Ashwagandha and Your Liver and Kidneys: Is It Safe?

Ashwagandha has become one of the most popular adaptogens in American gyms and wellness routines, marketed for stress, sleep and even testosterone. At the same time, reports of liver injury linked to the herb have prompted regulators in several countries to take a closer look. Our editorial team weighed the evidence on ashwagandha's effects on the liver and kidneys and what it means for everyday users.

What ashwagandha is and how it is used

Ashwagandha (Withania somnifera) is a shrub used for centuries in Ayurvedic medicine. Its root, and sometimes its leaves, contain withanolides, steroidal lactones considered the main active compounds, along with alkaloids and other constituents.

Modern clinical trials have mostly tested standardized root extracts at doses around 250–600 mg per day for periods of six to twelve weeks. Several randomized studies report reductions in perceived stress and serum cortisol, modest improvements in sleep quality, and in some training studies small gains in strength.

In the US, ashwagandha is sold as a dietary supplement. Products vary considerably in plant part, extraction method and withanolide content, which makes comparing them difficult and complicates safety assessment.

Short-term trials generally report good tolerability, with mild digestive upset, drowsiness and headache as the most frequent complaints. Concerns arose from real-world use, where people take products for longer, combine them with other supplements, and sometimes have unrecognized risk factors.

Liver injury: what the case reports show

The US National Institutes of Health LiverTox database lists ashwagandha as a likely, though rare, cause of clinically apparent liver injury. Published case series, including reports from the US Drug-Induced Liver Injury Network and from Iceland, describe patients who developed jaundice, itching and markedly elevated liver enzymes after weeks to months of use.

The typical pattern is cholestatic or mixed liver injury, often appearing two to twelve weeks after starting the supplement. In most published cases, liver tests returned to normal after stopping ashwagandha, though recovery could take several months. A small number of severe cases, including liver failure, have been reported.

The mechanism is unknown. It is not clear whether the problem lies with specific withanolides, contamination, adulteration, product variability or individual susceptibility. Because many patients took multi-ingredient products, attributing injury to ashwagandha alone is not always straightforward.

Regulators have reacted differently. Denmark moved to restrict ashwagandha products in 2023 based on a risk assessment, and several other European authorities issued warnings. The FDA has not banned it, but the existence of these reports means users should take symptoms seriously.

Kidneys: what we know and do not know

Unlike the liver, there is no consistent signal of kidney damage from ashwagandha in human studies. Clinical trials measuring creatinine and other kidney markers over several weeks generally found no clinically meaningful changes.

Some animal studies have even suggested protective effects against certain kidney toxins, but these findings cannot be applied directly to people and should not be used as a reason to take the herb for kidney health.

Caution is still warranted for people with existing chronic kidney disease. Data in this group are essentially absent, and any supplement that is processed by the body adds an unknown variable for patients with reduced kidney function or on complex drug regimens.

Liver injury itself can, in severe cases, affect kidney function, which is another reason to stop the supplement and seek care quickly if symptoms of liver trouble appear.

Who should be cautious

Anyone with existing liver disease, including fatty liver disease, hepatitis or a history of drug-induced liver injury, should avoid ashwagandha unless a hepatologist approves. The same applies to people who drink alcohol heavily.

Those taking medications that stress the liver, such as acetaminophen at high doses, certain antifungals, statins or isoniazid, should discuss the combination with a physician. Combining several herbal products also increases the difficulty of identifying a culprit if problems arise.

Because ashwagandha may raise thyroid hormone levels, people with hyperthyroidism or on thyroid medication should be monitored. It is also not recommended during pregnancy, as traditional texts and some reports associate it with miscarriage risk.

• Existing liver disease or prior drug-induced liver injury
• Heavy alcohol use
• Use of hepatotoxic medications or multiple herbal products
• Thyroid disorders, autoimmune diseases, pregnancy
• Chronic kidney disease, due to lack of data

Practical safety steps

If you decide to use ashwagandha, choose a standardized root extract from a manufacturer that uses third-party testing for identity, contaminants and heavy metals. Avoid proprietary blends that hide the actual amount of ashwagandha.

Stay within doses used in clinical trials, generally 250–600 mg of extract per day, and limit continuous use to periods comparable to those studied, roughly two to three months, before reassessing with your doctor.

Learn the warning signs of liver injury: yellowing of the skin or eyes, dark urine, pale stools, persistent itching, unusual fatigue, nausea or pain in the upper right abdomen. If any appear, stop the supplement immediately and see a doctor, who can order liver function tests.

People who use ashwagandha long term may consider baseline and follow-up liver enzyme tests with their physician, especially if they take other supplements or medications.

Editorial team conclusions

For most healthy adults, short-term use of a quality ashwagandha extract appears to be well tolerated. However, liver injury, while rare, is documented and can be serious.

There is currently no reliable evidence that ashwagandha harms healthy kidneys, but data in people with kidney disease are lacking.

Recognizing the symptoms of liver trouble and stopping promptly is the most important safety measure for anyone who uses the herb.

Readers may also want to explore our editorial articles on liver enzyme tests for athletes, adaptogens and cortisol, and supplement-induced liver injury more broadly.

References

1. National Institute of Diabetes and Digestive and Kidney Diseases. Ashwagandha. In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Bethesda (MD): NIDDK; 2012–.
2. Björnsson HK, Björnsson ES, Avula B, et al. Ashwagandha-induced liver injury: a case series from Iceland and the US Drug-Induced Liver Injury Network. Liver Int. 2020;40(4):825–829.
3. Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian J Psychol Med. 2012;34(3):255–262.
4. Wankhede S, Langade D, Joshi K, Sinha SR, Bhattacharyya S. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. J Int Soc Sports Nutr. 2015;12:43.
5. Philips CA, Valsan A, Theruvath AH, et al. Ashwagandha-induced liver injury: a case series from India and literature review. Hepatol Commun. 2023.
6. Navarro VJ, Khan I, Björnsson E, et al. Liver injury from herbal and dietary supplements. Hepatology. 2017;65(1):363–373.