Kava

    Written by:
    Daryl Nault

    Fact-checked

    by:

    Nick Milazzo
    Last Updated: March 6, 2024

    Kava (Piper methysticum) is a plant that has had many traditional uses throughout history, especially among South Pacific Islanders. It is best known for anxiety reduction but comes with some serious safety concerns when used in excess.

    Kava is most often used for Energy & Fatigue. The Examine Database covers Anxiety, Generalized Anxiety Disorder, and 5 other conditions and goals.

    110 references on this page
    1,844 participants in 10 trials and 3 meta-analyses

    What is kava?

    Kava (Piper methysticum) is a member of the pepper family (Piperaceae). As a traditional herbal therapy, kava goes by many names. Traditionally, kava has been (and still is) consumed as an infusion of the macerated root/rhizome, which is soaked in a liquid such as water, coconut milk, or alcohol. Traditional Hawaiian uses of kava have also included plant parts beyond the root, extending to the bark, plant ash, buds, young leaves, and even the whole plant.[28]

    Kava is also used recreationally, and although the plant is native to Oceania, it can now be found nearly worldwide. However, due to the potential for liver injury, kava may be restricted in some countries.[20] Whether used recreationally or traditionally, kava is known to alleviate anxiety, sleep disturbances, and provide a mildly euphoric sensation.[20][21][29] Individual responses to kava may vary, and at least one clinical trial has suggested that there may be a genetic component to this variability.[30]

    What are the known traditional, historical, and cultural uses of kava?What forms does kava typically come in?

    What are kava’s main benefits?

    One reported benefit of kava, especially in comparison to many other anxiolytics, is its ability to relieve symptoms without compromising mental clarity. For this reason, claims that kava is a hypnotic or psychedelic may be exaggerations.[20]

    Kava is best known for anxiety reduction but may not affect all types of anxiety. The clinical evidence of its effectiveness for generalized anxiety disorder or anxiety that is comorbid with depression is mixed.[25][9][31][32][18][10] However, clinical evidence for kava’s effectiveness for short-term anxiety and for anxiety resulting from specific circumstances or situations is more consistently positive.[33][34][35][36][14][19][37][38]

    Several clinical studies have shown that kava may be able to reduce anxiety without the deleterious effects on cognition seen with other anxiolytics. It has also been suggested that kava could improve cognitive processing, although such cognitive improvements may simply be byproducts of anxiety reduction; more research is needed to clarify this point.[30][12][16][39][40]

    Kava use has also been connected with a near-immediate mood boost[12] and may treat sleep disturbances associated with anxiety.[11] However, kava is still not widely recommended or accepted as a treatment for insomnia, especially in place of therapies with stronger evidence of safety and efficacy.[41][42][43]

    Does kava help with mental health?What other benefits might kava have?

    What are kava’s main drawbacks?

    When taken consistently for longer than a month or in higher doses (1,000 mg/day or more), kava use is more likely to result in liver damage or dysfunction, liver enzyme impairment, and, in rare cases, death.[1][29][3][44][45][46] Some experts suggest that reports of liver damage with kava use may be unfairly blaming kava, when other factors were actually at play.[29][47][44] While no controlled trials using standardized formulations have reported liver injury, not all trials assess the participants for this adverse event.[14][48] Until kava’s potential for liver damage has been fully and accurately assessed, caution is advised. See our additional FAQ below,What long-term side effects are associated with kava?, to learn more details.

    Kava’s reported side effects include headaches, sleepiness, sedation, diarrhea, and skin rashes.[49][50][51][52][20] Observational research suggests an association between kava use in pregnancy and low infant birth weight, but kava has not been established as a direct cause of the outcome.[53] Kava powder taken in very high doses (more than 100 times the dose at which liver damage has been observed) may result in a state similar to alcohol intoxication.[29][24] Long-term kava use has also been associated with negative outcomes similar to those seen in alcoholism, such as increased liver enzymes, which could suggest liver injury, and reductions in the number of lymphocytes, which could negatively impact immune response.[23][24] The latter finding is particularly interesting, because reducing anxiety and/or stress has generally been associated with improvements in immune response. Combining kava with alcohol may also magnify the effects of both substances.[26][27]

    Does kava interact with any other substances?What short-term side effects are associated with kava?What long-term side effects are associated with kava?

    How does kava work?

    The kavalactones contained in kava root are a group of bioactive compounds responsible for its effects. The most notable kavalactones include kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin.[20][54][55] In animal studies, kavalactones have demonstrated the ability to cross the blood-brain barrier, which helps explain why kava has a psycho-emotional effect.[56] When taken orally at a dosage of 120 mg of kava per kg of body weight, effects have been seen within an hour as kavalactones begin to accumulate in the brain.[57][12]

    Kavalactones may impart their psycho-emotional effects via glutaminergic, GABAergic, dopaminergic, and/or serotonergic signaling. It has so far proved difficult to establish the effects of individual kavalactones for two reasons: first, the effects of any individual kavalactone may be dose-dependent in ways we don’t understand; and second, when kavalactones are combined, they may not only have interactions, but those interactions could potentially vary depending on the ratio of the kavalactones in combination. In addition, both of these factors may affect humans and animal models differently, making it even harder to tease out these complex relationships. For example, case studies have reported seeing clinical signs of dopamine receptor blockage as a result of kava consumption,[58] but animal studies have not always supported the existence of an antidopaminergic effect.[59][60][61] Similarly, while a rodent trial found that mixed kavalactones did not affect serotonin levels, isolated dihydromethysticin increased serotonin in rats, while isolated desmethoxyyagonin produced reductions in it.[59]

    While kavain damaged cultured rat neurons in vitro at concentrations of 300 µM or greater (i.e., greater than or equal to 300 micromoles of kavain per liter),[62] the kavalactones dihydromethysticin and methysticin may hold neuroprotective effects.[63] Animal and nonclinical studies suggest that dihydromethysticin and methysticin may also impart sedative effects through indirect GABAergic signaling.[59][56][64][65][66]

    As with any plant or herbal preparation, factors such as plant part, growth conditions, and extraction methods may affect kavalactone content. Kava preparations with a standardized kavalactone concentration are more likely to produce consistent effects.

    What are other names for Kava?

    Note that Kava is also known as:

    • Piper methysticum
    • Kava Pepper
    • Ava Pepper
    • Kava Kava
    • Intoxicating Pepper
    • Awa
    • rauschpfeffer
    • sakau
    • tonga
    • wurzelstock
    • Tangona

    Dosage information

    No optimal dosages or durations for kava consumption have been determined at this point.[8] Kava dosing, especially in standardized formulations, may be done with reference to the kavalactone (specifically, kavapyrone; all known kavalactones are pyrones) content. Clinical trials have used dosages ranging from 100 to 400 mg/day of kava, and from 60 to 630 mg of kavalactones, per day.[9][10][11][12][13]

    As with any plant or herbal preparation, factors such as plant part, growth conditions, and extraction methods may affect the bioactivity of kava supplements. Ideally, supplements will identify a standardized kavalactone content to improve consistency of results.[14][15][16][17][18][19] There appears to be some potential for substance abuse of kava, but when it is taken at the more commonly seen dosages, this is rare.[20]

    Some of kava’s active ingredients may be secreted in breast milk. Since the effects of kava in infants are still not known, use of kava while pregnant or breastfeeding is not advised.[21]

    Kava may also interact with other substances like alcohol and St. John’s wort, possibly amplifying both positive and negative effects.[22][23][24][25] Reports of these interactions are varied, though, and may depend on circumstances such as dose, timing, format, and external factors.[26][27] Therefore, combination therapies that include kava should be considered with caution.

    Examine Database: Kava

    Frequently asked questions

    What is kava?

    Kava (Piper methysticum) is a member of the pepper family (Piperaceae). As a traditional herbal therapy, kava goes by many names. Traditionally, kava has been (and still is) consumed as an infusion of the macerated root/rhizome, which is soaked in a liquid such as water, coconut milk, or alcohol. Traditional Hawaiian uses of kava have also included plant parts beyond the root, extending to the bark, plant ash, buds, young leaves, and even the whole plant.[28]

    Kava is also used recreationally, and although the plant is native to Oceania, it can now be found nearly worldwide. However, due to the potential for liver injury, kava may be restricted in some countries.[20] Whether used recreationally or traditionally, kava is known to alleviate anxiety, sleep disturbances, and provide a mildly euphoric sensation.[20][21][29] Individual responses to kava may vary, and at least one clinical trial has suggested that there may be a genetic component to this variability.[30]

    What are the known traditional, historical, and cultural uses of kava?

    Kava, also known as kava kava, is a plant that originated in the warm South Pacific islands of Hawaiʻi, Tonga, Micronesia, Fiji, Vanuatu, and the Samoas. Kava use in Polynesia and Micronesia takes place within a traditional or cultural context, leading to different patterns of use than are seen elsewhere.[67][68] In Polynesian and Micronesian cultures, kava is often consumed as a drink as part of group sessions. These kava sessions, which take place in a community setting and involve conversation, may last for several hours.[69][49] Although kava may be consumed differently in cultures where it is not a native plant, the reasons for consumption (e.g., anxiety, relaxation, socialization) are generally similar.[29]

    Kava root has been traditionally used by the Indigenous people of Hawaiʻi. Hawaiian cultural uses for kava include a range of conditions, from easing stomach upset in children to gynecological aids, in addition to its better-known use as a relaxant.[28]

    What forms does kava typically come in?

    Traditionally, kava root is macerated, then steeped in a liquid (e.g., water, coconut milk, alcohol) and strained before being drunk.[70] Some reported traditional medicinal uses also incorporate plant parts other than the root.[28]

    Less-traditional kava preparations include (but aren’t limited to) tinctures, teas, capsules, and dried powders. When researchers tested different preparations, they found a wide variety of kavalactone content, sometimes inconsistent with the labeling.[71] Kava extracts have been used in cosmetics, but there is still insufficient evidence regarding both kava’s toxicity and efficacy when applied topically.[70]

    Standardized preparations of kava also exist and can be found throughout the scientific literature. The standardized preparations cited most frequently in clinical trials include kava root extractions (ethanol-in-water or acetone) standardized to 30–70% kavalactones.[13][36]

    What are kava’s main benefits?

    One reported benefit of kava, especially in comparison to many other anxiolytics, is its ability to relieve symptoms without compromising mental clarity. For this reason, claims that kava is a hypnotic or psychedelic may be exaggerations.[20]

    Kava is best known for anxiety reduction but may not affect all types of anxiety. The clinical evidence of its effectiveness for generalized anxiety disorder or anxiety that is comorbid with depression is mixed.[25][9][31][32][18][10] However, clinical evidence for kava’s effectiveness for short-term anxiety and for anxiety resulting from specific circumstances or situations is more consistently positive.[33][34][35][36][14][19][37][38]

    Several clinical studies have shown that kava may be able to reduce anxiety without the deleterious effects on cognition seen with other anxiolytics. It has also been suggested that kava could improve cognitive processing, although such cognitive improvements may simply be byproducts of anxiety reduction; more research is needed to clarify this point.[30][12][16][39][40]

    Kava use has also been connected with a near-immediate mood boost[12] and may treat sleep disturbances associated with anxiety.[11] However, kava is still not widely recommended or accepted as a treatment for insomnia, especially in place of therapies with stronger evidence of safety and efficacy.[41][42][43]

    Does kava help with mental health?

    Anxiety reduction is the best-known use case for kava. Clinical studies indicate that standardized kava preparations (210–300 mg, containing either 30 or 70% kavalactones depending on standardization used) could be a safe and effective alternative to benzodiazepines for the treatment of short-term anxiety.[36][14][19][37][31][38][32][18][10] Clinical evidence still appears to be mixed, however, regarding the effectiveness of kava for generalized anxiety disorder (GAD). Trials of standardized preparations (300–400 mg/day) have had the strongest results, possibly through effects on vasovagal response.[72][15][13] Similar studies using different doses and/or preparations do not support kava use for GAD.[73][17][74]

    Kava has also been studied for other anxiety disorders. People experiencing postmenopausal anxiety saw reductions in symptoms when hormone replacement therapy was combined with lower doses (100 mg/day) of kava extract for periods of three to six months.[34][35] Clinical studies including both menopausal and perimenopausal women similarly saw improvements in menopause-related anxiety with kava extract (100–300 mg/day over 8 to 12 weeks) compared to a control.[33][9]

    Finally, there is some indication that kava can boost mood in individuals without apparent health conditions. One trial noted that a single 300 mg dose of kava extract (containing 90 mg kavalactones) resulted in mood boosts that occurred within about an hour.[12]

    What other benefits might kava have?

    The effects of kava on cognition have also been a point of interest since the current standard therapy medications for anxiety can reduce cognitive functioning, while kava may not.[30][12][16][39][40]

    Two randomized clinical trials which compared an “acute dose” of kava (containing 180 mg of kavalactones) to benzodiazepines found that, while the lower kava dose couldn’t reduce anxiety as well as benzodiazepines, anxiety did not increase for kava users either. Kava users were also able to maintain alertness in cognitive tasks such as driving, which was not the case for participants taking benzodiazepines.[16][30]

    Similar clinical studies using kava doses at 300 mg or more suggest that it doesn’t impair the cognitive skills required for operating a motor vehicle and could even improve cognitive tasks requiring accuracy or quicker response time.[12][69]

    What are kava’s main drawbacks?

    When taken consistently for longer than a month or in higher doses (1,000 mg/day or more), kava use is more likely to result in liver damage or dysfunction, liver enzyme impairment, and, in rare cases, death.[1][29][3][44][45][46] Some experts suggest that reports of liver damage with kava use may be unfairly blaming kava, when other factors were actually at play.[29][47][44] While no controlled trials using standardized formulations have reported liver injury, not all trials assess the participants for this adverse event.[14][48] Until kava’s potential for liver damage has been fully and accurately assessed, caution is advised. See our additional FAQ below,What long-term side effects are associated with kava?, to learn more details.

    Kava’s reported side effects include headaches, sleepiness, sedation, diarrhea, and skin rashes.[49][50][51][52][20] Observational research suggests an association between kava use in pregnancy and low infant birth weight, but kava has not been established as a direct cause of the outcome.[53] Kava powder taken in very high doses (more than 100 times the dose at which liver damage has been observed) may result in a state similar to alcohol intoxication.[29][24] Long-term kava use has also been associated with negative outcomes similar to those seen in alcoholism, such as increased liver enzymes, which could suggest liver injury, and reductions in the number of lymphocytes, which could negatively impact immune response.[23][24] The latter finding is particularly interesting, because reducing anxiety and/or stress has generally been associated with improvements in immune response. Combining kava with alcohol may also magnify the effects of both substances.[26][27]

    Does kava interact with any other substances?

    When kava is combined with alcohol, reports vary on whether this amplifies the short-term negative effects of alcohol consumption.[26][27] Mixing kava and alcohol may increase both the sedative effects and the liver damage caused by either alone.[22]

    One clinical study, in which kava was combined with St. John's Wort (990 μg of hypericin and 50 mg of kavalactones per capsule, taken 3 times a day for 4 weeks), found a reduction of depression-related symptoms of anxiety. There were also some reports of heightened emotional sensitivity and disturbed sleep in individuals taking the combination, but no conclusions could be made regarding the combination’s synergistic effects.[25]

    What short-term side effects are associated with kava?

    Commonly reported side effects of kava use include headaches, sleepiness, sedation, diarrhea, and distinctive skin rashes called “kava dermopathy”.[49][50][51][52][20] Kava use may increase the risk of low birth weight when consumed during pregnancy; however, this was reported in an observational study, so other risk factors leading to kava use (stress, for example) may have played a role.[53] Upset stomach is a rarely-mentioned side effect but is sometimes reported to occur more with kava than in placebo groups.[19][75]

    The use of kava powder in very high doses (205 grams) has resulted in clinical effects similar to alcohol intoxication.[29][24] Occasionally, this may be called “kava intoxication”, since it’s been described as a somewhat-less-aggressive and happier state of “drunkenness”.[76] Consuming the herb in much larger quantities (3.6 to 13L of traditionally prepared kava beverage, estimated to be the equivalent of over 8,000 mg of kavalactones per day) as part of traditional kava sessions may put users at risk for short-term impairments in motor vehicle operation and cognitive response as well.[69][23][24][77]

    What long-term side effects are associated with kava?

    There are clinical reports of herb-induced liver injury with kava use, especially when taken consistently for longer than a month.[1] Prolonged kava use has been associated with lower body weight and depressed markers of immune function similar to those seen in alcoholics.[23][24] Reports of multiple adverse events, liver dysfunction (e.g., hepatotoxicity, hepatitis, hepatic failure), and, in some instances, death have also been reported, but the dose and duration of kava aren’t always consistent or clearly stated in these reports.[29][3][44][45][46]

    These accounts, however, may be mistaken in the assumption that kava alone is to blame. While some adverse event reports identify the use of individual kavalactones (rather than a whole root extract), other reports note that kava was taken in addition to another substance with the potential for hepatotoxicity.[29][47][44]

    Additionally, no controlled trials using a standardized kava intervention (i.e, 200–300 mg of standardized extracts, taken for less than 2 months) have reported liver toxicity with the use of moderate dosing. However, not all studies measure liver enzymes or function either.[14][48] Regardless of whether kava alone or in combination with other factors is to blame for adverse events, caution is advised until clearer evidence is established.

    Higher doses of kava (greater than 1,000 mg/day of root extract over 4 weeks) are associated with an increased risk of impaired cytochrome P450 (CYP450) function.[5] Inhibition of CYP450 is possibly due to kava containing methysticin, as demonstrated by in vitro studies.[78] In vitro studies have also identified that some kavalactones (desmethoxyyangonin, methysticin, and dihydromethysticin) could inhibit liver enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP4A9/11.[79][80][81] However, the kavalactone kavain is not yet known to inhibit liver enzymes.[79]

    How does kava work?

    The kavalactones contained in kava root are a group of bioactive compounds responsible for its effects. The most notable kavalactones include kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin.[20][54][55] In animal studies, kavalactones have demonstrated the ability to cross the blood-brain barrier, which helps explain why kava has a psycho-emotional effect.[56] When taken orally at a dosage of 120 mg of kava per kg of body weight, effects have been seen within an hour as kavalactones begin to accumulate in the brain.[57][12]

    Kavalactones may impart their psycho-emotional effects via glutaminergic, GABAergic, dopaminergic, and/or serotonergic signaling. It has so far proved difficult to establish the effects of individual kavalactones for two reasons: first, the effects of any individual kavalactone may be dose-dependent in ways we don’t understand; and second, when kavalactones are combined, they may not only have interactions, but those interactions could potentially vary depending on the ratio of the kavalactones in combination. In addition, both of these factors may affect humans and animal models differently, making it even harder to tease out these complex relationships. For example, case studies have reported seeing clinical signs of dopamine receptor blockage as a result of kava consumption,[58] but animal studies have not always supported the existence of an antidopaminergic effect.[59][60][61] Similarly, while a rodent trial found that mixed kavalactones did not affect serotonin levels, isolated dihydromethysticin increased serotonin in rats, while isolated desmethoxyyagonin produced reductions in it.[59]

    While kavain damaged cultured rat neurons in vitro at concentrations of 300 µM or greater (i.e., greater than or equal to 300 micromoles of kavain per liter),[62] the kavalactones dihydromethysticin and methysticin may hold neuroprotective effects.[63] Animal and nonclinical studies suggest that dihydromethysticin and methysticin may also impart sedative effects through indirect GABAergic signaling.[59][56][64][65][66]

    As with any plant or herbal preparation, factors such as plant part, growth conditions, and extraction methods may affect kavalactone content. Kava preparations with a standardized kavalactone concentration are more likely to produce consistent effects.

    Update History

    Examine Database References

    1. Subjective Well-Being - Volz HP, Kieser MKava-kava extract WS 1490 versus placebo in anxiety disorders--a randomized placebo-controlled 25-week outpatient trialPharmacopsychiatry.(1997 Jan)
    2. Subjective Well-Being - Gastpar M, Klimm HDTreatment of anxiety, tension and restlessness states with Kava special extract WS 1490 in general practice: a randomized placebo-controlled double-blind multicenter trialPhytomedicine.(2003 Nov)
    3. Subjective Well-Being - Malsch U, Kieser MEfficacy of kava-kava in the treatment of non-psychotic anxiety, following pretreatment with benzodiazepinesPsychopharmacology (Berl).(2001 Sep)
    4. Anxiety Symptoms - Pittler MH, Ernst EKava extract for treating anxietyCochrane Database Syst Rev.(2003)
    5. Anxiety Symptoms - Lehrl SClinical efficacy of kava extract WS 1490 in sleep disturbances associated with anxiety disorders. Results of a multicenter, randomized, placebo-controlled, double-blind clinical trialJ Affect Disord.(2004 Feb)
    6. Anxiety Symptoms - Geier FP, Konstantinowicz TKava treatment in patients with anxietyPhytother Res.(2004 Apr)
    7. Anxiety Symptoms - Zhang W, Yan Y, Wu Y, Yang H, Zhu P, Yan F, Zhao R, Tian P, Wang T, Fan Q, Su ZMedicinal herbs for the treatment of anxiety: A systematic review and network meta-analysis.Pharmacol Res.(2022-May)
    8. Anxiety Symptoms - Pittler MH, Ernst EEfficacy of kava extract for treating anxiety: systematic review and meta-analysis.J Clin Psychopharmacol.(2000-Feb)
    9. Anxiety Symptoms - Connor KM, Davidson JRA placebo-controlled study of Kava kava in generalized anxiety disorderInt Clin Psychopharmacol.(2002 Jul)
    10. Anxiety Symptoms - Sarris J, Kavanagh DJ, Byrne G, Bone KM, Adams J, Deed GThe Kava Anxiety Depression Spectrum Study (KADSS): a randomized, placebo-controlled crossover trial using an aqueous extract of Piper methysticumPsychopharmacology (Berl).(2009 Aug)
    11. Stress Signs and Symptoms - D WheatleyKava and valerian in the treatment of stress-induced insomniaPhytother Res.(2001 Sep)
    12. Stress Signs and Symptoms - Cropley M, Cave Z, Ellis J, Middleton RWEffect of kava and valerian on human physiological and psychological responses to mental stress assessed under laboratory conditionsPhytother Res.(2002 Feb)
    13. Reaction Time - Thompson R, Ruch W, Hasenöhrl RUEnhanced cognitive performance and cheerful mood by standardized extracts of Piper methysticum (Kava-kava)Hum Psychopharmacol.(2004 Jun)