Herb library · Herb · Piper methysticum
Kava
A South Pacific pepper-family root, drunk for thousands of years and sold today mostly for anxiety. Some research suggests it may help anxiety, but kava products have been linked to rare, sometimes fatal liver injury.
Serious warning
Kava has been linked to rare cases of liver injury, some serious or fatal (NCCIH), including kava drinks made with water. LiverTox calls kava a well-known cause of liver injury: cases have ended in liver failure, liver transplant, and death.
Traditional use
Pacific Islanders have used kava beverages for thousands of years for ceremonial and medicinal purposes. The drink is now sold at kava bars in the United States, and kava is sold as a dietary supplement (and in some countries as a drug) for anxiety, insomnia, and stress. LiverTox notes that kava has been banned or restricted in several countries because of liver injury reports.
What studies show
- Limited
Anxiety: a fair amount of research suggests kava supplements may help anxiety, possibly only after several weeks of use.
- Limited· shows no benefit
Generalized anxiety disorder: kava does not appear to help its symptoms.
- Insufficient
Other conditions: there isn't enough evidence to show whether kava helps.
Be careful of
Cautions
- ConditionLiverTox reports that liver injury typically shows up 2 to 24 weeks after starting, with fatigue, nausea, and yellowing of the skin or eyes. Stop kava and get medical care if these appear.
- InteractionDo not combine kava with other substances that cause sedation, such as benzodiazepines or alcohol.
- AmountLong-term use of high doses can cause kava dermopathy: dry, scaly, flaking skin, reddened eyes, and yellowing of the skin, hair, and nails.
- NoteKava can cause upset stomach, headache, dizziness, and other side effects.
- PregnancyKava may carry special risks in pregnancy and breastfeeding because of harmful pyrone constituents.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
From the old books
What herbals and dispensaries of the past printed. History, in their words.
“The action of the root varies, according to the amount taken; in small doses, it is tonic and stimulant; while in large doses it produces an intoxication, which, unlike that from alcohol, is of a reserved, drowsy character, and attended with confused dreams.”
“The natives who use its infusion as an intoxicating beverage for a considerable length of time, are said to become affected with a dry, scaly, cracked, and ulcerated skin, and vision becomes more or less obscured.”
Sources
- Kava: Usefulness and Safety (opens in a new tab) · NCCIH · read September 25, 2026
- Kava Kava (LiverTox) (opens in a new tab) · NIH · read September 25, 2026
Reviewed September 25, 2026.