From the Guidelines
Kava is associated with a risk of acute fatal liver toxicity, and its use is strongly advised against due to the potential for serious harm. According to the most recent and highest quality study available, 1, the U.S. Food and Drug Administration has warned health care providers and the public about the risk for acute liver damage and death associated with kava. Several cases of severe liver injury, including some requiring liver transplantation, have been reported in connection with kava use, leading to bans or restrictions in several countries. The liver damage appears to be idiosyncratic (unpredictable and not dose-dependent) and may involve genetic factors or interactions with medications.
Some key points to consider:
- The risk of liver damage seems higher with products using stems and leaves rather than just the root, with alcohol or acetone extracts rather than traditional water extracts, and when taken with alcohol or other medications that stress the liver.
- If you choose to use kava, minimize risk by using only traditional water-based preparations of the root, avoiding alcohol while using it, not taking it with medications that affect the liver, and stopping use if you experience symptoms like yellowing skin or eyes, dark urine, light-colored stools, fatigue, or abdominal pain.
- People with existing liver problems, those who drink alcohol regularly, or those taking medications metabolized by the liver should be especially cautious or avoid kava entirely.
- The evidence supporting the use of kava for treatment of chronic insomnia disorder is lacking, and the potential benefits do not outweigh the risks of liver damage and other adverse effects, as noted in the study 1.
From the Research
Kava and Hepatic Injury
- Kava has been associated with hepatic injury in several case reports and studies 2, 3, 4, 5.
- A case report published in 2003 described a 14-year-old female who developed acute hepatitis after taking a kava kava-containing product for four months, and ultimately required a liver transplant 2.
- A review of kava hepatotoxicity published in 2010 discussed possible pathogenetic factors for the development of kava-induced liver injury, including metabolic interactions, genetic enzyme deficiencies, and toxic constituents and metabolites derived from the kava extract 3.
- Another study published in 2010 suggested that kava hepatotoxicity may be caused by poor quality of the kava raw material, and proposed a six-point plan for new kava standardization to prevent kava hepatotoxicity 4.
- A clinical review published in 2010 analyzed the clinical data of patients with suspected kava hepatotoxicity and suggested recommendations for minimizing risk, including standardization of kava extracts and avoidance of comedication with synthetic drugs and dietary supplements 5.
Contrasting Evidence
- A study published in 2007 found that kava feeding in rats did not cause liver injury nor enhance galactosamine-induced hepatitis, suggesting that kava may not be hepatotoxic in all cases 6.
- This study used two types of kava extracts and three different doses, and found no liver injury based on serum markers of liver damage and liver histology analysis 6.
Possible Causes of Hepatic Injury
- Overdose and prolonged treatment with kava have been identified as risk factors for hepatic injury 3, 5.
- Comedication with synthetic drugs and dietary supplements, including herbal ones, may also increase the risk of hepatic injury 3, 5.
- Poor quality of the kava raw material, including the use of inappropriate kava plant parts and unsuitable kava cultivars, may contribute to the development of hepatic injury 3, 4.