Kava (Piper methysticum G. Forst)

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. Currently, pharmaceutical preparations of the herb are widely used in Europe and the U.S. as anxiolytics, but have recently been withdrawn from several European markets due to safety concerns.

Several well-conducted human trials and a meta-analysis have demonstrated kava's efficacy in the treatment of anxiety, with effects observed after as few as 1-2 doses, and progressive improvements over 1-4 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 hepatotoxicity of kava. More than 30 cases of liver damage have been reported in Europe, including hepatitis, cirrhosis, and fulminant liver failure. Kava has been removed from shelves in several countries due to these safety concerns. The U.S. Food & Drug Administration 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

Ava, ava pepper, ava pepper shrub, ava root, awa, cavain, gea, gi, intoxicating long pepper, intoxicating pepper, kao, kavakava, kava kava rhizome, kavapiper, kavarod, kava root, kavain, kave-kave, kawa, kawa kawa, kawa pepper, Kawa Pfeffer, kew, malohu, maluk, maori kava, meruk, milik, pepe kava, piperis methystici rhizoma, Rauschpfeffer, rhizoma piperis methystici, 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 evidenceGrade*Anxiety
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. 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 U.S. Food & Drug Administration has issued warnings to consumers and physicians. Many products have been pulled from the market.

A

* 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 (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

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, antifungal, antipsychotic, aphrodisiac, arthritis, asthma, birth control, cancer, brain damage, colds, cystitis, depression, diuretic, dizziness, gonorrhea, hemorrhoids, infections, jet lag, joint pain and stiffness, kidney disorders, leprosy, menopause, menstrual disorders, migraine headache, pain, premenstrual syndrome (PMS), Premenstrual Dysphoric Disorder (PMDD), 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.

Standardization

Standardization involves measuring the amount of certain chemicals in products to try to make different preparations similar to each other. It is not always known if the chemicals being measured are the "active" ingredients. Kava extract is typically standardized to 30% kava lactones. The actual lactone content of the root can vary between 3 to 20%. Many brands use the standardized preparation WS 1490. A review of standardized kava brands in the United States found 50 to 110 milligrams kava lactones per tablet/capsule. Actual (measured) and labeled amounts of kava lactones were approximately equal in 13 products.

Adults (18 years and older)

Anxiety : 300 milligrams of kava extract daily (standardized WS 1490 preparation) taken by mouth in three divided doses has been found beneficial in human studies. Typical doses range from 70 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.

Side Effects and Warnings

Until recently, kava was generally thought to be safe when used over short periods of time (one to two months) at recommended doses. Two brief studies of several thousand patients taking either 105 milligrams daily of a 75% kavalactone extract or 800 milligrams daily of a 30% kavalactone extract reported side effects only in a small number of subjects (1.5% to 2.3%). Side effects were primarily gastrointestinal (stomach) upset, allergic rash, or mild headache. However, there have now been numerous reports of severe liver problems in people using kava. More than 25 cases of liver toxicity, including liver failure, have been reported following use of kava in Europe. Two cases in Switzerland involved one specific brand (Leitan®, Schwabe, Germany). In heavy kava users, abnormal blood levels of liver enzymes have occurred. It is not clear what dose or duration of use may raise the risk of liver damage, in part because most case reports have been vague or included patients who also drink large amounts of alcohol. The United States Food & Drug Administration has issued warnings to consumers and physicians, and has requested that physicians report cases of liver toxicity that may be related to kava use. Although many natural medicine experts still believe that kava is safe at recommended doses, there is not enough scientific information to make a clear conclusion. Therefore, kava should be used only under the supervision of a qualified healthcare provider, should never be used above recommended doses, and should be avoided by people with liver problems or taking drugs that affect the liver.

Other serious side effects have been observed with chronic or heavy use of kava, including skin disorders, blood abnormalities, abnormal muscle movements, apathy, kidney damage, seizures, psychotic syndromes, and increased blood pressure in the lungs (pulmonary hypertension). The skin disorders observed with chronic use of kava are commonly called "kava dermopathy" (or kani in Fiji). Dry, scaly skin or yellow skin discoloration may occur. The effects seem to be reversible upon stopping use. The blood disorders observed with chronic and heavy kava use include increased red blood cell size, reduced blood platelet size, reduced white blood cell number, and reduced blood protein levels. Blood in the urine has also been reported.

Several cases of abnormal muscle movements have been reported after short-term use of kava (one to four days), including tightening, twisting, or locking of the muscles of the mouth, neck (torticollis) and eyes (oculogyric crisis). Worsening of symptoms of Parkinson's disease, and several cases of abnormal whole body movements (choreoathetosis) following high doses of kava have also been noted. Tremor, poor coordination, headache, drowsiness, and fatigue have uncommonly been reported, particularly with large doses. A case of muscle cell breakdown (rhabdomyolysis) was reported in a 29-year-old man after taking an herbal combination of ginkgo, guarana, and kava.

Sedation (drowsiness) has occasionally been reported with kava use, although there is early evidence from several small human studies that kava may not significantly cause this effect. In two human studies, no effect of kava on motor vehicle driving performance was found. However, there have been two cases in the state of California of drivers being arrested for "driving under the influence" after drinking kava tea (neither case resulted in successful prosecution). Because this issue remains unclear, driving and operating heavy machinery is not recommend while taking kava.

Eye disturbances and eye irritation have rarely been associated with chronic or heavy kava use. There is one report of impaired eye focus, and increased pupil size following one-time use. Rapid heart rate, electrocardiogram (ECG) abnormalities, and shortness of breath have been reported in heavy kava users, perhaps having to do with abnormally high blood pressure in the lungs (pulmonary hypertension). Laboratory tests suggest that kava may increase the risk of bleeding through effects on blood platelets. However, human evidence is lacking in this area, and there are no reports of significant bleeding in the scientific literature.

Pregnancy & Breastfeeding

Use of kava cannot be recommended during pregnancy or breastfeeding. There may be decreases in the muscle strength of the uterus with the use of kava, which may have harmful effects on pregnancy. Chemicals in kava may pass into breast milk with unknown effects, and therefore this herb should be avoided during breastfeeding.

References

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January 01, 2004