Kava

Is kava safe?

Kava is the root of a Pacific pepper plant, drunk for centuries in Fiji, Vanuatu, Tonga and Samoa for its calming effect. As a traditional drink made with water, it has a long record of social use. As a concentrated supplement, its record is much worse: around 2000 to 2002, a run of severe liver injuries in Europe and the US led several countries to pull it from sale.

We score kava 43, in the weak band. The main reasons are liver toxicity that is rare but severe, a strong interaction with alcohol and sedatives, and the fact that some major markets still ban it.

The liver cases

The cases began appearing in Germany and Switzerland in the late 1990s. In December 2002, the CDC summarised the picture: patients aged 14 to 61 developed liver failure after taking kava products, and liver transplants were needed in two people in the US (a 45-year-old woman and a 14-year-old girl), six in Germany and two in Switzerland. The European cases had taken 60 to 240 mg a day, ordinary doses, for between eight weeks and a year.

By then, regulators had collected around 70 reports worldwide of jaundice, hepatitis, cirrhosis and liver failure, with several deaths. The NIH's LiverToxLiverToxA free US National Institutes of Health database that summarises what is known about liver injury caused by medicines, herbs and supplements.More in the glossary database lists kava as a cause of clinically apparent acute liver injuryDrug-induced liver injuryLiver damage caused by a medicine, herbal product or supplement. It is usually rare and unpredictable, but it can be serious.More in the glossary.

Why kava harms some livers and not others is still debated. A World Health Organization review pointed to product quality: extracts made with acetone or ethanol rather than water, and products using stems, leaves or root peelings rather than peeled root. Others suspect differences between plant varieties. None of these explanations has been proven, which is why the risk cannot be designed out.

The 2002 crackdown and what has changed

Year	Country	Action
2002	US	FDA consumer advisory on liver injuryDrug-induced liver injuryLiver damage caused by a medicine, herbal product or supplement. It is usually rare and unpredictable, but it can be serious.More in the glossary (25 March)
2002	Germany	Medicine licences withdrawn (June)
2002	Canada	Stop-sale and recall (August)
2003	UK	Kava banned in food (January)
2019	Australia	Pilot allowing commercial imports as food
2022	Codex	Regional standard for kava drinks
2024	Germany	Court ruled against the restrictions; regulator appealed

The trend since about 2015 has been to separate traditional drinks from concentrated extracts. Australia now imports hundreds of tonnes as food, and Pacific producers have pushed for international quality standards. Germany's courts ruled against the restrictions on kava medicines in 2014 and again in June 2024, but the regulator appealed and the licences remained suspended while the case continued. The UK ban has not been reviewed.

Interactions

Kava's main active compounds, kavalactones, act on the brain in ways that add to other sedatives:

• Alcohol: more sedation and impairment, and possibly more liver risk.
• Benzodiazepines, sleeping pills, opioids, antihistamines: excessive drowsiness. A case of coma with alprazolam has been reported.
• Drugs that can harm the liver, such as paracetamol in high doses, some statins and antifungals.
• Levodopa: kava may reduce its effect in Parkinson's disease.

Kava also inhibits several CYP liver enzymes, which could raise levels of other medicines. Show your medicine list to a pharmacist before taking it.

Other effects

At usual doses, kava causes drowsiness and can impair driving. Heavy, long-term drinking causes kava dermopathy, a dry, scaly yellowish skin that clears when people stop. There are no safety data in pregnancy or breastfeeding.

If you still want to use kava

• Do not use it if you have liver disease, drink alcohol regularly or take any sedative.
• Choose a traditional water-based drink made from peeled root of a noble variety over concentrated capsules or tinctures.
• Limit use to short periods and ask your doctor about a liver test if you use it regularly.
• Stop immediately and see a doctor if you develop yellow skin or eyes, dark urine, pale stools, nausea or unexplained tiredness.
• Do not drive or operate machinery after taking it.

People using kava for anxiety or sleep may be considering ashwagandha too, which carries its own, smaller liver signal.

How we scored it

Organ toxicity (30) and regulatory actions (30) are the weakest factors: transplants, deaths and bans in major markets. Interactions (45) and quality (50) are weak because kava adds to sedatives and products vary widely. Dose safety (55) is the strongest factor, and even that is only fair. Only kratom scores lower in this section.