Kava: Traditional Use, Research and Liver Safety

Quick answer

Kava is a drink and supplement made from the root of a Pacific plant, Piper methysticum. It is not a classic psychedelic. It is a relaxing, mildly sedating plant used for ceremony and social life in the Pacific. The main safety issue regulators and the NIH raise is rare but sometimes severe liver injury. Evidence labels used here: promising but limited, mixed, insufficient evidence.

Traditional and cultural context

Kava is native to the South Pacific and belongs to the pepper family. Pacific Islanders have used kava beverages for thousands of years for ceremonial and medicinal purposes. [1] A 2020 FDA review describes kava as drunk ceremonially and socially in the South Pacific for many centuries, and says migrants carried the practice to places such as New Caledonia, the Solomon Islands, Kiribati and New Zealand. [2]

Kava is part of living cultures, not only a product. Respect for that context matters when the same plant is sold as a supplement or served in bars elsewhere. See Indigenous traditions, ethics and conservation for the wider discussion.

How it is sold

In the United States kava products are sold as dietary supplements, and kava drinks are served at kava bars. In some other countries kava is sold as a drug or herbal medicine. [1] Supplements are not approved by the FDA before sale. [1]

What research shows

Anxiety: mixed. The NIH says kava supplements may help anxiety but may need several weeks to work, and that kava does not appear to help generalized anxiety disorder. [1] Two Australian trials of one water-based extract show why:

• A 6-week trial (58 people analyzed) found a moderate benefit over placebo for generalized anxiety disorder. [3]
• A larger 16-week trial (171 people) found no significant difference from placebo. [4]

Other conditions: insufficient evidence. The NIH says there is not enough evidence to show whether kava helps any other condition. [1]

Liver safety

Various kava products have been linked to rare cases of liver injury, some serious or even fatal. [1] The first reported cases involved products made with alcohol or acetone, but other cases involved kava beverages prepared with water. [1] The NIH notes several theories, including plant variety or plant part, drinking kava with alcohol, product contamination, individual genetic differences, and large amounts or long use. None is settled. [1]

What regulators did:

• The FDA issued a consumer advisory and a letter to health professionals in 2002 about liver damage. [2]
• The same FDA review says safety concerns led to withdrawal or bans in several European markets and in Canada since 2002. It also says kava remained on sale in the US as a supplement. [2] That review dates from 2020, so check current rules where you live.

In the 16-week trial, liver test abnormalities were more frequent on kava than placebo, although no participant met criteria for herb-induced liver injury. [4]

Other side effects and interactions

Kava can cause digestive upset, headache and dizziness. Long-term use of high doses may cause kava dermopathy, with dry, scaly skin, reddened eyes and temporary yellow discoloration of the skin, hair and nails. [1] In the long trial, poorer memory and tremor or shakiness were reported more often on kava. [4]

Kava should not be combined with other sedating substances such as benzodiazepines or alcohol. [1] Anyone who takes medicines should talk with a health professional first. [1]

Who should be especially careful

• People with liver disease or on medicines that affect the liver: see liver safety and supplements.
• Pregnancy and breastfeeding: the NIH says kava may carry special risks because of harmful pyrone constituents. [1]
• Anyone taking sedatives, sleep medicines or drinking alcohol. [1]

This page gives no amounts or preparation advice. Kava products vary widely, and liver injury has not been tied to a single product type.

Related reading

Medication interactions, talking with a health professional, herb safety and interactions and kratom, a different plant often mentioned alongside kava.