Common Cold

    Researchedby:
    Nick Milazzo

    Fact-checked

    by:

    Mike Murray, James Gaylor
    Last Updated: October 13, 2024

    “The common cold” is a catch-all term for certain mild viral upper respiratory tract infections. There are no cures for the common cold; treatments are focused primarily on improving symptoms. Fortunately, colds typically resolve on their own in 2–14 days.

    examine-databaseExamine Database

    Common Cold falls under the Immunity & Infectious Disease category.

    44 references on this page
    28,554 participants in 75 trials and 5 meta-analyses

    What is the common cold?

    Although “the common cold” is typically treated like a single condition, it’s actually a generic term for mild upper respiratory tract infections caused by viruses (such as rhinovirus, respiratory syncytial virus, human metapneumovirus, and non-COVID coronavirus, to name a few). It’s one of the most common illnesses in the world — adults will get 2–3 colds each year, on average, and children can get many more.[1] [2]

    What are the main signs and symptoms of the common cold?

    One of the key differences between colds and the flu is symptom severity. Colds tend to be mild; the flu is often more severe, and the latter may not involve upper respiratory symptoms at all.[3]

    • Fever (common in children; less common in adults)
    • Runny or stuffy nose
    • Green or yellow nasal discharge
    • Sore throat
    • Coughing/sneezing
    • Fatigue
    • Muscle aches
    • Headache

    How is the common cold diagnosed?

    Colds are frequently self-diagnosed. In a clinical setting, they are primarily diagnosed based on a clinician’s impression of their patient’s symptoms. Typically, a “cold” is distinguished from the flu based on how quickly the symptoms come on and how severe they are. Historically, it’s been rare for clinicians to perform diagnostic tests, but post-COVID-19, it’s becoming more common.

    What are some of the main medical treatments for the common cold?

    There are no cures for the common cold; treatments are focused on managing symptoms until the cold ultimately resolves on its own. For this purpose, people may use:

    • Anti-inflammatory medications such as non-steroidal anti-inflammatory medications (NSAIDs) or acetaminophen.[4][5]
    • Decongestants such as ephedrine and pseudoephedrine.[6]

    Have any supplements been studied for the common cold?

    Again, no supplements can cure the common cold. However, zinc seems to quite reliably reduce symptom duration. Echinacea, Pelargonium sidoides, and garlic may also be helpful for reducing symptom duration, but there’s not enough research to know definitively.

    How do I know if micronutrients might be beneficial for me?

    Which supplements can help against colds and the flu?

    How could diet affect the common cold?

    Diet is mainly related to the common cold through immunity. Diets that are sufficient in energy, micronutrients, and macronutrients are important for maintaining a robust immune system, which will help reduce the risk and severity of common cold infections.[7] Flavonoids (plant compounds that have antioxidant and immunomodulatory properties; found in especially high quantities in tea, chocolate, capers, and oregano)[8] may be a noteworthy nutrient for this purpose.[9]

    Are there any other treatments for the common cold?

    Saline nasal and sinus irrigation (using devices like a neti pot or a nebulizer) may improve cold symptoms. However, it’s very important to only use water that has been filtered, sterilized, or otherwise treated for such uses — serious infections can occur otherwise.[10]

    Some trials report that meditation and exercise may reduce the risk and severity of the common cold.[11][12]

    What causes the common cold?

    The common cold is caused by a large number of viruses. Over 200 viruses have been identified as causing colds, many of which are classified as rhinoviruses. These viruses are constantly present in the environment, and infection can occur from physical contact with infected people or surfaces, breathing in small-particle aerosols containing virus in the air, or being directly hit by large-particle aerosols from a person coughing or sneezing.[13][1] Infections are most common in the winter and spring and during rainy seasons in tropical areas.[13]

    Examine Database: Common Cold

    Research FeedRead all studies

    Frequently asked questions

    What is the common cold?

    Although “the common cold” is typically treated like a single condition, it’s actually a generic term for mild upper respiratory tract infections caused by viruses (such as rhinovirus, respiratory syncytial virus, human metapneumovirus, and non-COVID coronavirus, to name a few). It’s one of the most common illnesses in the world — adults will get 2–3 colds each year, on average, and children can get many more.[1] [2]

    What are the main signs and symptoms of the common cold?

    One of the key differences between colds and the flu is symptom severity. Colds tend to be mild; the flu is often more severe, and the latter may not involve upper respiratory symptoms at all.[3]

    • Fever (common in children; less common in adults)
    • Runny or stuffy nose
    • Green or yellow nasal discharge
    • Sore throat
    • Coughing/sneezing
    • Fatigue
    • Muscle aches
    • Headache
    How is the common cold diagnosed?

    Colds are frequently self-diagnosed. In a clinical setting, they are primarily diagnosed based on a clinician’s impression of their patient’s symptoms. Typically, a “cold” is distinguished from the flu based on how quickly the symptoms come on and how severe they are. Historically, it’s been rare for clinicians to perform diagnostic tests, but post-COVID-19, it’s becoming more common.

    What are some of the main medical treatments for the common cold?

    There are no cures for the common cold; treatments are focused on managing symptoms until the cold ultimately resolves on its own. For this purpose, people may use:

    • Anti-inflammatory medications such as non-steroidal anti-inflammatory medications (NSAIDs) or acetaminophen.[4][5]
    • Decongestants such as ephedrine and pseudoephedrine.[6]
    Have any supplements been studied for the common cold?

    Again, no supplements can cure the common cold. However, zinc seems to quite reliably reduce symptom duration. Echinacea, Pelargonium sidoides, and garlic may also be helpful for reducing symptom duration, but there’s not enough research to know definitively.

    How do I know if micronutrients might be beneficial for me?

    If you are healthy and eat a well-balanced, diverse diet, chances are you don’t need a micronutrient supplement. However, in special cases, micronutrient supplementation could make sense. People with deficiencies often benefit more from micronutrient supplementation. For example, vitamin D supplementation is most beneficial for people with low baseline levels.[14] However, people with sufficient baseline levels showed only a slight risk reduction for acute respiratory infection. Another example is high-performing athletes, especially during periods of intensified training and/or competition. A Cochrane review[15] showed that marathon runners, skiers, and soldiers performing subarctic exercises showed a substantial risk reduction (RR 0.48) of getting a cold when supplementing vitamin C. If you are a high-performing athlete, this could make a practical difference to your performance.

    In general, beware of toxic overdosing and the potential side effects when supplementing minerals such as zinc[16] and water-insoluble vitamins such as vitamin D[17]. Overall, the usefulness of micronutrient supplementation most often requires individual consideration. Hence, it’s difficult to make any generalized recommendations.

    Which supplements can help against colds and the flu?
    Quick answer:

    Vitamin C, vitamin D, zinc, and other supplements may provide an edge against colds and the flu, but they should only serve to complement your main defensive arsenal: good hygiene, proper hydration, healthy diet, restful sleep, stress control, and exercise.

    Colds and the flu are caused by viruses that travel from person to person. Although you fend off infections year round, you may be more vulnerable during the colder months: the ambient cold may weaken your immune system, according to preliminary human[18] and animal[19] evidence, and if it makes you spend more time inside with other people, it also gives you more opportunities to trade viruses and microbes. image

    Unfortunately, even if you follow these best practices, you can still get unlucky and catch a cold or contract the flu. This is why, once winter hits, one of the most popular questions we get is: among the many supplements used to ward off an infection or lessen its symptoms, are there any that work?

    The answer is a tentative yes. In this article, we’ll review four supplements whose benefits are backed by moderate evidence and four whose benefits are backed by only preliminary evidence.

    Supplements with moderate evidence

    The evidence regarding the benefits of vitamin C, vitamin D, and zinc is often mixed, but it suggests a positive effect.

    Vitamin C

    Vitamin C is marketed as the go-to supplement for preventing and treating colds.

    Mechanistically, it makes sense: vitamin C helps immune cells form and function, and it supports the physical barriers (such as the epithelial cells of your skin) that protect you from pathogens.[20] Moreover, at least 148 animal studies have found that vitamin C administration helps prevent infections caused by microorganisms.[21]

    Those animal studies, however, don’t answer the question that most matters to us: can vitamin C supplementation help humans ward off colds? A 2013 Cochrane meta-analysis of human studies tried to answer this question,[15] and here are the takeaways:

    • People who start taking vitamin C when they already have a cold don’t appear to see much of a benefit. Some studies suggest that very high doses (several grams) might reduce the duration of colds, but more studies are needed for confirmation.
    • People who take vitamin C regularly can expect shorter colds (by 8% in adults and 14% in children) with slightly less severe symptoms.
    • Athletes who take vitamin C regularly are half as likely to catch a cold as athletes who don’t. Only people who “perform regular or acute bouts of intense exercise” seem to enjoy this benefit.

    A 2018 meta-analysis also supports the idea that vitamin C can shorten colds and lessen symptoms.[22] It included only 9 trials, however, all of which were among the 29 trials included in the 2013 Cochrane meta-analysis.

    Vitamin C can reduce the duration of colds (and even help ward them off, if you’re an athlete), but only if you’ve been supplementing regularly. If you start when you’re sick, it’s probably too late.

    Vitamin D

    Vitamin D receptors are found throughout the body, and vitamin D is involved in many cellular processes, including the regulation of immune cells during infections,[23][24] so it should come as no surprise that a deficiency can impair immunity.

    Epidemiological studies show an association between low vitamin D levels and a higher risk of viral infections of the upper respiratory tract (URT). [25][26] According to a 2017 systematic review and meta-analysis of individual participant data from randomised controlled trials, taking vitamin D could help prevent asthma symptoms as well as URT infections.[27] More may not be better, however: a randomized trial published the same year found no statistically significant difference in incidence and duration of URT viral infections between children taking 400 IU/day and children taking 2,000 IU/day.[28]

    Vitamin D serves many functions in the body, and a deficiency may impair immunity. A large systematic review suggests that supplementation may help prevent upper respiratory infections.

    Zinc

    Zinc plays many roles in the body — including several in the immune system alone. If you easily catch colds, make sure your diet provides you with enough zinc. Athletes and other people who sweat a lot are at greater risk of zinc insufficiency, but taking too much zinc is aso a risk, so be careful.

    Zinc lozenges can limit virus replication at the nasal epithelium and may reduce respiratory tract inflammation. Sucked throughout the day (75–95 milligrams of zinc per day, starting within 24 hours of symptom onset), they can reduce the duration of a cold by 2–4 days, though symptoms may persist for a few days thereafter.[29][30] Lozenges with zinc acetate may be more effective than lozenges with zinc gluconate (a more common form), but the trials are few, and a recent meta-analysis failed to find a significant difference.[31]

    Zinc lozenges can cause nausea and dysgeusia (a change in taste perception), but those symptoms stop when supplementation stops.[29][30] In addition to nausea and dysgeusia, zinc nasal sprays can cause anosmia,[32] and this loss of smell perception may persist after supplementation has stopped. For that reason, and because the sprays have not been shown to be more effective than the lozenges, the sprays are not recommended.

    The zinc dose shown to reduce the duration of colds (75–95 mg/day[29][30]) is above the safe upper limit (40 mg/day). You should suffer no harm if you take up to 100 mg/day for up to two weeks, but if you start suffering from nausea, vomiting, loss of appetite, stomach cramps, diarrhea, or headaches, all signs that you may be taking more zinc than your body can stand, just stop supplementing with zinc. Also, remember that zinc is present in foods and in many supplements, notably multivitamins: make sure that you don’t end up taking more zinc than you planned to.

    Taking zinc lozenges throughout the day, starting from the very first symptoms of a cold, may reduce the duration of the illness, but supplementation should not exceed 100 mg of zinc per day for up to two weeks. Since zinc nasal sprays might cause a lingering loss of smell perception, they’re better avoided.

    Supplements with preliminary evidence

    Many other supplements might help reduce the duration and severity of colds and the flu, but the evidence tends to be mixed, scarce, or low in quality. Among the most promising supplements are echinacea, elderberries, Pelargonium sidoides, and probiotics.

    Echinacea

    Taken daily, echinacea might reduce the risk and duration of upper respiratory infections,[33] yet trial effects are so small as to lack statistical or clinical significance.[34] Moreover, many of the trials were low in quality, or their quality was difficult to determine.

    Echinacea can interact with medications, particularly immunosuppressive drugs. If you take any medication, you may want to consult a physician before trying this supplement.

    Echinacea might reduce the risk and duration of upper respiratory infections, but many of the studies are of low quality and the effects are very small at best.

    Elderberries

    Elderberries (the fruits of the elderberry shrub) are known for their antioxidant properties, and in one randomized controlled trial, an elderberry extract reduced the duration and severity of colds more than placebo.[35] Also, a few human trials have shown elderberries to reduce symptoms of the flu,[36] but here the evidence is weakened by small sample sizes and, in some cases, low methodological quality.

    Due to the small number of studies, both the efficacy and safety of elderberries are still in doubt.[37] Should you choose to prepare elderberry juice yourself, rather than to purchase a supplement, remember that the berries must be properly cooked, since they can otherwise cause nausea or, worse, cyanide toxicity. Only ever use the berries — the rest of the plant is poisonous and should not be consumed in any form.

    Elderberries are a promising but understudied supplement: they may reduce the symptoms of colds and the flu, but the evidence is still preliminary. Beware: the plant is poisonous, and even the berries can be dangerous if not prepared properly.

    Pelargonium sidoides

    Pelargonium sidoides contains prodelphinidins — tannins that can help prevent bacteria from attaching to the lining of the throat and lungs. Pelargonium sidoides may reduce the duration and severity of colds,[38][39] but the studies are few and haven’t been critically appraised in systematic reviews. In addition, none of the studies were designed to see if Pelargonium sidoides could ward off colds.

    Pelargonium sidoides seems to reduce the duration and severity of colds, but the evidence is still preliminary.

    Probiotics

    Various probiotics have been shown to interact with immune system cells,[40] but a 2015 report summarizing 17 Cochrane systematic reviews found no high-quality evidence that probiotics could prevent illnesses.[41]

    Since then, a different systematic review and meta-analysis of 23 randomized controlled trials (RCTs) has found that probiotics appear to decrease the incidence of respiratory tract infections (RTIs) in children,[42] and two RCTs reported that specific probiotics might help prevent upper RTIs in athletes[43] and the elderly,[44] but the Cochrane reviews are still the most reliable evidence we have.

    Truth is, systematic reviews of probiotics studies are difficult to perform, for two reasons:

    • Different studies used different bacterial strains, so their comparability is low.
    • Some studies combined strains, making it impossible to determine which strain or strains caused the effects noted.

    With regards to the flu, a 2017 meta-analysis of 9 RCTs found that taking probiotics and/or prebiotics helped improve the efficacy of the flu vaccine in healthy adults when supplemented around the time of vaccination. However, many of the trial participants were healthy older adults, often above the age of 70, and we can’t be sure the benefits extend to a younger population.

    Probiotics might help prevent respiratory tract infections, but the evidence is of low quality. Several studies suggest that probiotics may increase the efficacy of the flu vaccine in healthy, older adults.

    Recommendations

    Reaching for a supplement or two can seem like a quick, simple way to defend yourself against colds and the flu. Be it for prevention or treatment, however, even taking the best supplements won’t help as much as following these best practices: image

    So, as always, choose efficacious supplements to complement your healthy habits — not to make up for a lifestyle that predisposes you to getting sick.

    If you’re looking for information on optimal dosages and combinations, then you may be interested in our Allergies & Immunity Supplement Guide.

    How could diet affect the common cold?

    Diet is mainly related to the common cold through immunity. Diets that are sufficient in energy, micronutrients, and macronutrients are important for maintaining a robust immune system, which will help reduce the risk and severity of common cold infections.[7] Flavonoids (plant compounds that have antioxidant and immunomodulatory properties; found in especially high quantities in tea, chocolate, capers, and oregano)[8] may be a noteworthy nutrient for this purpose.[9]

    Are there any other treatments for the common cold?

    Saline nasal and sinus irrigation (using devices like a neti pot or a nebulizer) may improve cold symptoms. However, it’s very important to only use water that has been filtered, sterilized, or otherwise treated for such uses — serious infections can occur otherwise.[10]

    Some trials report that meditation and exercise may reduce the risk and severity of the common cold.[11][12]

    What causes the common cold?

    The common cold is caused by a large number of viruses. Over 200 viruses have been identified as causing colds, many of which are classified as rhinoviruses. These viruses are constantly present in the environment, and infection can occur from physical contact with infected people or surfaces, breathing in small-particle aerosols containing virus in the air, or being directly hit by large-particle aerosols from a person coughing or sneezing.[13][1] Infections are most common in the winter and spring and during rainy seasons in tropical areas.[13]

    References

    1. ^Centers for Disease Control and PreventionCommon Cold
    2. ^The content of this page was partially adapted from MedlinePlus of the National Library of Medicine
    3. ^American Academy of Family PhysiciansColds and the Flu
    4. ^Kim SY, Chang YJ, Cho HM, Hwang YW, Moon YSNon-steroidal anti-inflammatory drugs for the common cold.Cochrane Database Syst Rev.(2015-Sep-21)
    5. ^Eccles REfficacy and safety of over-the-counter analgesics in the treatment of common cold and flu.J Clin Pharm Ther.(2006-Aug)
    6. ^Deckx L, De Sutter AI, Guo L, Mir NA, van Driel MLNasal decongestants in monotherapy for the common cold.Cochrane Database Syst Rev.(2016-Oct-17)
    7. ^Michael GleesonImmunological aspects of sport nutritionImmunol Cell Biol.(2016 Feb)
    8. ^Alhamzah Hasan Waheed Janabi, Asghar Ali Kamboh, Muhammad Saeed, Lu Xiaoyu, Jannat BiBi, Fatima Majeed, Muhammad Naveed, Muhammad Jameel Mughal, Nazar Ali Korejo, Rubina Kamboh, Mahmoud Alagawany, Huixia LvFlavonoid-rich foods (FRF): A promising nutraceutical approach against lifespan-shortening diseasesIran J Basic Med Sci.(2020 Feb)
    9. ^Vaughan S Somerville, Andrea J Braakhuis, Will G HopkinsEffect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-AnalysisAdv Nutr.(2016 May 16)
    10. ^National Institute of Health: National Center for Complementary and Integrative Health
    11. ^Rakel D, Mundt M, Ewers T, Fortney L, Zgierska A, Gassman M, Barrett BValue associated with mindfulness meditation and moderate exercise intervention in acute respiratory infection: the MEPARI Study.Fam Pract.(2013-Aug)
    12. ^Obasi CN, Brown R, Ewers T, Barlow S, Gassman M, Zgierska A, Coe CL, Barrett BAdvantage of meditation over exercise in reducing cold and flu illness is related to improved function and quality of life.Influenza Other Respir Viruses.(2013-Nov)
    13. ^Heikkinen T, Järvinen AThe common cold.Lancet.(2003-Jan-04)
    14. ^Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, Dubnov-Raz G, Esposito S, Ganmaa D, Ginde AA, Goodall EC, Grant CC, Griffiths CJ, Janssens W, Laaksi I, Manaseki-Holland S, Mauger D, Murdoch DR, Neale R, Rees JR, Simpson S Jr, Stelmach I, Kumar GT, Urashima M, Camargo CA JrVitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant dataBMJ.(2017 Feb 15)
    15. ^Hemilä H, Chalker EVitamin C for preventing and treating the common coldCochrane Database Syst Rev.(2013 Jan 31)
    16. ^Ulrika M. Agnew, Todd L. SlesingerZinc Toxicity
    17. ^Fahad Alshahrani, Naji AljohaniVitamin D: deficiency, sufficiency and toxicityNutrients.(2013 Sep 13)
    18. ^Mourtzoukou EG, Falagas MEExposure to cold and respiratory tract infectionsInt J Tuberc Lung Dis.(2007 Sep)
    19. ^Foxman EF, Storer JA, Fitzgerald ME, Wasik BR, Hou L, Zhao H, Turner PE, Pyle AM, Iwasaki ATemperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cellsProc Natl Acad Sci U S A.(2015 Jan 20)
    20. ^Carr AC, Maggini SVitamin C and Immune FunctionNutrients.(2017 Nov 3)
    21. ^Hemilä HVitamin C and InfectionsNutrients.(2017 Mar 29)
    22. ^Ran L, Zhao W, Wang J, Wang H, Zhao Y, Tseng Y, Bu HExtra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled TrialsBiomed Res Int.(2018 Jul 5)
    23. ^Brockman-Schneider RA, Pickles RJ, Gern JEEffects of vitamin D on airway epithelial cell morphology and rhinovirus replicationPLoS One.(2014 Jan 24)
    24. ^Telcian AG, Zdrenghea MT, Edwards MR, Laza-Stanca V, Mallia P, Johnston SL, Stanciu LAVitamin D increases the antiviral activity of bronchial epithelial cells in vitroAntiviral Res.(2017 Jan)
    25. ^Berry DJ, Hesketh K, Power C, Hyppönen EVitamin D status has a linear association with seasonal infections and lung function in British adultsBr J Nutr.(2011 Nov)
    26. ^Rafiq R, Thijs W, Prein R, de Jongh RT, Taube C, Hiemstra PS, de Mutsert R, den Heijer MAssociations of Serum 25(OH)D Concentrations with Lung Function, Airway Inflammation and Common Cold in the General PopulationNutrients.(2018 Jan 3)
    27. ^Martineau AR, et al.Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant dataBMJ.(2017)
    28. ^Aglipay M, Birken CS, Parkin PC, Loeb MB, Thorpe K, Chen Y, Laupacis A, Mamdani M, Macarthur C, Hoch JS, Mazzulli T, Maguire JL, TARGet Kids! CollaborationEffect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy ChildrenJAMA.(2017 Jul 18)
    29. ^Hemilä H, Petrus EJ, Fitzgerald JT, Prasad AZinc acetate lozenges for treating the common cold: an individual patient data meta-analysisBr J Clin Pharmacol.(2016 Nov)
    30. ^Hemilä H, Chalker EThe effectiveness of high dose zinc acetate lozenges on various common cold symptoms: a meta-analysisBMC Fam Pract.(2015 Feb 25)
    31. ^Hemilä HZinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosageJRSM Open.(2017 May 2)
    32. ^Alexander TH, Davidson TMIntranasal zinc and anosmia: the zinc-induced anosmia syndromeLaryngoscope.(2006 Feb)
    33. ^Shah SA, Sander S, White CM, Rinaldi M, Coleman CIEvaluation of echinacea for the prevention and treatment of the common cold: a meta-analysisLancet Infect Dis.(2007 Jul)
    34. ^Karsch-Völk M, Barrett B, Kiefer D, Bauer R, Ardjomand-Woelkart K, Linde KEchinacea for preventing and treating the common coldCochrane Database Syst Rev.(2014 Feb 20)
    35. ^Tiralongo E, Wee SS, Lea RAElderberry Supplementation Reduces Cold Duration and Symptoms in Air-Travellers: A Randomized, Double-Blind Placebo-Controlled Clinical TrialNutrients.(2016 Mar 24)
    36. ^Ulbricht C, Basch E, Cheung L, Goldberg H, Hammerness P, Isaac R, Khalsa KP, Romm A, Rychlik I, Varghese M, Weissner W, Windsor RC, Wortley JAn evidence-based systematic review of elderberry and elderflower (Sambucus nigra) by the Natural Standard Research CollaborationJ Diet Suppl.(2014 Mar)
    37. ^Holst L, Havnen GC, Nordeng HEchinacea and elderberry-should they be used against upper respiratory tract infections during pregnancy?Front Pharmacol.(2014 Mar 4)
    38. ^Fashner J, Ericson K, Werner STreatment of the common cold in children and adultsAm Fam Physician.(2012 Jul 15)
    39. ^Lizogub VG, Riley DS, Heger MEfficacy of a pelargonium sidoides preparation in patients with the common cold: a randomized, double blind, placebo-controlled clinical trialExplore (NY).(2007 Nov-Dec)
    40. ^Meng H, Lee Y, Ba Z, Peng J, Lin J, Boyer AS, Fleming JA, Furumoto EJ, Roberts RF, Kris-Etherton PM, Rogers CJConsumption of Bifidobacterium animalis subsp. lactis BB-12 impacts upper respiratory tract infection and the function of NK and T cells in healthy adultsMol Nutr Food Res.(2016 May)
    41. ^Braga VL, Rocha LPDS, Bernardo DD, Cruz CO, Riera RWhat do Cochrane systematic reviews say about probiotics as preventive interventions?Sao Paulo Med J.(2017 Nov-Dec)
    42. ^Wang Y, Li X, Ge T, Xiao Y, Liao Y, Cui Y, Zhang Y, Ho W, Yu G, Zhang TProbiotics for prevention and treatment of respiratory tract infections in children: A systematic review and meta-analysis of randomized controlled trialsMedicine (Baltimore).(2016 Aug)
    43. ^Strasser B, Geiger D, Schauer M, Gostner JM, Gatterer H, Burtscher M, Fuchs DProbiotic Supplements Beneficially Affect Tryptophan-Kynurenine Metabolism and Reduce the Incidence of Upper Respiratory Tract Infections in Trained Athletes: A Randomized, Double-Blinded, Placebo-Controlled TrialNutrients.(2016 Nov 23)
    44. ^Pu F, Guo Y, Li M, Zhu H, Wang S, Shen X, He M, Huang C, He FYogurt supplemented with probiotics can protect the healthy elderly from respiratory infections: A randomized controlled open-label trialClin Interv Aging.(2017 Aug 8)

    Examine Database References

    1. Upper Respiratory Tract Infection Risk - Tyrrell DA, Craig JW, Meada TW, White TA trial of ascorbic acid in the treatment of the common coldBr J Prev Soc Med.(1977 Sep)
    2. Upper Respiratory Tract Infection Risk - FRANZ WL, HEYL HL, SANDS GWBlood ascorbic acid level in bioflavonoid and ascorbic acid therapy of common coldJ Am Med Assoc.(1956 Nov 24)
    3. Upper Respiratory Tract Infection Risk - Lewis TL, Karlowski TR, Kapikian AZ, Lynch JM, Shaffer GW, George DAA controlled clinical trial of ascorbic acid for the common coldAnn N Y Acad Sci.(1975 Sep 30)
    4. Upper Respiratory Tract Infection Risk - Anderson TW, Reid DB, Beaton GHVitamin C and the common cold: a double-blind trialCan Med Assoc J.(1972 Sep 23)
    5. Upper Respiratory Tract Infection Risk - Pitt HA, Costrini AMVitamin C prophylaxis in marine recruitsJAMA.(1979 Mar 2)
    6. Upper Respiratory Tract Infection Risk - Schwartz AR, Togo Y, Hornick RB, Tominaga S, Gleckman RAEvaluation of the efficacy of ascorbic acid in prophylaxis of induced rhinovirus 44 infection in manJ Infect Dis.(1973 Oct)
    7. Upper Respiratory Tract Infection Risk - Constantini NW, Dubnov-Raz G, Eyal BB, Berry EM, Cohen AH, Hemilä HThe effect of vitamin C on upper respiratory infections in adolescent swimmers: a randomized trialEur J Pediatr.(2011 Jan)
    8. Upper Respiratory Tract Infection Risk - Anderson TW, Beaton GH, Corey P, Spero LWinter illness and vitamin C: the effect of relatively low dosesCan Med Assoc J.(1975 Apr 5)
    9. Upper Respiratory Tract Infection Risk - Carson M, Cox H, Corbett M, Pollitt NVitamin C and the common coldJ Soc Occup Med.(1975 Jul)
    10. Upper Respiratory Tract Infection Risk - Miller JZ, Nance WE, Norton JA, Wolen RL, Griffith RS, Rose RJTherapeutic effect of vitamin C. A co-twin control studyJAMA.(1977 Jan 17)
    11. Upper Respiratory Tract Infection Risk - Charleston SS, Clegg KMAscorbic acid and the common coldLancet.(1972 Jun 24)
    12. Upper Respiratory Tract Infection Risk - Ludvigsson J, Hansson LO, Tibbling GVitamin C as a preventive medicine against common colds in childrenScand J Infect Dis.(1977)
    13. Upper Respiratory Tract Infection Risk - Kim TK, Lim HR, Byun JSVitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised controlled trialBMJ Mil Health.(2020 Mar 5)
    14. Upper Respiratory Tract Infection Risk - Clegg KM, Macdonald JML-Ascorbic acid and D-isoascorbic acid in a common cold surveyAm J Clin Nutr.(1975 Sep)
    15. Upper Respiratory Tract Infection Risk - Elwood PC, Lee HP, St Leger AS, Baird M, Howard ANA randomized controlled trial of vitamin C in the prevention and amelioration of the common coldBr J Prev Soc Med.(1976 Sep)
    16. Upper Respiratory Tract Infection Risk - Van Straten M, Josling PPreventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled surveyAdv Ther.(2002 May-Jun)
    17. Upper Respiratory Tract Infection Risk - Karlowski TR, Chalmers TC, Frenkel LD, Kapikian AZ, Lewis TL, Lynch JMAscorbic acid for the common cold. A prophylactic and therapeutic trialJAMA.(1975 Mar 10)
    18. Upper Respiratory Tract Infection Risk - Carr AB, Einstein R, Lai LY, Martin NG, Starmer GAVitamin C and the common cold: a second MZ Cotwin control studyActa Genet Med Gemellol (Roma).(1981)
    19. Upper Respiratory Tract Infection Risk - Hunt C, Chakravorty NK, Annan GThe clinical and biochemical effects of vitamin C supplementation in short-stay hospitalized geriatric patientsInt J Vitam Nutr Res.(1984)
    20. Upper Respiratory Tract Infection Risk - Walker GH, Bynoe ML, Tyrrell DATrial of ascorbic acid in prevention of coldsBr Med J.(1967 Mar 11)
    21. Upper Respiratory Tract Infection Risk - Dahlberg G, Engel A, Rydin HThe Value of Ascorbic Acid as a Prophylactic against Common ColdsActa Medica Scandinavica.()
    22. Upper Respiratory Tract Infection Risk - Cowdan D, Diehl H, Baker ABVitamins For The Prevention Of ColdsJAMA.()
    23. Upper Respiratory Tract Infection Risk - Sabiston BH, Radomski MWHealth problems and vitamin C in Canadian northern military operations.()
    24. Upper Respiratory Tract Infection Symptoms - Hunt C, Chakravorty NK, Annan G, Habibzadeh N, Schorah CJThe clinical effects of vitamin C supplementation in elderly hospitalised patients with acute respiratory infectionsInt J Vitam Nutr Res.(1994)
    25. Upper Respiratory Tract Infection Symptoms - Audera C, Patulny RV, Sander BH, Douglas RMMega-dose vitamin C in treatment of the common cold: a randomised controlled trialMed J Aust.(2001 Oct 1)
    26. Upper Respiratory Tract Infection Symptoms - Elwood PC, Hughes SJ, Leger ASA randomized controlled trial of the therapeutic effect of vitamin C in the common coldPractitioner.(1977 Jan)
    27. Upper Respiratory Tract Infection Symptoms - Gorton HC, Jarvis KThe effectiveness of vitamin C in preventing and relieving the symptoms of virus-induced respiratory infectionsJ Manipulative Physiol Ther.(1999 Oct)
    28. Common Cold Symptoms - Ineffectiveness of vitamin C in treating coryza.Practitioner.(1968 Mar)
    29. Upper Respiratory Tract Infection Risk - Josling PPreventing the common cold with a garlic supplement: a double-blind, placebo-controlled surveyAdv Ther.(2001 Jul-Aug)
    30. Upper Respiratory Tract Infection Risk - Nantz MP, Rowe CA, Muller CE, Creasy RA, Stanilka JM, Percival SSSupplementation with aged garlic extract improves both NK and γδ-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition interventionClin Nutr.(2012 Jun)
    31. Upper Respiratory Tract Infection Risk - Martineau AR, Hanifa Y, Witt KD, Barnes NC, Hooper RL, Patel M, Stevens N, Enayat Z, Balayah Z, Syed A, Knight A, Jolliffe DA, Greiller CL, McLaughlin D, Venton TR, Rowe M, Timms PM, Clark D, Sadique Z, Eldridge SM, Griffiths CJDouble-blind randomised controlled trial of vitamin D3 supplementation for the prevention of acute respiratory infection in older adults and their carers (ViDiFlu)Thorax.(2015 Oct)
    32. Upper Respiratory Tract Infection Risk - Shimizu Y, Ito Y, Yui K, Egawa K, Orimo HIntake of 25-Hydroxyvitamin D3 Reduces Duration and Severity of Upper Respiratory Tract Infection: A Randomized, Double-Blind, Placebo-Controlled, Parallel Group Comparison StudyJ Nutr Health Aging.(2018)
    33. Upper Respiratory Tract Infection Risk - Laaksi I, Ruohola JP, Mattila V, Auvinen A, Ylikomi T, Pihlajamäki HVitamin D supplementation for the prevention of acute respiratory tract infection: a randomized, double-blinded trial among young Finnish menJ Infect Dis.(2010 Sep 1)
    34. Upper Respiratory Tract Infection Risk - Camargo CA, Sluyter J, Stewart AW, Khaw KT, Lawes CMM, Toop L, Waayer D, Scragg REffect of monthly high-dose vitamin D supplementation on acute respiratory infections in older adults: A randomized controlled trialClin Infect Dis.(2019 Aug 17)
    35. Upper Respiratory Tract Infection Risk - Goodall EC, Granados AC, Luinstra K, Pullenayegum E, Coleman BL, Loeb M, Smieja MVitamin D3 and gargling for the prevention of upper respiratory tract infections: a randomized controlled trialBMC Infect Dis.(2014 May 19)
    36. Upper Respiratory Tract Infection Risk - Jung HC, Seo MW, Lee S, Kim SW, Song JKVitamin D₃ Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled TrialInt J Environ Res Public Health.(2018 Sep 14)
    37. Upper Respiratory Tract Infection Risk - Camargo CA Jr, Ganmaa D, Frazier AL, Kirchberg FF, Stuart JJ, Kleinman K, Sumberzul N, Rich-Edwards JWRandomized trial of vitamin D supplementation and risk of acute respiratory infection in MongoliaPediatrics.(2012 Sep)
    38. Upper Respiratory Tract Infection Risk - Denlinger LC, King TS, Cardet JC, Craig T, Holguin F, Jackson DJ, Kraft M, Peters SP, Ross K, Sumino K, Boushey HA, Jarjour NN, Wechsler ME, Wenzel SE, Castro M, Avila PC, NHLBI AsthmaNet InvestigatorsVitamin D Supplementation and the Risk of Colds in Patients with AsthmaAm J Respir Crit Care Med.(2016 Mar 15)
    39. Upper Respiratory Tract Infection Risk - Prasad AS, Beck FW, Bao B, Fitzgerald JT, Snell DC, Steinberg JD, Cardozo LJZinc supplementation decreases incidence of infections in the elderly: effect of zinc on generation of cytokines and oxidative stressAm J Clin Nutr.(2007 Mar)
    40. Upper Respiratory Tract Infection Risk - Farr BM, Conner EM, Betts RF, Oleske J, Minnefor A, Gwaltney JM JrTwo randomized controlled trials of zinc gluconate lozenge therapy of experimentally induced rhinovirus coldsAntimicrob Agents Chemother.(1987 Aug)
    41. Upper Respiratory Tract Infection Risk - Al-Nakib W, Higgins PG, Barrow I, Batstone G, Tyrrell DAProphylaxis and treatment of rhinovirus colds with zinc gluconate lozengesJ Antimicrob Chemother.(1987 Dec)
    42. Upper Respiratory Tract Infection Symptoms - Hemilä HZinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosageJRSM Open.(2017 May 2)
    43. Upper Respiratory Tract Infection Symptoms - Godfrey JC, Conant Sloane B, Smith DS, Turco JH, Mercer N, Godfrey NJZinc gluconate and the common cold: a controlled clinical studyJ Int Med Res.(1992 Jun)
    44. Upper Respiratory Tract Infection Symptoms - Eby GA, Davis DR, Halcomb WWReduction in duration of common colds by zinc gluconate lozenges in a double-blind studyAntimicrob Agents Chemother.(1984 Jan)
    45. Upper Respiratory Tract Infection Symptoms - Prasad AS, Beck FW, Bao B, Snell D, Fitzgerald JTDuration and severity of symptoms and levels of plasma interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, and adhesion molecules in patients with common cold treated with zinc acetateJ Infect Dis.(2008 Mar 15)
    46. Upper Respiratory Tract Infection Symptoms - Hemilä H, Haukka J, Alho M, Vahtera J, Kivimäki MZinc acetate lozenges for the treatment of the common cold: a randomised controlled trialBMJ Open.(2020 Jan 23)
    47. Upper Respiratory Tract Infection Symptoms - Mossad SB, Macknin ML, Medendorp SV, Mason PZinc gluconate lozenges for treating the common cold. A randomized, double-blind, placebo-controlled studyAnn Intern Med.(1996 Jul 15)
    48. Upper Respiratory Tract Infection Symptoms - Turner RB, Cetnarowski WEEffect of treatment with zinc gluconate or zinc acetate on experimental and natural coldsClin Infect Dis.(2000 Nov)
    49. Upper Respiratory Tract Infection Symptoms - Prasad AS, Fitzgerald JT, Bao B, Beck FW, Chandrasekar PHDuration of symptoms and plasma cytokine levels in patients with the common cold treated with zinc acetate. A randomized, double-blind, placebo-controlled trialAnn Intern Med.(2000 Aug 15)
    50. Upper Respiratory Tract Infection Symptoms - Weismann K, Jakobsen JP, Weismann JE, Hammer UM, Nyholm SM, Hansen B, Lomholt KE, Schmidt KZinc gluconate lozenges for common cold. A double-blind clinical trialDan Med Bull.(1990 Jun)
    51. Upper Respiratory Tract Infection Symptoms - Petrus E, Lawson K, Bucci L, Blum KRandomized, double-masked, placebo-controlled clinical study of the effectiveness of zinc acetate lozenges on common cold symptoms in allergy-tested subjectsCurr Ther Res.()
    52. Upper Respiratory Tract Infection Risk - Turner RB, Riker DK, Gangemi JDIneffectiveness of echinacea for prevention of experimental rhinovirus coldsAntimicrob Agents Chemother.(2000 Jun)
    53. Upper Respiratory Tract Infection Risk - Turner RB, Bauer R, Woelkart K, Hulsey TC, Gangemi JDAn evaluation of Echinacea angustifolia in experimental rhinovirus infectionsN Engl J Med.(2005 Jul 28)
    54. Upper Respiratory Tract Infection Risk - Jawad M, Schoop R, Suter A, Klein P, Eccles RSafety and Efficacy Profile of Echinacea purpurea to Prevent Common Cold Episodes: A Randomized, Double-Blind, Placebo-Controlled TrialEvid Based Complement Alternat Med.(2012)
    55. Upper Respiratory Tract Infection Risk - Linde K, Barrett B, Wölkart K, Bauer R, Melchart DEchinacea for preventing and treating the common coldCochrane Database Syst Rev.(2006 Jan 25)
    56. Upper Respiratory Tract Infection Risk - Grimm W, Müller HHA randomized controlled trial of the effect of fluid extract of Echinacea purpurea on the incidence and severity of colds and respiratory infectionsAm J Med.(1999 Feb)
    57. Upper Respiratory Tract Infection Risk - David S, Cunningham REchinacea for the prevention and treatment of upper respiratory tract infections: A systematic review and meta-analysisComplement Ther Med.(2019 Jun)
    58. Upper Respiratory Tract Infection Risk - Schoop R, Klein P, Suter A, Johnston SLEchinacea in the prevention of induced rhinovirus colds: a meta-analysisClin Ther.(2006 Feb)
    59. Upper Respiratory Tract Infection Risk - Sperber SJ, Shah LP, Gilbert RD, Ritchey TW, Monto ASEchinacea purpurea for prevention of experimental rhinovirus coldsClin Infect Dis.(2004 May 15)
    60. Upper Respiratory Tract Infection Risk - Shah SA, Sander S, White CM, Rinaldi M, Coleman CIEvaluation of echinacea for the prevention and treatment of the common cold: a meta-analysisLancet Infect Dis.(2007 Jul)
    61. Upper Respiratory Tract Infection Risk - Taylor JA, Weber W, Standish L, Quinn H, Goesling J, McGann M, Calabrese CEfficacy and safety of echinacea in treating upper respiratory tract infections in children: a randomized controlled trialJAMA.(2003 Dec 3)
    62. Upper Respiratory Tract Infection Risk - O'Neil J, Hughes S, Lourie A, Zweifler JEffects of echinacea on the frequency of upper respiratory tract symptoms: a randomized, double-blind, placebo-controlled trialAnn Allergy Asthma Immunol.(2008 Apr)
    63. Upper Respiratory Tract Infection Symptoms - Goel V, Lovlin R, Chang C, Slama JV, Barton R, Gahler R, Bauer R, Goonewardene L, Basu TKA proprietary extract from the echinacea plant (Echinacea purpurea) enhances systemic immune response during a common coldPhytother Res.(2005 Aug)
    64. Upper Respiratory Tract Infection Symptoms - Yale SH, Liu KEchinacea purpurea therapy for the treatment of the common cold: a randomized, double-blind, placebo-controlled clinical trialArch Intern Med.(2004 Jun 14)
    65. Upper Respiratory Tract Infection Symptoms - Barrett B, Brown R, Rakel D, Mundt M, Bone K, Barlow S, Ewers TEchinacea for treating the common cold: a randomized trialAnn Intern Med.(2010 Dec 21)
    66. Upper Respiratory Tract Infection Symptoms - Schulten B, Bulitta M, Ballering-Brühl B, Köster U, Schäfer MEfficacy of Echinacea purpurea in patients with a common cold. A placebo-controlled, randomised, double-blind clinical trialArzneimittelforschung.(2001)
    67. Upper Respiratory Tract Infection Symptoms - Goel V, Lovlin R, Barton R, Lyon MR, Bauer R, Lee TD, Basu TKEfficacy of a standardized echinacea preparation (Echinilin) for the treatment of the common cold: a randomized, double-blind, placebo-controlled trialJ Clin Pharm Ther.(2004 Feb)
    68. Upper Respiratory Tract Infection Symptoms - Brinkeborn RM, Shah DV, Degenring FHEchinaforce and other Echinacea fresh plant preparations in the treatment of the common cold. A randomized, placebo controlled, double-blind clinical trialPhytomedicine.(1999 Mar)
    69. Upper Respiratory Tract Infection Symptoms - Barton R, Tapan B, Lyon MEfficacy of a standardized echinacea preparation (EchinilinTM) for the treatment of the common cold: a randomized, double-blind, placebo-controlled trialJ Clin Pharm Ther.()
    70. Upper Respiratory Tract Infection Risk - Meydani SN, Leka LS, Fine BC, Dallal GE, Keusch GT, Singh MF, Hamer DHVitamin E and respiratory tract infections in elderly nursing home residents: a randomized controlled trialJAMA.(2004 Aug 18)
    71. Upper Respiratory Tract Infection Risk - Crooks C, Cross ML, Wall C, Ali AEffect of bovine colostrum supplementation on respiratory tract mucosal defenses in swimmersInt J Sport Nutr Exerc Metab.(2010 Jun)
    72. Upper Respiratory Tract Infection Symptoms - Cáceres DD, Hancke JL, Burgos RA, Sandberg F, Wikman GKUse of visual analogue scale measurements (VAS) to asses the effectiveness of standardized Andrographis paniculata extract SHA-10 in reducing the symptoms of common cold. A randomized double blind-placebo studyPhytomedicine.(1999 Oct)
    73. Upper Respiratory Tract Infection Symptoms - Patiroglu T, Tunc A, Eke Gungor H, Unal EThe efficacy of Pelargonium sidoides in the treatment of upper respiratory tract infections in children with transient hypogammaglobulinemia of infancyPhytomedicine.(2012 Aug 15)
    74. Common Cold Symptoms - Lizogub VG, Riley DS, Heger MEfficacy of a pelargonium sidoides preparation in patients with the common cold: a randomized, double blind, placebo-controlled clinical trialExplore (NY).(2007 Nov-Dec)
    75. Common Cold Symptoms - Pach D, Knöchel B, Lüdtke R, Wruck K, Willich SN, Witt CMVisiting a sauna: does inhaling hot dry air reduce common cold symptoms? A randomised controlled trial.Med J Aust.(2010)
    76. Nasal Congestion - Taverner D, Danz C, Economos DThe effects of oral pseudoephedrine on nasal patency in the common cold: a double-blind single-dose placebo-controlled trialClin Otolaryngol Allied Sci.(1999 Feb)
    77. Nasal Congestion - Eccles R, Jawad MS, Jawad SS, Angello JT, Druce HMEfficacy and safety of single and multiple doses of pseudoephedrine in the treatment of nasal congestion associated with common coldAm J Rhinol.(2005 Jan-Feb)
    78. Nasal Congestion - Loose I, Winkel MClinical, double-blind, placebo-controlled study investigating the combination of acetylsalicylic acid and pseudoephedrine for the symptomatic treatment of nasal congestion associated with common coldArzneimittelforschung.(2004)
    79. Oxidative Stress Biomarkers - Hanwell HE, Kay CD, Lampe JW, Holub BJ, Duncan AMAcute fish oil and soy isoflavone supplementation increase postprandial serum (n-3) polyunsaturated fatty acids and isoflavones but do not affect triacylglycerols or biomarkers of oxidative stress in overweight and obese hypertriglyceridemic menJ Nutr.(2009 Jun)
    80. Vaccine Augmentation - Scaglione F, Cattaneo G, Alessandria M, Cogo REfficacy and safety of the standardised Ginseng extract G115 for potentiating vaccination against the influenza syndrome and protection against the common cold correctedDrugs Exp Clin Res.(1996)