Research review
Ashwagandha and kava: what the research does and doesn't show
No trial has tested ashwagandha and kava together. Each has its own separately documented case reports of liver injury, which is the main reason to be cautious about combining them rather than assuming two separate safety profiles simply add up to nothing.
No published trial has tested ashwagandha and kava taken together. Each has its own research, studied separately — and each has its own separately documented case reports of liver injury, which matters more here than the fact that nobody has combined them in a trial. Two supplements that each carry a liver-injury signal on their own isn't a combination to assume is fine by default.
What the evidence doesn't support
It doesn't support ashwagandha and kava, together or separately, as a treatment for a diagnosed anxiety disorder. It doesn't support the idea that combining two calming-adjacent supplements adds up to a larger or safer effect than either alone — that pairing has never been studied. And it doesn't support treating either ingredient's liver-safety profile as resolved just because the other one is unrelated botanically; each has its own case reports, and using both increases the number of substances a liver has to process at once.
What the trials found
Kava (Piper methysticum) has its own randomized trial history for anxiety, separate from ashwagandha's. A 16-week, placebo-controlled trial of a standardized kava extract (120 mg kavalactones twice daily) in 171 adults with diagnosed generalized anxiety disorder found no significant difference in anxiety reduction between kava and placebo. In that same trial, liver function test abnormalities were significantly more common in the kava group than placebo — though no single case met the formal criteria for herb-induced liver injury — and tremor/shakiness and poorer memory were also reported more often with kava.
Outside controlled trials, kava has a well-documented history of case reports of liver injury, serious enough that several countries restricted or banned kava products in the early 2000s before some restrictions were later eased. A 2025 case report describes a 46-year-old man who developed acute hepatocellular liver injury (ALT over 1,500 U/L) after taking 10 g of kava a day for 5 weeks to help him sleep; a liver biopsy confirmed hepatocellular necrosis, and an updated causality score rated kava the "probable" cause. His liver enzymes returned to normal after he stopped.
Ashwagandha carries a parallel, more recently documented safety signal: case reports of "probable" liver injury, including one at a daily dose close to what a typical ashwagandha product delivers (see is ashwagandha bad for your liver? for the specifics). Neither ingredient's case reports establish how common liver injury actually is in the wider population who takes them — case reports can't do that — but they are real, and they exist for both ingredients independently. No study has looked at what happens when both are taken at once.
Questions people ask
Is ashwagandha like kava?
Not really. They're unrelated plants studied for different traditional uses — kava for a short-term calming effect, ashwagandha for a broader set of traditional uses including stress and sleep. Their proposed mechanisms are different, and the clinical trial evidence for each stands on its own; neither is a substitute for the other, and neither is a treatment for a diagnosed anxiety disorder.
Can you take ashwagandha and kava together?
No trial has tested it. Given that both ingredients have their own separate case reports of liver injury, combining them is a question worth raising with a doctor first, particularly if you drink alcohol regularly, take any medication processed by the liver, or have any history of liver problems.
Kava vs ashwagandha — which is safer?
Neither has a large enough body of safety data to rank one as clearly safer than the other. Kava's liver-injury case history is longer-documented and was significant enough to prompt regulatory restrictions in several countries; ashwagandha's is a more recent finding. Both are reasons for caution rather than reassurance, and neither replaces a conversation with a doctor about what's already being taken.
When to talk to a doctor
Anxiety that interferes with daily life is worth raising with a doctor rather than addressing with a supplement search — neither ashwagandha nor kava is a treatment for generalized anxiety disorder or any other diagnosed condition. Stop and see a doctor for any sign of liver trouble — yellowing skin or eyes, dark urine, unusual fatigue, or pain under the right ribs — whether taking one of these ingredients or both. If you take medication, drink alcohol regularly, or have a liver condition, talk to a doctor before combining any two supplements, this pair included.
Related reading: is ashwagandha bad for your liver?, who should not take ashwagandha, and ashwagandha and medications: what to check.
Sources
- Herb-Induced Liver Injury by Ayurvedic Ashwagandha as Assessed for Causality by the Updated RUCAM: An Emerging Cause Two adults taking 450 mg ashwagandha capsules (one at 1,350 mg/day) developed liver injury judged 'probably' caused by the supplement, resolving after stopping it.
- Kava Herb-Induced Liver Injury as Verified by the Updated RUCAM A 46-year-old man developed liver injury judged 'probably' caused by kava after taking 10 g/day for 5 weeks, resolving after he stopped.
- Kava for generalised anxiety disorder: A 16-week double-blind, randomised, placebo-controlled study In a 16-week placebo-controlled trial of 171 adults with diagnosed generalized anxiety disorder, a standardized kava extract did not reduce anxiety more than placebo, and liver enzyme abnormalities were more common in the kava group even though no case met formal injury criteria.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.