with an indirect effect on dopamine as well,<a href="#ref-20" id="ref-link-20" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Smaga I, Frankowska M, Filip M. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33760228" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine as a new prominent approach for treating psychiatric disorders.
&lt;/a&gt;&lt;/p&gt;Br J Pharmacol (2021-Jul)&lt;/div&gt;'>[20]</a> making it a potentially helpful supplement for a variety of conditions.
When used in addition to standard care, NAC has shown small benefits for the management of <a href="/conditions/schizophrenia/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Schizophrenia&lt;/h6&gt;&lt;p&gt;Schizophrenia is a brain condition that may cause auditory and/or visual hallucinations, delusions, difficulties with emotions and cognition, and verbal communication problems. These symptoms manifest between the ages of 16 and 30.&lt;/p&gt;&lt;/div&gt;">schizophrenia</a>,<a href="#ref-30" id="ref-link-30" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Xu X, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/35287043" target="\_blank" rel="noopener noreferrer"&gt;The efficacy of nutritional supplements for the adjunctive treatment of schizophrenia in adults: A systematic review and network meta-analysis.
&lt;/a&gt;&lt;/p&gt;Psychiatry Res (2022-May)&lt;/div&gt;'>[30]</a><a href="#ref-31" id="ref-link-31" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kishi T, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36330886" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine for schizophrenia: A systematic review and meta-analysis.
&lt;/a&gt;&lt;/p&gt;Psychiatry Clin Neurosci (2023-Feb)&lt;/div&gt;'>[31]</a><a href="#ref-32" id="ref-link-32" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Yolland CO, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31826654" target="\_blank" rel="noopener noreferrer"&gt;Meta-analysis of randomised controlled trials with -acetylcysteine in the treatment of schizophrenia.
&lt;/a&gt;&lt;/p&gt;Aust N Z J Psychiatry (2020-May)&lt;/div&gt;'>[32]</a> depression symptoms (including bipolar depression),<a href="#ref-33" id="ref-link-33" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Nery FG, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33354859" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine as an adjunctive treatment for bipolar depression: A systematic review and meta-analysis of randomized controlled trials.
&lt;/a&gt;&lt;/p&gt;Bipolar Disord (2021-11)&lt;/div&gt;'>[33]</a><a href="#ref-34" id="ref-link-34" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Fernandes BS, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/27137430" target="\_blank" rel="noopener noreferrer"&gt;N-Acetylcysteine in depressive symptoms and functionality: a systematic review and meta-analysis.
&lt;/a&gt;&lt;/p&gt;J Clin Psychiatry (2016-Apr)&lt;/div&gt;'>[34]</a> <a href="/conditions/autism-spectrum-disorder/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Autism Spectrum Disorder&lt;/h6&gt;&lt;p&gt;Autism spectrum disorder (ASD) is a neurodevelopmental condition that begins in early childhood. It affects a person’s ability to interact socially, communicate, and learn. ASD comes with varying degrees of differences, which is why it is called a “spectrum” disorder.&lt;/p&gt;&lt;/div&gt;">autism spectrum disorder</a> (specifically hyperactivity and irritability),<a href="#ref-35" id="ref-link-35" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Lee TM, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32900213" target="\_blank" rel="noopener noreferrer"&gt;Effectiveness of -acetylcysteine in autism spectrum disorders: A meta-analysis of randomized controlled trials.
&lt;/a&gt;&lt;/p&gt;Aust N Z J Psychiatry (2021-Feb)&lt;/div&gt;'>[35]</a> and <a href="/conditions/substance-use-disorder/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Substance Use Disorder&lt;/h6&gt;&lt;p&gt;Substance use disorder is an abnormal mental condition characterized by an inability to control the use of legal or illegal drugs, alcohol, or medications, leading to health issues or problems at work or home.&lt;/p&gt;&lt;/div&gt;">substance use disorder</a>.<a href="#ref-36" id="ref-link-36" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Duailibi MS, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28898494" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine in the treatment of craving in substance use disorders: Systematic review and meta-analysis.
&lt;/a&gt;&lt;/p&gt;Am J Addict (2017-Oct)&lt;/div&gt;'>[36]</a>

Does N-acetylcysteine affect mental disorders?

During physical exercise, cells produce a high level of <a href="https://examine.com/glossary/reactive-oxygen-species/">ROS</a>. While this actually serves a biological role that positively affects skeletal muscle adaptations and force production, in vitro and animal studies suggest that excessively high levels of ROS can contribute to impaired muscle function and muscle fatiguing.<a href="#ref-37" id="ref-link-37" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Reid MB. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18191753" target="\_blank" rel="noopener noreferrer"&gt;Free radicals and muscle fatigue: Of ROS, canaries, and the IOC.
&lt;/a&gt;&lt;/p&gt;Free Radic Biol Med (2008-Jan-15)&lt;/div&gt;'>[37]</a><a href="#ref-38" id="ref-link-38" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Shindoh C, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/2361912" target="\_blank" rel="noopener noreferrer"&gt;Effect of N-acetylcysteine on diaphragm fatigue.
&lt;/a&gt;&lt;/p&gt;J Appl Physiol (1985) (1990-May)&lt;/div&gt;'>[38]</a><a href="#ref-39" id="ref-link-39" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Reid MB, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/1474054" target="\_blank" rel="noopener noreferrer"&gt;Reactive oxygen in skeletal muscle. I. Intracellular oxidant kinetics and fatigue in vitro.
&lt;/a&gt;&lt;/p&gt;J Appl Physiol (1985) (1992-Nov)&lt;/div&gt;'>[39]</a>
NAC has been explored as a potential <a href="/glossary/ergogenic/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Ergogenic&lt;/h6&gt;&lt;p&gt;An ergogenic is any training technique, mechanical device, nutritional ingredient, dietary practice, or supplement that improves physical performance or enhances training adaptations.&lt;/p&gt;&lt;/div&gt;">ergogenic</a> due to its antioxidant effects, but research supporting its use is limited. A 2017 meta-analysis was unable to find any evidence of a performance benefit with NAC supplementation, but the analysis included studies using vastly different dosages, exercise regimens, and study populations (e.g., elite athletes, untrained individuals).<a href="#ref-40" id="ref-link-40" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Rhodes K, Braakhuis A. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28102488" target="\_blank" rel="noopener noreferrer"&gt;Performance and Side Effects of Supplementation with N-Acetylcysteine: A Systematic Review and Meta-Analysis.
&lt;/a&gt;&lt;/p&gt;Sports Med (2017-Aug)&lt;/div&gt;'>[40]</a> NAC seems to display the most consistent benefit when exercise is being performed in a fatigued state,<a href="#ref-41" id="ref-link-41" class="ref-link popover" data-tooltip="&lt;div&gt;&lt;p class=&quot;mb-3&quot;&gt;Cobley JN, et al. &lt;a href=&quot;https://pubmed.ncbi.nlm.nih.gov/22089305&quot; target=&quot;\_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;N-Acetylcysteine's attenuation of fatigue after repeated bouts of intermittent exercise: practical implications for tournament situations
&lt;/a&gt;&lt;/p&gt;Int J Sport Nutr Exerc Metab (2011 Dec)&lt;/div&gt;">[41]</a><a href="#ref-42" id="ref-link-42" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Slattery KM, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/24576857" target="\_blank" rel="noopener noreferrer"&gt;Effect of N-acetylcysteine on cycling performance after intensified training.
&lt;/a&gt;&lt;/p&gt;Med Sci Sports Exerc (2014-Jun)&lt;/div&gt;'>[42]</a><a href="#ref-43" id="ref-link-43" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Medved I, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/15194675" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine enhances muscle cysteine and glutathione availability and attenuates fatigue during prolonged exercise in endurance-trained individuals
&lt;/a&gt;&lt;/p&gt;J Appl Physiol (1985) (2004 Oct)&lt;/div&gt;'>[43]</a> but it may negatively affect muscle adaptations to training.<a href="#ref-44" id="ref-link-44" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Petersen AC, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21827635" target="\_blank" rel="noopener noreferrer"&gt;Infusion with the antioxidant N-acetylcysteine attenuates early adaptive responses to exercise in human skeletal muscle
&lt;/a&gt;&lt;/p&gt;Acta Physiol (Oxf) (2012 Mar)&lt;/div&gt;'>[44]</a> Ultimately, further research is needed to determine if NAC supplementation is beneficial in this context, and if so, in what setting and dosage.

Does N-acetylcysteine affect exercise performance?

Acetaminophen (paracetamol) is a widely available medication used to treat <a href="/outcomes/fever/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Fever&lt;/h6&gt;&lt;p&gt;Fever is a temporary increase body temperature above 100.4 degrees Fahrenheit or 38 degrees Celsius.&lt;/p&gt;&lt;/div&gt;">fever</a> and <a href="/outcomes/pain/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Pain&lt;/h6&gt;&lt;p&gt;Pain is the adverse sensation associated with injury, arthritis, and various forms of nerve injury that impairs well being and day-to-day living. Supplements may either universally reduce pain, or may alleviate the pain associated with a disease state.&lt;/p&gt;&lt;/div&gt;">pain</a>. It is also the leading cause of liver transplantation in the U.S. and the second leading cause worldwide due to liver toxicity that can occur with overdose. When acetaminophen is overdosed, a toxic metabolite (N-acetyl-p-benzoquinone imine (NAPQI)) begins to build up in the liver. Normally, glutathione is responsible for neutralizing NAPQI, but when glutathione levels become depleted, NAPQI begins reacting with molecules within liver cells, leading to irreversible liver cell death. NAC is an effective antidote for acetaminophen (paracetamol) toxicity primarily because it replenishes glutathione levels, but it can also directly bind to and neutralize NAPQI to minimize liver cell damage and convert NAPQI back to acetaminophen temporarily.<a href="#ref-45" id="ref-link-45" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Agrawal S, Khazaeni B. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28722946" target="\_blank" rel="noopener noreferrer"&gt;Acetaminophen Toxicity
&lt;/a&gt;&lt;/p&gt;StatPearls (2023-01)&lt;/div&gt;'>[45]</a>

How does N-acetylcysteine work for acetaminophen toxicity?

Oxidative stress describes a state of imbalance between oxidants and antioxidant defense mechanisms in the body. When oxidants (e.g., ROS, reactive nitrogen species (RNS)) outweigh the body’s natural antioxidant defenses (e.g., antioxidant enzymes, glutathione), cellular damage can occur, including damage to proteins, lipids, and DNA. This is thought to contribute to the development or worsening of a wide range of diseases.<a href="#ref-5" id="ref-link-5" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Forman HJ, Zhang H. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34194012" target="\_blank" rel="noopener noreferrer"&gt;Targeting oxidative stress in disease: promise and limitations of antioxidant therapy.
&lt;/a&gt;&lt;/p&gt;Nat Rev Drug Discov (2021-Sep)&lt;/div&gt;'>[5]</a>

What is oxidative stress?

NAC may have a role in the prevention or early treatment of hearing loss, although research is still in the early stages. 
Hearing loss is complex and can occur for many reasons, but increased levels of <a href="https://examine.com/supplements/n-acetylcysteine/faq/what-is-oxidative-stress/">oxidative stress</a> within the ear is an important contributing factor. Excessive levels of reactive oxygen species|ROS within the ear canal can damage or kill auditory hair cells — the cells responsible for converting sound vibrations into electrical signals that the brain can understand — leading to hearing loss.<a href="#ref-55" id="ref-link-55" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Chang PH, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36457967" target="\_blank" rel="noopener noreferrer"&gt;Effect of N-acetyl-cysteine in prevention of noise-induced hearing loss: a systematic review and meta-analysis of randomized controlled trials.
&lt;/a&gt;&lt;/p&gt;Arch Med Sci (2022)&lt;/div&gt;'>[55]</a>
Research suggests that NAC may reduce the risk of drug-induced hearing loss when used concurrently with potentially ototoxic drugs (i.e., drugs that are toxic to the ear, such as aminoglycoside antibiotics or cisplatin).<a href="#ref-56" id="ref-link-56" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Orgel E, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/37134194" target="\_blank" rel="noopener noreferrer"&gt;Intravenous N-Acetylcysteine to Prevent Cisplatin-Induced Hearing Loss in Children: A Nonrandomized Controlled Phase I Trial.
&lt;/a&gt;&lt;/p&gt;Clin Cancer Res (2023-Jul-05)&lt;/div&gt;'>[56]</a><a href="#ref-57" id="ref-link-57" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kranzer K, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/26347391" target="\_blank" rel="noopener noreferrer"&gt;A systematic review and meta-analysis of the efficacy and safety of N-acetylcysteine in preventing aminoglycoside-induced ototoxicity: implications for the treatment of multidrug-resistant TB.
&lt;/a&gt;&lt;/p&gt;Thorax (2015-Nov)&lt;/div&gt;'>[57]</a> NAC may also have a protective effect against noise-induced shifts in hearing thresholds (i.e., exposure to noises so loud that they temporarily or permanently raise the minimum volume at which a sound can be detected), specifically for higher sound frequencies (4–6 kHz).<a href="#ref-55" id="ref-link-55" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Chang PH, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36457967" target="\_blank" rel="noopener noreferrer"&gt;Effect of N-acetyl-cysteine in prevention of noise-induced hearing loss: a systematic review and meta-analysis of randomized controlled trials.
&lt;/a&gt;&lt;/p&gt;Arch Med Sci (2022)&lt;/div&gt;'>[55]</a> For sudden hearing loss (an unexplainable, rapid loss of hearing), combining NAC with corticosteroids may be more effective for regaining hearing than corticosteroids alone.<a href="#ref-58" id="ref-link-58" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Bai X, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36159904" target="\_blank" rel="noopener noreferrer"&gt;Effect of N-acetyl-cysteine treatment on sensorineural hearing loss: a meta-analysis.
&lt;/a&gt;&lt;/p&gt;World J Otorhinolaryngol Head Neck Surg (2022-Sep)&lt;/div&gt;'>[58]</a>

Does N-acetylcysteine affect hearing loss?

NAC reduces levels of proinflammatory cytokines and oxidative stress.<a href="#ref-1" id="ref-link-1" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Micaely Cristina Dos Santos Tenório, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34208683" target="\_blank" rel="noopener noreferrer"&gt;N-Acetylcysteine (NAC): Impacts on Human Health
&lt;/a&gt;&lt;/p&gt;Antioxidants (Basel) (2021 Jun 16)&lt;/div&gt;'>[1]</a><a href="#ref-8" id="ref-link-8" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Chad Kerksick, Darryn Willoughby. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18500954" target="\_blank" rel="noopener noreferrer"&gt;The antioxidant role of glutathione and N-acetyl-cysteine supplements and exercise-induced oxidative stress
&lt;/a&gt;&lt;/p&gt;J Int Soc Sports Nutr (2005 Dec 9)&lt;/div&gt;'>[8]</a> Because NAC increases glutathione levels in the body, which are rapidly depleted by stress, disease, or drug toxicity, it has applications in clinical settings, in addition to general health and wellness. NAC has been used for the treatment of <a href="/conditions/cystic-fibrosis/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Cystic Fibrosis&lt;/h6&gt;&lt;p&gt;&lt;em&gt;Cystic fibrosis&lt;/em&gt; (CF) is an inherited condition characterized by thick and sticky mucus that clogs the lungs and leads to breathing problems and lung infections. Cystic fibrosis can affect the lungs, pancreas, liver, intestines, sinuses, and sex organs.&lt;/p&gt;&lt;/div&gt;">cystic fibrosis</a> (due to its mucolytic properties),<a href="#ref-9" id="ref-link-9" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;M Gracey, V Burke, C M Anderson. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/5785191" target="\_blank" rel="noopener noreferrer"&gt;Treatment of abdominal pain in cystic fibrosis by oral administration of n-acetyl cysteine
&lt;/a&gt;&lt;/p&gt;Arch Dis Child (1969 Jun)&lt;/div&gt;'>[9]</a> acetaminophen (paracetamol) toxicity,<a href="#ref-10" id="ref-link-10" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kennon J Heard. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18635433" target="\_blank" rel="noopener noreferrer"&gt;Acetylcysteine for acetaminophen poisoning
&lt;/a&gt;&lt;/p&gt;N Engl J Med (2008 Jul 17)&lt;/div&gt;'>[10]</a> and <a href="/conditions/chronic-obstructive-pulmonary-disease/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Chronic Obstructive Pulmonary Disease&lt;/h6&gt;&lt;p&gt;Chronic obstructive pulmonary disease (COPD) is a chronic disease of the lungs that involves airway damage and blockage that worsens over time. The progressively worsening airway blockage causes the main symptoms of COPD: difficulty breathing, cough, and mucus production. While the most common cause of COPD is smoking, other causes can include significant exposure to air pollutants, frequent respiratory infections, and untreated asthma. Standard COPD treatments include use of specific inhalers to relax and open up the airways.&lt;/p&gt;&lt;/div&gt;">chronic obstructive pulmonary disease</a> (COPD).
In <a href="/conditions/chronic-obstructive-pulmonary-disease/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Chronic Obstructive Pulmonary Disease&lt;/h6&gt;&lt;p&gt;Chronic obstructive pulmonary disease (COPD) is a chronic disease of the lungs that involves airway damage and blockage that worsens over time. The progressively worsening airway blockage causes the main symptoms of COPD: difficulty breathing, cough, and mucus production. While the most common cause of COPD is smoking, other causes can include significant exposure to air pollutants, frequent respiratory infections, and untreated asthma. Standard COPD treatments include use of specific inhalers to relax and open up the airways.&lt;/p&gt;&lt;/div&gt;">COPD</a>, NAC may improve lung function and speed the rate of symptom improvement when used during a symptom flare up (an exacerbation).<a href="#ref-11" id="ref-link-11" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Jiang C, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34237968" target="\_blank" rel="noopener noreferrer"&gt;Systematic review and meta-analysis of the efficacy of N-acetylcysteine in the treatment of acute exacerbation of chronic obstructive pulmonary disease.
&lt;/a&gt;&lt;/p&gt;Ann Palliat Med (2021-Jun)&lt;/div&gt;'>[11]</a> Long-term use (more than 3–6 months) may improve symptoms of <a href="/conditions/chronic-bronchitis/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Chronic Bronchitis&lt;/h6&gt;&lt;p&gt;Chronic bronchitis is a type of Chronic Obstructive Pulmonary Disease (COPD) characterized by inflamed and irritated bronchial tubes, leading to mucus build-up that makes it hard for the lungs to get rid of carbon dioxide and take up oxygen efficiently.&lt;/p&gt;&lt;/div&gt;">chronic bronchitis</a> and reduce the risk of COPD exacerbations,<a href="#ref-12" id="ref-link-12" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Cazzola M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/26324807" target="\_blank" rel="noopener noreferrer"&gt;Influence of N-acetylcysteine on chronic bronchitis or COPD exacerbations: a meta-analysis.
&lt;/a&gt;&lt;/p&gt;Eur Respir Rev (2015-Sep)&lt;/div&gt;'>[12]</a><a href="#ref-13" id="ref-link-13" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Fowdar K, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28109565" target="\_blank" rel="noopener noreferrer"&gt;The effect of N-acetylcysteine on exacerbations of chronic obstructive pulmonary disease: A meta-analysis and systematic review.
&lt;/a&gt;&lt;/p&gt;Heart Lung (2017)&lt;/div&gt;'>[13]</a><a href="#ref-14" id="ref-link-14" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wei J, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31598901" target="\_blank" rel="noopener noreferrer"&gt;Effect of Orally Administered N-Acetylcysteine on Chronic Bronchitis: A Meta-analysis.
&lt;/a&gt;&lt;/p&gt;Adv Ther (2019-Dec)&lt;/div&gt;'>[14]</a> although the latter effect has not been found consistently.<a href="#ref-15" id="ref-link-15" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Huang C, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36927162" target="\_blank" rel="noopener noreferrer"&gt;The efficacy of -acetylcysteine in chronic obstructive pulmonary disease patients: a meta-analysis.
&lt;/a&gt;&lt;/p&gt;Ther Adv Respir Dis (2023)&lt;/div&gt;'>[15]</a> Additionally, NAC does not seem to prevent declining lung function when used over a long period of time.<a href="#ref-15" id="ref-link-15" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Huang C, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36927162" target="\_blank" rel="noopener noreferrer"&gt;The efficacy of -acetylcysteine in chronic obstructive pulmonary disease patients: a meta-analysis.
&lt;/a&gt;&lt;/p&gt;Ther Adv Respir Dis (2023)&lt;/div&gt;'>[15]</a>

What are N-acetylcysteine’s main benefits?

NAC has cytoprotective (cell-protecting) effects, which work through antioxidant and anti-inflammatory mechanisms. On the antioxidant side, although the NAC molecule itself has the ability to scavenge reactive oxygen species (ROS), the antioxidant effects of NAC in the body mainly occur through increasing glutathione levels and other indirect mechanisms.<a href="#ref-16" id="ref-link-16" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Anatoly Zhitkovich. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31046246" target="\_blank" rel="noopener noreferrer"&gt;N-Acetylcysteine: Antioxidant, Aldehyde Scavenger, and More
&lt;/a&gt;&lt;/p&gt;Chem Res Toxicol (2019 Jul 15)&lt;/div&gt;'>[16]</a> NAC increases glutathione levels by acting as a source of the amino acid cysteine, which is a rate-limiting building block for glutathione production.<a href="#ref-17" id="ref-link-17" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Aldini G, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29742938" target="\_blank" rel="noopener noreferrer"&gt;N-Acetylcysteine as an antioxidant and disulphide breaking agent: the reasons why.
&lt;/a&gt;&lt;/p&gt;Free Radic Res (2018-Jul)&lt;/div&gt;'>[17]</a> The anti-inflammatory effects of NAC are indirect and work through its antioxidant activity, which in turn inhibits the pro-inflammatory transcription factor NFKB-Activity<a href="#ref-18" id="ref-link-18" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;S Oka, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/10788610" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine suppresses TNF-induced NF-kappaB activation through inhibition of IkappaB kinases
&lt;/a&gt;&lt;/p&gt;FEBS Lett (2000 Apr 28)&lt;/div&gt;'>[18]</a> and reduces pro-inflammatory cytokines like <a href="/outcomes/interleukin-8/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Interleukin 8&lt;/h6&gt;&lt;p&gt;&lt;em&gt;Interleukin 8&lt;/em&gt; (IL-8) is a chemokine produced by cells (notably macrophages). It has two noteworthy functions: inducing chemotaxis (chemical-mediated cell movement, often to draw macrophages to infection sites) and stimulating phagocytosis (immune cells absorbing pathogens).&lt;/p&gt;&lt;/div&gt;">IL-8</a>, <a href="/outcomes/interleukin-6/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Interleukin 6&lt;/h6&gt;&lt;p&gt;Interleukin 6 (IL-6) is a proinflammatory cytokine that is thought to reflect a more inflammatory state in the body.&lt;/p&gt;&lt;/div&gt;">IL-6</a>, and <a href="/outcomes/tnf-alpha/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;TNF-Alpha&lt;/h6&gt;&lt;p&gt;Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine that is used as a marker of inflammation. Its reduction is thought to reflect a lesser state of inflammation in the body.&lt;/p&gt;&lt;/div&gt;">TNF-α</a>.<a href="#ref-19" id="ref-link-19" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Faghfouri AH, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32726657" target="\_blank" rel="noopener noreferrer"&gt;The effects of N-acetylcysteine on inflammatory and oxidative stress biomarkers: A systematic review and meta-analysis of controlled clinical trials.
&lt;/a&gt;&lt;/p&gt;Eur J Pharmacol (2020-Oct-05)&lt;/div&gt;'>[19]</a> 
As a mucolytic agent, NAC decreases the thickness of mucus (sputum) by reducing oxidized sulfur bonds between mucus proteins, breaking them up. In the respiratory tract, this effect allows for better mucociliary clearance (the self-cleaning mechanism within the airways) so mucus can be more effectively expelled from the lungs.<a href="#ref-15" id="ref-link-15" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Huang C, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36927162" target="\_blank" rel="noopener noreferrer"&gt;The efficacy of -acetylcysteine in chronic obstructive pulmonary disease patients: a meta-analysis.
&lt;/a&gt;&lt;/p&gt;Ther Adv Respir Dis (2023)&lt;/div&gt;'>[15]</a>
N-acetylcysteine also appears to modulate <a href="/foods/glutamate/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Glutamate&lt;/h6&gt;&lt;p&gt;Glutamate is a neurotransmitter produced by the body that plays an important role in learning, memory, and brain development. It is an amino acid found in many foods, most commonly as &lt;em&gt;monosodium glutamate&lt;/em&gt; (MSG), including tomatoes, cheese, mushrooms, seaweed, and soy.&lt;/p&gt;&lt;/div&gt;">glutamate</a> and <a href="/outcomes/dopamine/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Dopamine&lt;/h6&gt;&lt;p&gt;Dopamine is a catecholamine and neurotransmitter that can be measured in the blood, and changes in response to the diet or nutritional supplementation.&lt;/p&gt;&lt;/div&gt;">dopamine</a> neurotransmission in a way that may be beneficial for certain neuropsychiatric disorders such as <a href="/conditions/schizophrenia/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Schizophrenia&lt;/h6&gt;&lt;p&gt;Schizophrenia is a brain condition that may cause auditory and/or visual hallucinations, delusions, difficulties with emotions and cognition, and verbal communication problems. These symptoms manifest between the ages of 16 and 30.&lt;/p&gt;&lt;/div&gt;">schizophrenia</a> and <a href="/conditions/substance-use-disorder/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Substance Use Disorder&lt;/h6&gt;&lt;p&gt;Substance use disorder is an abnormal mental condition characterized by an inability to control the use of legal or illegal drugs, alcohol, or medications, leading to health issues or problems at work or home.&lt;/p&gt;&lt;/div&gt;">substance use disorder</a>. However, further research is needed to support these effects.<a href="#ref-20" id="ref-link-20" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Smaga I, Frankowska M, Filip M. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33760228" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine as a new prominent approach for treating psychiatric disorders.
&lt;/a&gt;&lt;/p&gt;Br J Pharmacol (2021-Jul)&lt;/div&gt;'>[20]</a>

How does N-acetylcysteine work?

<input id="sidebar-66290a32b43e9" type="checkbox" class="peer hidden">
<div class="sidebar ">
<label for="sidebar-66290a32b43e9">
<svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 20 20" fill="currentColor">
<path fill-rule="evenodd" d="M14.77 12.79a.75.75 0 01-1.06-.02L10 8.832 6.29 12.77a.75.75 0 11-1.08-1.04l4.25-4.5a.75.75 0 011.08 0l4.25 4.5a.75.75 0 01-.02 1.06z" clip-rule="evenodd"></path>
</svg>
</label>
Despite the long-held belief that antioxidants are protective against cancer, the relationship between antioxidants and cancer is complicated, context-dependent, and incompletely understood. 
</div>
On one hand, excessive reactive oxygen species (ROS) can damage molecules in the body, including DNA, and induce biochemical pathways that may increase the risk of cancer. Additionally, some cancers, like triple-negative breast cancer, use increased ROS signaling for their own survival and progression.<a href="#ref-47" id="ref-link-47" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kwon Y. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33498875" target="\_blank" rel="noopener noreferrer"&gt;Possible Beneficial Effects of N-Acetylcysteine for Treatment of Triple-Negative Breast Cancer.
&lt;/a&gt;&lt;/p&gt;Antioxidants (Basel) (2021-Jan-24)&lt;/div&gt;'>[47]</a> In these contexts, antioxidants such as NAC may play a beneficial role. 
On the other hand, the generation of ROS is a defense mechanism the body can use to induce cancer cell death and prevent cancer progression. While antioxidants might protect against ROS-induced damage and reduce cancer progression in some instances,<a href="#ref-48" id="ref-link-48" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Monti D, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29248134" target="\_blank" rel="noopener noreferrer"&gt;Pilot study demonstrating metabolic and anti-proliferative effects of in vivo anti-oxidant supplementation with N-Acetylcysteine in Breast Cancer.
&lt;/a&gt;&lt;/p&gt;Semin Oncol (2017-Jun)&lt;/div&gt;'>[48]</a> in other contexts they might promote cancer cell survival by reducing oxidative stress within the cell.<a href="#ref-49" id="ref-link-49" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Breau M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31578304" target="\_blank" rel="noopener noreferrer"&gt;The antioxidant N-acetylcysteine protects from lung emphysema but induces lung adenocarcinoma in mice
&lt;/a&gt;&lt;/p&gt;JCI Insight (2019 Oct 3)&lt;/div&gt;'>[49]</a> In fact, there’s evidence to suggest that one mechanism by which cancer cells promote their own survival is by increasing the body's antioxidant defense mechanisms within the cell.<a href="#ref-50" id="ref-link-50" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Hayes JD, McMahon M. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/19321346" target="\_blank" rel="noopener noreferrer"&gt;NRF2 and KEAP1 mutations: permanent activation of an adaptive response in cancer.
&lt;/a&gt;&lt;/p&gt;Trends Biochem Sci (2009-Apr)&lt;/div&gt;'>[50]</a><a href="#ref-51" id="ref-link-51" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;DeNicola GM, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21734707" target="\_blank" rel="noopener noreferrer"&gt;Oncogene-induced Nrf2 transcription promotes ROS detoxification and tumorigenesis.
&lt;/a&gt;&lt;/p&gt;Nature (2011-Jul-06)&lt;/div&gt;'>[51]</a>
There is no evidence from human clinical trials that NAC causes cancer or increases cancer progression. In breast cancer, one uncontrolled pilot study suggested that NAC might actually inhibit cancer cell proliferation.<a href="#ref-48" id="ref-link-48" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Monti D, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29248134" target="\_blank" rel="noopener noreferrer"&gt;Pilot study demonstrating metabolic and anti-proliferative effects of in vivo anti-oxidant supplementation with N-Acetylcysteine in Breast Cancer.
&lt;/a&gt;&lt;/p&gt;Semin Oncol (2017-Jun)&lt;/div&gt;'>[48]</a> However, research in mice has suggested that NAC supplementation might promote the progression of certain pre-existing cancers, including skin, liver, and lung cancer, and increase the risk of metastatic disease — in both cases, by reducing oxidative stress in the cancer cells.<a href="#ref-52" id="ref-link-52" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Le Gal K, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/26446958" target="\_blank" rel="noopener noreferrer"&gt;Antioxidants can increase melanoma metastasis in mice.
&lt;/a&gt;&lt;/p&gt;Sci Transl Med (2015-Oct-07)&lt;/div&gt;'>[52]</a><a href="#ref-53" id="ref-link-53" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Sayin VI, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/24477002" target="\_blank" rel="noopener noreferrer"&gt;Antioxidants accelerate lung cancer progression in mice
&lt;/a&gt;&lt;/p&gt;Sci Transl Med (2014 Jan 29)&lt;/div&gt;'>[53]</a><a href="#ref-54" id="ref-link-54" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Zhang VX, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34924003" target="\_blank" rel="noopener noreferrer"&gt;Antioxidant supplements promote tumor formation and growth and confer drug resistance in hepatocellular carcinoma by reducing intracellular ROS and induction of TMBIM1.
&lt;/a&gt;&lt;/p&gt;Cell Biosci (2021-Dec-19)&lt;/div&gt;'>[54]</a><a href="#ref-49" id="ref-link-49" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Breau M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31578304" target="\_blank" rel="noopener noreferrer"&gt;The antioxidant N-acetylcysteine protects from lung emphysema but induces lung adenocarcinoma in mice
&lt;/a&gt;&lt;/p&gt;JCI Insight (2019 Oct 3)&lt;/div&gt;'>[49]</a> In mice without pre-existing cancer, the effects are less clear. NAC supplementation did not induce liver cancer in otherwise healthy mice in one study,<a href="#ref-54" id="ref-link-54" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Zhang VX, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34924003" target="\_blank" rel="noopener noreferrer"&gt;Antioxidant supplements promote tumor formation and growth and confer drug resistance in hepatocellular carcinoma by reducing intracellular ROS and induction of TMBIM1.
&lt;/a&gt;&lt;/p&gt;Cell Biosci (2021-Dec-19)&lt;/div&gt;'>[54]</a> but it did increase the risk of lung cancer in healthy aged mice in another.<a href="#ref-49" id="ref-link-49" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Breau M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31578304" target="\_blank" rel="noopener noreferrer"&gt;The antioxidant N-acetylcysteine protects from lung emphysema but induces lung adenocarcinoma in mice
&lt;/a&gt;&lt;/p&gt;JCI Insight (2019 Oct 3)&lt;/div&gt;'>[49]</a> 
Clearly, the question of how NAC interacts with cancer risk or progression is incredibly nuanced, and more research is needed to understand this relationship.

Does N-acetylcysteine increase the risk or progression of cancer?

NAC is safe and effective at reasonable doses through oral supplementation. The most common side effects from oral NAC include nausea, <a href="/outcomes/vomiting/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Vomiting&lt;/h6&gt;&lt;p&gt;Vomiting is the expulsion of stomach contents from the mouth. It can be triggered from a variety of causes such as infection, dizziness, and pregnancy.&lt;/p&gt;&lt;/div&gt;">vomiting</a>, and diarrhea.<a href="#ref-1" id="ref-link-1" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Micaely Cristina Dos Santos Tenório, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34208683" target="\_blank" rel="noopener noreferrer"&gt;N-Acetylcysteine (NAC): Impacts on Human Health
&lt;/a&gt;&lt;/p&gt;Antioxidants (Basel) (2021 Jun 16)&lt;/div&gt;'>[1]</a><a href="#ref-40" id="ref-link-40" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Rhodes K, Braakhuis A. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28102488" target="\_blank" rel="noopener noreferrer"&gt;Performance and Side Effects of Supplementation with N-Acetylcysteine: A Systematic Review and Meta-Analysis.
&lt;/a&gt;&lt;/p&gt;Sports Med (2017-Aug)&lt;/div&gt;'>[40]</a> Due to the sulfur content of NAC, supplements can have an unpleasant rotten-egg odor.<a href="#ref-1" id="ref-link-1" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Micaely Cristina Dos Santos Tenório, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34208683" target="\_blank" rel="noopener noreferrer"&gt;N-Acetylcysteine (NAC): Impacts on Human Health
&lt;/a&gt;&lt;/p&gt;Antioxidants (Basel) (2021 Jun 16)&lt;/div&gt;'>[1]</a> When inhaled, NAC may cause <a href="/outcomes/cough/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Cough&lt;/h6&gt;&lt;p&gt;Coughing is a forceful reflex that is done to remove foreign objects or secretions from the airway.&lt;/p&gt;&lt;/div&gt;">cough</a> and bronchospasm (constriction of the airways).<a href="#ref-2" id="ref-link-2" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Guerini M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/35215328" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine (NAC) and Its Role in Clinical Practice Management of Cystic Fibrosis (CF): A Review.
&lt;/a&gt;&lt;/p&gt;Pharmaceuticals (Basel) (2022-Feb-11)&lt;/div&gt;'>[2]</a>
NAC toxicity mostly occurs in clinical settings, with one case of overdose occurring due to an error in the preparation of an IV solution. An excessive dose of NAC in a short time period can cause red blood cell breakdown (hemolysis), low blood platelet count (thrombocytopenia), kidney failure, and possibly death.<a href="#ref-46" id="ref-link-46" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ghafar Ali Mahmoudi, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/25767408" target="\_blank" rel="noopener noreferrer"&gt;N-acetylcysteine overdose after acetaminophen poisoning
&lt;/a&gt;&lt;/p&gt;Int Med Case Rep J (2015 Feb 27)&lt;/div&gt;'>[46]</a>

What are N-acetylcysteine’s main drawbacks?

N-Acetylcysteine

Skin, Hair, & Nails

N-Acetylcysteine (NAC): Impacts on Human Health

N-acetylcysteine (NAC) and Its Role in Clinical Practice Management of Cystic Fibrosis (CF): A Review.

N-Acetylcysteine: A Review of Clinical Usefulness (an Old Drug with New Tricks)

The reduction in vitro in viscosity of mucoprotein solutions by a new mucolytic agent, N-acetyl-L-cysteine

Targeting oxidative stress in disease: promise and limitations of antioxidant therapy.

Quantitative nutritional studies with water-soluble, chemically defined diets. III. Individual amino acids as sources of non-essential nitrogen

Long-term neurobehavioral and histological damage in brain of mice induced by L-cysteine

The antioxidant role of glutathione and N-acetyl-cysteine supplements and exercise-induced oxidative stress

Treatment of abdominal pain in cystic fibrosis by oral administration of n-acetyl cysteine

Acetylcysteine for acetaminophen poisoning

Systematic review and meta-analysis of the efficacy of N-acetylcysteine in the treatment of acute exacerbation of chronic obstructive pulmonary disease.

Influence of N-acetylcysteine on chronic bronchitis or COPD exacerbations: a meta-analysis.

The effect of N-acetylcysteine on exacerbations of chronic obstructive pulmonary disease: A meta-analysis and systematic review.

Effect of Orally Administered N-Acetylcysteine on Chronic Bronchitis: A Meta-analysis.

The efficacy of -acetylcysteine in chronic obstructive pulmonary disease patients: a meta-analysis.

N-Acetylcysteine: Antioxidant, Aldehyde Scavenger, and More

N-Acetylcysteine as an antioxidant and disulphide breaking agent: the reasons why.

N-acetylcysteine suppresses TNF-induced NF-kappaB activation through inhibition of IkappaB kinases

The effects of N-acetylcysteine on inflammatory and oxidative stress biomarkers: A systematic review and meta-analysis of controlled clinical trials.

N-acetylcysteine as a new prominent approach for treating psychiatric disorders.

Protective effect of N-acetylcysteine on experimental chronic lead nephrotoxicity in immature female rats.

The administration of N-acetylcysteine reduces oxidative stress and regulates glutathione metabolism in the blood cells of workers exposed to lead

Glutathione, glutathione-related enzymes, and oxidative stress in individuals with subacute occupational exposure to lead.

Modulation by N-acetylcysteine of lead-induced alterations in rat brain: reduced glutathione levels and morphology.

In vivo indices of oxidative stress in lead-exposed C57BL/6 mice are reduced by treatment with meso-2,3-dimercaptosuccinic acid or N-acetylcysteine.

The role of N-acetyl-cysteine (NAC) orally daily on the sperm parameters and serum hormones in idiopathic infertile men: A systematic review and meta-analysis of randomised controlled trials.

The effects of N-acetylcysteine on ovulation and sex hormones profile in women with polycystic ovary syndrome: a systematic review and meta-analysis

Comparison of the efficacy between NAC and metformin in treating PCOS patients: a meta-analysis.

The Multifaceted Therapeutic Role of N-Acetylcysteine (NAC) in Disorders Characterized by Oxidative Stress

The efficacy of nutritional supplements for the adjunctive treatment of schizophrenia in adults: A systematic review and network meta-analysis.

N-acetylcysteine for schizophrenia: A systematic review and meta-analysis.

Meta-analysis of randomised controlled trials with -acetylcysteine in the treatment of schizophrenia.

N-acetylcysteine as an adjunctive treatment for bipolar depression: A systematic review and meta-analysis of randomized controlled trials.

N-Acetylcysteine in depressive symptoms and functionality: a systematic review and meta-analysis.

Effectiveness of -acetylcysteine in autism spectrum disorders: A meta-analysis of randomized controlled trials.

N-acetylcysteine in the treatment of craving in substance use disorders: Systematic review and meta-analysis.

Free radicals and muscle fatigue: Of ROS, canaries, and the IOC.

Effect of N-acetylcysteine on diaphragm fatigue.

Reactive oxygen in skeletal muscle. I. Intracellular oxidant kinetics and fatigue in vitro.

Performance and Side Effects of Supplementation with N-Acetylcysteine: A Systematic Review and Meta-Analysis.

N-Acetylcysteine's attenuation of fatigue after repeated bouts of intermittent exercise: practical implications for tournament situations

Effect of N-acetylcysteine on cycling performance after intensified training.

N-acetylcysteine enhances muscle cysteine and glutathione availability and attenuates fatigue during prolonged exercise in endurance-trained individuals

Infusion with the antioxidant N-acetylcysteine attenuates early adaptive responses to exercise in human skeletal muscle

Acetaminophen Toxicity

N-acetylcysteine overdose after acetaminophen poisoning

Possible Beneficial Effects of N-Acetylcysteine for Treatment of Triple-Negative Breast Cancer.

Pilot study demonstrating metabolic and anti-proliferative effects of in vivo anti-oxidant supplementation with N-Acetylcysteine in Breast Cancer.

The antioxidant N-acetylcysteine protects from lung emphysema but induces lung adenocarcinoma in mice

NRF2 and KEAP1 mutations: permanent activation of an adaptive response in cancer.

Oncogene-induced Nrf2 transcription promotes ROS detoxification and tumorigenesis.

Antioxidants can increase melanoma metastasis in mice.

Antioxidants accelerate lung cancer progression in mice

Antioxidant supplements promote tumor formation and growth and confer drug resistance in hepatocellular carcinoma by reducing intracellular ROS and induction of TMBIM1.

Effect of N-acetyl-cysteine in prevention of noise-induced hearing loss: a systematic review and meta-analysis of randomized controlled trials.

Intravenous N-Acetylcysteine to Prevent Cisplatin-Induced Hearing Loss in Children: A Nonrandomized Controlled Phase I Trial.

A systematic review and meta-analysis of the efficacy and safety of N-acetylcysteine in preventing aminoglycoside-induced ototoxicity: implications for the treatment of multidrug-resistant TB.

Effect of N-acetyl-cysteine treatment on sensorineural hearing loss: a meta-analysis.

Nick Milazzo

Dmitri Barvinok

Bill Willis

Natalka Roshak

Katie Jantz

Daryl Nault

Allergies & Immunity

Chronic Obstructive Pulmonary Disease

COPD Symptoms

Bronchitis Symptoms

Forced Expiratory Volume

Glutathione (GSH)

Chronic Bronchitis

Forced Vital Capacity

Lung Function

Neutrophil Activity

Autism Spectrum Disorder

Autism Symptoms

Irritability

Hearing Loss

Polycystic Ovary Syndrome

Follicle-Stimulating Hormone

Ovulation

Rate Of Pregnancy

Testosterone

Endometrial Thickness

Estrogen

Luteinizing Hormone

Progesterone

Sex Hormone Binding Globulin

Healthy Aging

Immune Health

Diabetes & Blood Sugar

Cardiovascular Health

Liver Health

Metabolic Health

Anti-Oxidant Enzyme Profile

Anaerobic Capacity

Mineral Bioaccumulation

Surgical Recovery

Liver Enzymes

All-Cause Mortality

Heart Arrythmias

Heart Attack Risk

Kidney Function

Length of hospitalization

Skin, Hair & Nails

Acne

Acne Symptoms

Mood & Depression

Depression

Depression Symptoms

Anxiety Symptoms

Infertility

Fat Loss

Obesity

Aerobic Exercise Performance

Cycling Performance

Sprint Performance Metrics

Bipolar Disorder

Acute Bronchitis

Cannabis Use Disorder

Marijuana Addiction

Cardiovascular Disease

Urinary NOx

General Cardiovascular Health

Chronic Pain

Joint Pain (General)

Neuropathic Pain Symptoms

Quality of Life

Cocaine Abuse

Cocaine Addiction Symptoms

Cystic Fibrosis

General Liver Health

H. Pylori Infection

Helicobacter Pylori Infection Signs

Kidney Health

Obsessive-Compulsive Disorder

OCD Symptoms

Overweight

Schizophrenia

Schizophrenia symptoms

Working Memory

Processing Speed

Soccer Performance

Power Output

Tobacco Use Disorder

Tobacco Addiction Symptoms

Trichotillomania

Trichotillomania Symptoms

Subjective Well-Being

Substance Use Disorder

Idiopathic Pulmonary Fibrosis

Safety and tolerability of N-acetylcysteine in cocaine-dependent individuals

N-Acetylcysteine Attenuates Fatigue Following Repeated-Bouts of Intermittent Exercise: Practical Implications for Tournament Situations

N-acetylcysteine, a glutamate modulator, in the treatment of trichotillomania: a double-blind, placebo-controlled study

New developments in the treatment of COPD: comparing the effects of inhaled corticosteroids and N-acetylcysteine

Induced sputum of patients with chronic obstructive pulmonary disease (COPD) contains adhesion-promoting, therapy-sensitive factors

N-acetylcysteine add-on treatment in refractory obsessive-compulsive disorder: a randomized, double-blind, placebo-controlled trial

Randomised, controlled trial of N-acetylcysteine for treatment of acute exacerbations of chronic obstructive pulmonary disease

Effects of N-acetylcysteine on outcomes in chronic obstructive pulmonary disease (Bronchitis Randomized on NAC Cost-Utility Study, BRONCUS): a randomised placebo-controlled trial

Long-term oral n-acetylcysteine reduces exhaled hydrogen peroxide in stable COPD

A randomized controlled pilot trial of oral N-acetylcysteine in children with autism

A randomized double blind placebo controlled clinical trial of N-Acetylcysteine added to risperidone for treating autistic disorders

N-Acetylcysteine (NAC) inhibits renal nitrite and nitrate reabsorption in healthy subjects and in patients undergoing cardiac surgery: risk of nitric oxide (NO) bioavailability loss by NAC?

The role of cystine-glutamate exchange in nicotine dependence in rats and humans

N-acetylcysteine (NAC) in young marijuana users: an open-label pilot study

Effects of Oral Antioxidants on Lesion Counts Associated with Oxidative Stress and Inflammation in Patients with Papulopustular Acne

Antioxidant supplementation for lung disease in cystic fibrosis.

Meta-analytic Techniques to Assess the Association Between N-acetylcysteine and Acute Kidney Injury After Contrast Administration: A Systematic Review and Meta-analysis.

The efficacy of adjuvant N acetyl cysteine for the eradication of H pylori infections: A systematic review and meta-analysis of randomized clinical trials.

N-acetylcysteine in the Donor, Recipient, or Both Donor and Recipient in Liver Transplantation: A Systematic Review With Meta-analysis and Trial Sequential Analysis.

N-acetylcysteine use among patients undergoing cardiac surgery: A systematic review and meta-analysis of randomized trials.

-acetyl-cysteine as adjuvant therapy in female infertility: a systematic review and meta-analysis.

Efficacy and Safety of N-Acetylcysteine for the Management of Chronic Pain in Adults: A Systematic Review and Meta-Analysis.

Pirfenidone, nintedanib and N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis: A systematic review and meta-analysis.

N-acetylcysteine (NAC) is an acetylated form of the amino acid L-cysteine. It has antioxidant and anti-inflammatory properties and is a mucolytic agent, meaning that it helps break down mucus in the respiratory tract.[reference|url=https://pubmed.ncbi.nlm.nih.gov/34221501|title=N-Acetylcysteine: A Review of Clinical Usefulness (an Old Drug with New Tricks)|published=2021 Jun 9|authors=Gerry K Schwalfenberg|journal=J Nutr Metab|] NAC is converted to L-cysteine after ingestion, which, in turn, is converted into glutathione (GSH), a powerful antioxidant. 
L-cysteine can’t be supplemented on its own because free L-cysteine is highly unstable, becoming readily oxidized in solution which can encourage the formation of insoluble precipitates.[reference|url=https://pubmed.ncbi.nlm.nih.gov/13977050|title=The reduction in vitro in viscosity of mucoprotein solutions by a new mucolytic agent, N-acetyl-L-cysteine|published=1963 Mar 30|authors=A L SHEFFNER|journal=Ann N Y Acad Sci|] Similarly, glutathione is rapidly broken down in the gastrointestinal tract and blood, limiting its availability in the body when supplemented directly.[reference|url=https://pubmed.ncbi.nlm.nih.gov/34194012|title=Targeting oxidative stress in disease: promise and limitations of antioxidant therapy.|published=2021-Sep|authors=Forman HJ, Zhang H|journal=Nat Rev Drug Discov|] In contrast, NAC is more stable and has a much lower toxicity than free L-cysteine,[reference|url=https://pubmed.ncbi.nlm.nih.gov/13479126|title=Quantitative nutritional studies with water-soluble, chemically defined diets. III. Individual amino acids as sources of non-essential nitrogen|published=1957 Dec|authors=S M BIRNBAUM, M WINITZ, J P GREENSTEIN|journal=Arch Biochem Biophys|][reference|url=https://pubmed.ncbi.nlm.nih.gov/12957221|title=Long-term neurobehavioral and histological damage in brain of mice induced by L-cysteine|published=2003 Jul|authors=Vered Gazit, Ron Ben-Abraham, Chaim G Pick, Izhar Ben-Shlomo, Yeshayahu Katz|journal=Pharmacol Biochem Behav|] making it safer and more effective for increasing cysteine and glutathione levels in the body.

N-Acetylcysteine

Don't miss out on the latest research