Kava (Piper methysticum G. Forst)
Background
Kava beverages, made from dried roots of the shrub Piper methysticum , have been used ceremonially and socially in the South Pacific for hundreds of years, and in Europe since the 1700s.
Several well-conducted human studies have demonstrated kava's efficacy in the treatment of anxiety, with effects observed after as few as one to two doses, and progressive improvements over one to four weeks. Preliminary evidence suggests possible equivalence to benzodiazepines.
Many experts believe that kava is neither sedating nor tolerance-forming in recommended doses. Some trials report occasional mild sedation, although preliminary data from small studies suggest lack of neurological-psychological impairment.
There is growing concern regarding the potential for liver toxicity from kava. Multiple cases of liver damage have been reported in Europe, including hepatitis, cirrhosis, and liver failure. Kava has been removed from shelves in several countries due to these safety concerns. The United States Food and Drug Administration (FDA) has issued warnings to consumers and physicians. It is not clear what dose or duration of use is correlated with the risk of liver damage. The quality of these case reports has been variable; several are vague, describe use of products that do not actually list kava as an ingredient, or include patients who also ingest large quantities of alcohol. Nonetheless, caution is warranted.
Chronic or heavy use of kava has also been associated with cases of neurotoxicity, pulmonary hypertension, and dermatologic changes. Most human trials have been shorter than two months, with the longest study being six months in duration.
Synonyms
(+) -dihydrokawain-5-ol, 11-methoxy-5, 5-hydroxydihydrokawain, 6-dihydroyangonin, Antares, ava pepper, ava pepper shrub, ava root, awa, bornyl cinnamate, cavain, flavokavines A and B, gea, gi, intoxicating long pepper, intoxicating pepper, kao, kavakava, kava kava extract LI 140, kava kava rhizome, kavapiper, kavarod, kava root, kavasporal forte, kavain, kave-kave, kawa, kawa kawa, kawa pepper, Kawa Pfeffer, kew, Macropiper latifolium, malohu, maluk, maori kava, meruk, milik, pepe kava, Piper methysticum, pipermethystine, piperis methystici rhizoma, Rauschpfeffer, rhizoma piperis methystici, sakau, sakua, tonga, yagona, yangona, yaqona.
Evidence
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
| Uses based on scientific evidence | Grade* |
Anxiety Human studies have found at least moderate benefit of kava in the treatment of anxiety, and preliminary evidence suggests that kava may be equivalent to benzodiazepine drugs such as diazepam (Valium®). Kava's effects were reported to be similar to the prescription drug buspirone (Buspar®) used for Generalized Anxiety Disorder (GAD) in one study. However, there is concern regarding kava's potential toxicity, based on multiple reports of liver damage in Europe and a number of cases in the U.S., including hepatitis, cirrhosis, and liver failure. The US FDA has issued warnings to consumers and physicians. Many products have been pulled from the market. Natural Standard has collaborated with the World Health Organization (WHO) to prepare a detailed report of kava and associated adverse effects, which will be published soon. | A |
Stress 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. | C |
Parkinson's disease Kava has been shown to increase 'off' periods in Parkinson patients taking levodopa and can cause a semicomatose state when given with alprazolam. Therefore, it is not recommended. | D |
*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.
Grading rationale
Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Anesthesia, anorexia, anticraving agent (addiction), antifungal, antipsychotic, aphrodisiac, arthritis, asthma, birth control, brain damage, bust enhancement, cancer, colds, cystitis, depression, diuretic, dizziness, gonorrhea, hemorrhoids, infections, jet lag, joint pain and stiffness, kidney disorders, leprosy, menopause, menstrual disorders, migraine headache, neuroprotective, pain, premenstrual syndrome (PMS), premenstrual dysphoric disorder (PMDD), protection of brain tissue against ischemic damage, seizures, spasm, stomach upset, syphilis, toothache, tuberculosis, urinary tract disorders, uterus inflammation, vaginal prolapse, vaginitis, weight reduction, wound healing.
Dosing
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
Adults (18 years and older)
300 milligrams of kava extract daily (standardized WS 1490 preparation) taken by mouth in three divided doses has been found beneficial in human studies for anxiety. Typical doses range from 50 to 280 milligrams of kava lactones daily, as a single bedtime dose or in divided doses, using a lower dose first and increasing slowly if necessary. Doses as high as 800 milligrams daily of kava extract have been taken for short periods, but have not been studied over the long term, and safety is not clear.
Children (younger than 18 years)
There is not enough scientific evidence to recommend the use of kava in children.
Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Allergies
Allergic skin rashes have occasionally been reported.
