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Kava (Piper methysticum)

Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain kava. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with a pharmacist or health care professional before starting.


Scientists have studied kava for the following health problem:

Multiple studies suggest that kava lessens anxiety.

However, there are numerous reports of serious side effects or death following the use of kava, and the herb has been banned in many countries and removed from stores. It is not clear if these side effects occur only with high doses, with long-term use or in people with pre-existing liver damage. Until better safety information is available, kava cannot be recommended unless it is used under the strict supervision of a qualified health care professional. Natural Standard has collaborated with the World Health Organization (WHO) to prepare a detailed report of kava and associated adverse effects.
Early study results suggest that kava and valerian may be beneficial to health by reducing physiological reactivity during stressful situations and stress-induced insomnia. Further research is needed to confirm these results.
Parkinson's disease
Kava has been shown to increases "off" periods in Parkinson patients taking levodopa and can cause a semicomatose state when given with alprazolam. Therefore, it is not recommended.

Unproven Uses    

Kava has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult with a health care professional before taking kava for any unproven use.

Anticraving agent (addiction)
Birth control
Bust enhancement
Inflammation of the ear
Inflammation of the uterus
Jet lag
Kidney stones
Menstrual problems
Migraine headache
Muscle relaxant
Parasite infections
Premenstrual syndrome
Premenstrual dysphoric disorder
Protection of brain tissue against ischemic damage
Respiratory tract infections
Urinary tract problems
Vaginal prolapse
Weight loss
Wound healing

Potential Dangers    


Side Effects

Pregnancy And Breast-Feeding


Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with a health care professional or pharmacist before using herbs or dietary supplements.

Interactions With Drugs

Interactions With Herbs And Dietary Supplements

Kava may increase the amount of drowsiness caused by some herbs or supplements, such as valerian. Caution is advised while driving or operating machinery. In theory, kava may add to the effects of herbs and supplements that act like monoamine oxidase inhibitor drugs, such as evening primrose oil.


The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care professional before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.

Adults (Aged 18 Or Older)

Children (Younger Than 18):  Kava should not be given to children because safety and effectiveness are not known.


Multiple studies suggest that kava lessens anxiety. Scientific evidence does not support the use of kava for any other conditions. There have been recent reports of serious liver damage or death in people using kava. It is not clear if these problems occurred at high doses or after long-term use. Therefore, kava should be used only under the supervision of a qualified health care professional. Kava should never be taken at doses higher than recommended or for longer than two months. Kava should be avoided in people with liver disease, Parkinson's disease or lung disease; in pregnant or breast-feeding women; and in children. It should not be used in people taking monoamine oxidase inhibitors or drugs that may damage the liver or cause drowsiness. Consult a health care professioal immediately if you have side effects.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.


  1. Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
  2. National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research

Selected Scientific Studies: Kava
Natural Standard reviewed more than 425 articles to prepare the professional monograph from which this version was created.

Some of the more recent studies are listed below:

  1. Almeida JC, Grimsley EW. Coma from the health food store: interaction between kava and alprazolam. Ann Intern Med 1996;125(11):940-941.
  2. Boerner RJ, Sommer H, Berger W, et al. Kava-kava extract LI 150 is as effective as opipramol and buspirone in generalised anxiety disorder: an 8-week randomized, double-blind multi-centre clinical trial in 129 out-patients. Phytomedicine 2003;10(Suppl 4):38-49.
  3. Brauer RB, Stangl M, Stewart JR, et al. Acute liver failure after administration of herbal tranquilizer kava-kava (Piper methysticum). J Clin Psychiatry 2003;Feb, 64(2):216-218.
  4. Cagnacci A, Arangino S, Renzi A, et al. Kava-kava administration reduces anxiety in perimenopausal women. Maturitas 2003;Feb 25, 44(2):103-109.
  5. Cairney S, Clough AR, Maruff P, et al. Saccade and cognitive function in chronic kava users. Neuropsychopharmacology 2003;Feb, 28(2):389-396.
  6. Campo JV, McNabb J, Perel JM, et al. Kava-induced fulminant hepatic failure. J Am Acad Child Adolesc Psychiatry 2002;Jun, 41(6):631-632.
  7. Clough AR, Wang Z, Bailie RS, et al. Case-control study of the association between kava use and pneumonia in eastern Arnhem and Aboriginal communities (Northern Territory, Australia). Epidemiol Infect 2003;Aug, 131(1):627-635.
  8. Clough AR, Jacups SP, Wang Z, et al. Health effects of kava use in an eastern Arnhem Land Aboriginal community. Int Med J 2003;Aug, 33(8):336-340.
  9. Connor KM, Davidson JR. A placebo-controlled study of kava kava in generalized anxiety disorder. Int Clin Psychopharmacol 2002;Jul, 17(4):185-188.
  10. Cropley M, Cave Z, Ellis J, Middleton RW. Effect of kava and valerian on human physiological and psychological responses to mental stress assessed under laboratory conditions. Phytother Res 2002;Feb, 16(1):23-27.
  11. Currie BJ, Clough AR. Kava hepatotoxicity with Western herbal products: does it occur with traditional kava use? Med J Aust 2003;May 5, 178(9):421-422. Comment in: Med J Aust 2003;May 5, 178(9):442-423. Med J Aust 2003;May 5, 178(9):451-453.
  12. De Smet PA. Safety concerns about kava not unique. Lancet 2002;Oct 26, 360(9342):1336. Comment in: Lancet 2002;May 25, 359(9320):1865.
  13. Dietlein G, Schroder-Bernhardi D. Doctors' prescription behaviour regarding dosage recommendations for preparations of kava extracts. Pharmacoepidemiol Drug Saf 2003;Jul-Aug, 12(5):417-421.
  14. Ernst E. Safety concerns about kava. Lancet 2002;May 25, 359(9320):1865. Comment in: Lancet 2002;Oct 26, 360(9342):1336.
  15. Escher M, Desmeules J, Giostra E, et al. Hepatitis associated with kava, a herbal remedy for anxiety. BMJ 2001;322(7279):139.
  16. Estes JD, Stolpman D, Olyaei A, et al. High prevalence of potentially hepatotoxic herbal supplement use in patients with fulminant hepatic failure. Arch Surg 2003;Aug, 138(8):852-858.
  17. Gow PJ, Connelly NJ, Hill RL, et al. Fatal fulminant hepatic failure induced by a natural therapy containing kava. Med J Aust 2003;May 5, 178(9):442-443. Comment in: Med J Aust 2003;May 5, 178(9):421-422.
  18. Humberston CL, Akhtar J, Krenzelok EP. Acute hepatitis induced by kava kava. J Toxicol Clin Toxicol 2003;41(2):109-113.
  19. Jappe U, Franke I, Reinhold D, et al. Sebotropic drug reaction resulting from kava-kava extract therapy: a new entity? J Am Acad Dermatol 1998;38(1):104-106.
  20. Patra KK, Coffey CE. Implications of herbal alternative medicine for electroconvulsive therapy. J ECT 2004;20(3):186-194.
  21. Pittler MH, Ernst E. Efficacy of kava extract for treating anxiety: systematic review and meta-analysis. J Clin Psychopharmacol 2000;20(1):84-89.
  22. Russmann S, Lauterburg BH, Helbling A. Kava hepatotoxicity. Ann Intern Med 2001;135(1):68-69.
  23. Scherer J. Kava-kava extract in anxiety disorders: an outpatient observational study. Adv Ther 1998;15(4):261-269.
  24. Schmidt P, Boehncke WH. Delayed-type hypersensitivity reaction to kava-kava extract. Contact Dermatitis 2000;42(6):363-364.
  25. Steiner GG. Kava as an anticraving agent: preliminary data. Pac Health Dialog 2001;8(2):335-339.
  26. Stevenson C, Huntley A, Ernst E. A systematic review of the safety of kava extract in the treatment of anxiety. Drug Saf 2002;25(4):251-261.
  27. Sun J. Morning/evening menopausal formula relieves menopausal symptoms: a pilot study. J Altern Complement Med 2003;9(3):403-409.
  28. Thompson R, Ruch W, Hasenohrl RU. Enhanced cognitive performance and cheerful mood by standardized extracts of Piper methysticum (Kava-kava). Hum Psychopharmacol 2004;19(4):243-250.
  29. Volz HP, Kieser M. Kava-kava extract WS 1490 versus placebo in anxiety disorders: a randomized placebo-controlled 25-week outpatient trial. Pharmacopsychiatry 1997;30(1):1-5.
  30. Wheatley D. Stress-induced insomnia treated with kava and valerian: singly and in combination. Hum Psychopharmacol 2001;16(4):353-356.

Last updated July 13, 2005