Kava-kava (also simply called kava) has a long history of medicinal and ceremonial use on the islands of the South Pacific, where this mildly intoxicating beverage is consumed for its relaxation effects. Made from the root of a tall shrub in the pepper family (Piper methysticum), kava is also sold in capsules (in powdered form) and tinctures (liquid extracts) and is marketed to relieve anxiety, stress, and sleeplessness, among other uses. A systematic review by the independent Cochrane Collaboration in 2010 concluded that, "Compared with placebo, kava extract is an effective symptomatic treatment for anxiety, although, at present, the size of the effect seems small." More rigorous and larger trials are needed.
Rare cases of severe liver damage—with at least four people requiring liver transplants—were linked to the use of kava in Europe more than 10 years ago, possibly due to mold contamination of the raw materials. It was subsequently withdrawn for sale in some European countries and Canada. The FDA issued a consumer advisory about its liver-related risks at the time, but did not restrict its sales. Like any intoxicant, kava can impair driving; combining alcohol and kava increases the adverse effects.
Our take: The risks of kava outweigh any benefits, especially if you have any kind of liver condition or take medication that can affect liver function. Other names kava may go by on supplement labels include kawa, ava, kew, tonga, yangona, and intoxicating pepper. If you suffer from ongoing anxiety or sleep problems, consult your health care provider, rather than take kava.