Other common name(s): kava-kava, kavalactones
Scientific/medical name(s): Piper methysticum
Kava is a large shrub with broad, heart-shaped leaves, a member of the same family as black pepper (the Piperaceae family). It is native to many Pacific islands, including New Guinea, Fiji, Tahiti, Samoa, Tonga, and Hawaii. The roots of the plant are used in herbal remedies and for ceremonies or rituals.
Some studies support the use of kava for reducing anxiety, and it is widely used to help with sleep. It may have several effects on the brain, some of which are similar to prescription tranquilizers. The safe dosage of kava needed to reduce anxiety is uncertain. Reports of more than 50 cases of severe liver impairment in people taking kava supplements have led several countries to ban or restrict sales of kava. Some of the patients had liver transplants and some died. Side effects appear to increase with larger doses taken over longer periods of time. Kava appears to increase the effects of some medicines and can interfere with anesthesia as well.
How is it promoted for use?
Kava supplements are promoted mainly for anxiety, nervous tension, stress, restlessness, and, at higher doses, sleeplessness. Many users say the herb improves mood and brings on a sense of well-being, relaxation, and even euphoria.
In South Pacific folk medicine, a drink made from the kava root has been used to treat uterine inflammation, headaches, colds, rheumatism, and menopausal symptoms. In these traditional settings, the kava root is chewed, ground, or beaten, then soaked in cold water or coconut milk. Users drink the liquid to relieve headaches, restore vigor, promote urination, soothe upset stomachs, ease symptoms of asthma and tuberculosis, and cure fungal infections. Some users believe that kava inhibits the growth of the gonorrhea bacteria. The leaves and branches of the kava plant are sometimes applied to the skin. Kava creams are used to soothe stings and inflamed skin.
Kava is not promoted as an anti-cancer treatment. While its reputation for easing mild anxiety may be of interest to people with cancer, there are many effective prescription medicines and many non-medical treatments (including complementary mind-body methods) for anxiety that patients can discuss with their doctors.
What does it involve?
Kava is available as a tablet, capsule, cream, and as a powder, which can be made into tea or mixed with other drinks. Daily doses range from 50 to 240 milligrams of kavalactones (the active ingredient in kava). For anxiety, it may be taken several times a day. For sleep, it is taken about an hour before bedtime.
Kava dietary supplements are made by using solvents to extract kavalactones from kava roots. There are reports that some manufacturers have also used the peelings from kava stems, which contain a possible toxin. Differences in quality and type of ingredients and methods of extraction mean that the kava used as a dietary supplement is not the same as the kava used in the traditional Fijian, Samoan, and Tongan cultures. There is some question about whether the differences between the plant as used traditionally and kava dietary supplements may account for the rare but extreme cases of toxicity that have been linked to supplements.
Because of reports of liver failure caused by kava supplements, Germany, France, the United Kingdom, the Netherlands, Canada, and Switzerland have all banned or restricted kava. The US Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention have issued warnings about liver failure to US consumers.
What is the history behind it?
The people of the South Pacific have used kava socially, ceremonially, and medicinally for thousands of years. A beverage prepared from the kava root is traditionally offered to visiting royalty and dignitaries and served at meetings of village elders. The drink is also often shared at social gatherings.
Accounts of kava first came to the West from the English naval officer Captain James Cook, who encountered the plant during a trip to Polynesia in the 1770s. Interest in kava spread quickly. Kava first underwent medical investigation in the 1860s and by the end of the 19th century, kava preparations were available in German pharmacies.
What is the evidence?
Kava has been the focus of dozens of medical studies, some of which support claims made about the herb’s usefulness for mild anxiety. Kava appears to ease symptoms of tension, nervousness, and stress. In recent studies, patients with varying levels of anxiety took kava extract, and many reported relief within days or weeks. It does not appear to be very effective in those with moderate to severe anxiety.
Some researchers have found that kava compares well to prescription anti-anxiety medicines. In clinical studies, it caused few side effects and did not appear to be addictive. One study showed that kava did not impair reaction time and even improved concentration. In comparison, common prescription drugs for anxiety slow reaction time. In other recent clinical trials, however, kava was no more effective than placebo in treating anxiety or insomnia.
Exactly how kava works is still uncertain. Some scientists think that kava works in the brain in a similar way to the group of prescription tranquilizers called benzodiazepines. In addition, it appears to block dopamine, which may explain how it can produce a sensation of pleasure. It may also act in other parts of the brain and other organs.
More research is needed on long-term use and safe dosing. Studies are also needed to find out whether the cases of liver failure were caused by the way the kava was processed or by the kava root itself, and whether the problem can be addressed so that these serious effects can be avoided in the future.
Are there any possible problems or complications?
This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must provide the FDA with results of detailed testing showing their product is safe and effective before the drug is approved for sale), the companies that make supplements do not have to show evidence of safety or health benefits to the FDA before selling their products. Supplement products without any reliable scientific evidence of health benefits may still be sold as long as the companies selling them do not claim the supplements can prevent, treat, or cure any specific disease. Some such products may not contain the amount of the herb or substance that is written on the label, and some may include other substances (contaminants). Though the FDA has written new rules to improve the quality of manufacturing processes for dietary supplements and the accurate listing of supplement ingredients, these rules do not take full effect until 2010. And, the new rules do not address the safety of supplement ingredients or their effects on health when proper manufacturing techniques are used.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.
In rare cases, kava can lead to liver failure and other life-threatening problems. Even moderate use can lead to abnormal organ function, including increased levels of liver enzymes. According to the FDA, people who have had liver problems and those taking medications that may affect the liver, such as cholesterol-lowering drugs, should check with their doctors before taking kava. The FDA further recommends that kava be stopped if symptoms of liver disease, such as jaundice (marked by brown urine and yellowing of the eyes or skin) occur. Other symptoms of liver disease include nausea, vomiting, light-colored stools, unusual tiredness, weakness, stomach pain, and loss of appetite. People who drink alcohol regularly have a higher risk of liver damage.
Kava may affect reflexes and judgment, so it should not be used by people driving or operating heavy machinery. Other side effects of kava include severe involuntary movements, headache, upset stomach, drowsiness, trouble breathing, poor appetite, weight loss, scaly skin, red eyes, abnormal blood cells, blood in the urine, poor coordination, and muscle weakness. Kava may worsen symptoms in people who have Parkinson’s disease, seizures, depression, or bipolar disorder. Studies have not been done on children or women who are pregnant or breast-feeding, and no safety data is available. Although rare, some allergic reactions to kava have been reported.
Kava should not be taken with drugs that cause drowsiness, such as anti-anxiety medicines, muscle relaxants, sedatives, pain relievers, or alcohol, due to the risk of extreme drowsiness or even unconsciousness. People taking antidepressants or drugs that affect dopamine (such as haloperidol, risperidone, metoclopramide, or l-dopa) should not use kava. Those taking blood-thinning medications may have increased risk of bleeding. Because of its potential to interact with anesthetics, people who are planning to have surgery should stop taking it for 2 to 3 weeks before surgery. In addition, other potential interactions between kava and other drugs and herbs should be considered. Always tell your doctor and pharmacist about any herbs you are taking.
A safe dosage of kava has not been determined. Kava should not be taken for more than 4 weeks unless recommended by a doctor. Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.
More information from your American Cancer Society
The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-ACS-2345).
The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management
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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.
Last Revised: 11/28/2008