Kava kava (Piper methysticum) has been used as a ceremonial drink in the Pacific Islands for hundreds of years. It has been reported to have an effect similar to an alcoholic drink.
The roots are chewed or ground into a pulp and added to cold water. The resulting thick brew, which has been compared to the social equivalent of wine in France, is offered to guests and dignitaries visiting the Pacific Islands.
In addition to its ceremonial uses, kava is best known for its relaxing qualities. Kava is said to elevate mood, well-being, and contentment, and produce a feeling of relaxation. Several studies have found that kava may be useful in the treatment of anxiety, insomnia, and related nervous disorders.
However, there is serious concern that kava may cause liver damage. More than 30 cases of liver damage have been reported in Europe. It's not clear whether the kava itself was the cause of the liver damage or whether it was taking kava in combination with other drugs or herbs. It's also not clear whether kava is dangerous at previously recommended doses, or only at higher doses. Some countries have taken kava off the market. It remains available in the United States, but the Food and Drug Administration (FDA) issued a consumer advisory in March of 2002 regarding the "rare" but potential risk of liver failure associated with kava-containing products. (See "Precautions" section.)
Because it is impossible to say what -- if any -- dose of kava might be safe, you should not take kava unless you are under a doctor's close supervision.
Kava is a tall shrub that grows in the islands of the Pacific Ocean. This shrub produces large, green, heart-shaped leaves that grow thickly on the branches. Long, slender flowers grow where the branches meet the stems. The roots look like bundles of woody, hairy branches. The root is the part of the plant used medicinally.
Medicinal Uses and Indications
Because kava may cause liver damage, you should not use it unless you are under a doctor's supervision. Evidence suggests kava may be helpful for the following health problems:
A number of clinical studies -- though not all -- have found kava kava to be effective in treating symptoms associated with anxiety. In a review of seven scientific studies, researchers concluded that a standardized kava extract was significantly more effective than placebo in treating anxiety. Another study found that kava substantially improved symptoms after only 1 week of treatment. Another study found that kava may be as effective as some prescription anti-anxiety medications. In fact, according to one study, kava and diazepam (Valium) cause similar changes in brain wave activity, suggesting that they may work in the same ways to calm the mind.
Research on using kava for anxiety has decreased because of reports of liver toxicity.
A 2004 study found that 300 mg of kava may improve mood and cognitive performance. That is significant because some prescription drugs used to treat anxiety, such as benzodiazepines (like Valium and alprazolam or Xanax), tend to decrease cognitive function.
There is some preliminary evidence that kava may help improve sleep quality and decrease the amount of time needed to fall asleep. However, more studies would be needed to say for sure. Because of the concerns about kava's safety and the fact that other herbs can treat sleeplessness, kava is not the best choice for treating insomnia.
What's It Made Of?
The main active ingredients in kava root are called kavalactones (kavapyrones). These chemicals (including kawain, dihydrokawain, and methysticum) have been extensively studied in laboratory and animal studies. They have been found to reduce convulsions, promote sleep, and relax muscles in animals. They also have pain-relieving properties, which may explain why chewing kava root tends to cause a temporary numbness and tingling sensation on the tongue.
In some parts of the world, whole kava roots are chewed for their medicinal value. Kava is also available in liquid form, as tinctures or standardized extracts, and powdered in capsules or tablets.
How to Take It
Because some people have developed severe liver damage, even liver failure, after taking kava you should only take it under a doctor's close supervision (See "Precautions" section). If you have liver disease (such as cirrhosis or hepatitis), you should not take kava at all.
Kava should not be given to children.
The doses listed below are the ones used in most studies. However, given reports of liver damage, it is now impossible to say what dose of kava may be considered safe. That is why it is important to have your doctor determine any dose of kava you may take.
Standardized dosage: 150 - 300 mg, 1 - 3 times daily as needed for anxiety or nervousness, standardized to contain 30 - 70 % kavalactones. Most clinical trials have used the German kava extract WS 1490.
Kava dried root: 2.0 - 4.0 grams as a decoction (a preparation made by boiling down the herb in water), up to 3 times daily.
It may take 4 weeks before you notice improvement. Kava should not be taken for more than 3 months without a 2-week rest period.
The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, contain components that can trigger side effects and interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care provider qualified in the field of botanical medicine. This is particularly true for kava, because there is evidence it may cause liver damage.
Reports in the United States and Europe have linked kava with severe liver problems. Kava-containing products have been associated with at least 25 reports of liver-related injuries (including hepatitis, cirrhosis, liver failure, and death). In one case report, a 50-year-old man developed hepatitis after taking three to four kava extracts daily for 2 months. His condition quickly deteriorated, and he needed a liver transplant.
There is much we don't know about kava's effect on the liver. It may be that the kava supplements some people took were contaminated with other substances that caused liver damage. Or it is possible that some people already had liver problems before taking kava, or that they took a combination of kava and other prescription medications or herbs that damaged their livers. It is also possible that the doses generally recommended for kava affect people differently, so that a dose that would cause liver damage in one person might have no effect on the liver in another person.
Because of the uncertainty around kava, you should only take it with your doctor's supervision. If you have taken kava and are experiencing symptoms of liver damage [such as yellow skin (jaundice), fatigue, abdominal pain, loss of appetite, nausea, vomiting, and joint pain], seek immediate medical attention.
People with liver damage should not take kava.
Pregnant or breastfeeding women should not take kava.
Do not take kava if you are going to have surgery (and tell your surgeon if you have taken it in the past). Kava can prolong the effect of anesthesia.
Do not drink alcohol and take kava.
Other side effects associated with kava include allergic skin reactions (such as contact dermatitis), dizziness, drowsiness, restlessness, stomach upset, and tremors. Long-term use at high doses may cause flaky, dry, and yellowish discoloration of the skin, hair loss (alopecia), partial loss of hearing, and loss of appetite. Like alcohol, kava may have intoxicating effects and should not be taken before operating a car or other machinery.
Do not take kava unless you are under the supervision of a doctor, especially if you are being treated for any disease. Do not take kava with any prescription and non-prescription medications.
Kava kava may interact with the following:
Anticonvulsants -- Kava may increase the effects of medications, such as phenytoin (Dilantin), that are used to treat seizures.
Alcohol -- Do not use kava and alcohol together. The risk of impairment and the risk of liver damage are greatly increased.
Anti-anxiety agents -- Kava may increase the effects of CNS depressants such as benzodiazepines, used for sleep disturbances or anxiety (particularly alprazolam or Xanax), and barbiturates (such as pentobarbital) which are used for sleep disorders and seizures. Benzodiazepines include:
- Alprazolam (Xanax)
- Diazepam (Valium)
- Lorazepam (Ativan)
- Triazolam (Halcion)
- Chlordiazepoxide (Librium)
Diuretics (water pills) -- These drugs help rid the body of excess fluid. Kava can make the effects of these drugs stronger, raising the risk of dehydration.
Phenothiazine medications -- Kava may increase the risk of side effects associated with phenothiazine medications (often used for the treatment of schizophrenia), including chlorpromazine (Thorazine); and promethazine (Phenergan), which is used as an antihistamine.
Levodopa -- There has been at least one report that kava may reduce the effectiveness of levodopa, a medication used to treat Parkinson's disease. You should not take kava if you are taking any medications containing levodopa or if you have Parkinson's disease.