Ashwagandha
Also known as withania somnifera, ashwaganda, ashwagandha root, KSM-66.
Ashwagandha (Withania somnifera) is a botanical used in Ayurvedic practice and marketed for stress, sleep and exercise performance.
Last reviewed September 20, 2026 · Jump to references
Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.
Important cautions
Liver injury reportedhigh concern
Cases of hepatitis, sometimes with jaundice, have been reported weeks to months into use, and several national agencies have issued advisories. Stop and seek medical care for jaundice, dark urine, persistent nausea or abdominal pain.
Can alter thyroid hormone levelshigh concern
Raised thyroid hormones and cases of thyrotoxicosis have been reported. People with thyroid disease or on thyroid medicine should seek clinician advice and monitoring.
Avoid in pregnancy and breastfeedinghigh concern
Traditional use as an abortifacient and absence of safety data mean it should not be used in pregnancy, and it is not recommended while breastfeeding.
Autoimmune disease and immunosuppressantsmoderate concern
May stimulate immune activity, which could oppose immunosuppressant therapy or affect autoimmune conditions.
Additive sedationmoderate concern
Can add to the effects of sedatives, sleep medicines, opioids and alcohol.
Discuss with a clinician if any of these apply
- Pregnancy or breastfeeding
- Liver disease
- Thyroid disease
- Hormone-sensitive conditions
Evidence by use
Each use is rated on its own. There is no single overall effectiveness score.
Perceived stress and anxiety symptoms
PromisingSeveral small randomised trials report reduced stress scores over 6-12 weeks.
Trials are small, short, often industry-funded and use different extracts.
Populations studied: Adults with self-reported stress; not studied adequately in diagnosed anxiety disorders.
Sleep quality
Limited or mixedSome small trials report improved subjective sleep measures.
Strength and exercise performance
Limited or mixedSmall trials with inconsistent methods; not established.
Testosterone, fertility and thyroid function
Insufficient evidenceSmall studies exist; findings are preliminary and thyroid effects are a safety concern rather than a benefit.
Interactions to review
Thyroid hormone replacement
medication · high severity · limited evidence
Possible additive effect leading to excess thyroid hormone effects.
Benzodiazepines, z-drugs, opioids, alcohol
medication · moderate severity · limited evidence
Additive sedation.
Immunosuppressants
medication · moderate severity · limited evidence
Possible opposition to therapy through immune stimulation.
Antihypertensives and glucose-lowering drugs
medication · moderate severity · limited evidence
Possible additive lowering of blood pressure or glucose.
Liver disease
condition · high severity · moderate evidence
Existing liver disease increases concern given reported hepatotoxicity.
Thyroid function tests
laboratory · moderate severity · moderate evidence
May shift TSH and thyroid hormone results.
Surgery
procedure · moderate severity · limited evidence
Disclose use because of sedative and blood-pressure effects.
Complete Research Guide
Open each section for the available evidence. Gaps are stated rather than inferred.
Overview
Ashwagandha is a root extract promoted as an adaptogen for stress, sleep and performance. Short trials suggest it may reduce stress scores, but studies are small and the products differ. It is not a low-consequence herb: liver injury reports and thyroid hormone effects are documented.
Technical detail
Primary category: Herbs & Botanicals; goal tags: stress support, sleep support. Alternate names: Withania somnifera, Indian ginseng, winter cherry.
Section last reviewed Sep 20, 2026
Structure & Properties
Products are made from root or root-and-leaf extracts standardised to withanolides. Branded extracts used in trials differ in plant part, extraction method and withanolide content, so results from one do not automatically apply to another.
Technical detail
Withanolides are steroidal lactones. Leaf material contains a different withanolide profile than root and is restricted in some traditional preparations. Store dry and away from light and heat.
Section last reviewed Sep 20, 2026
How It Works
Proposed mechanisms involve modulation of the stress-hormone axis, GABAergic signalling and inflammatory markers. Human mechanistic evidence is limited.
Technical detail
Hypothesised HPA-axis modulation with reported reductions in cortisol in some small trials, GABA-mimetic activity in preclinical models, and antioxidant effects. Areas of uncertainty include which withanolides matter and whether cortisol change explains symptom scores.
Section last reviewed Sep 20, 2026
Human Research
Most trials enrol fewer than a hundred adults for 8-12 weeks and report improvements in stress or sleep questionnaires. Independent reviews describe the overall body of evidence as low to moderate quality with risk of bias and inconsistent outcome measures, and long-term data are absent.
Technical detail
Evidence assessed separately by outcome and extract: stress promising, sleep limited to mixed, performance and hormonal outcomes insufficient. Negative and null findings are under-represented in marketing materials.
Section last reviewed Sep 20, 2026
Laboratory Research
Animal and cell studies describe anti-inflammatory, antioxidant and anxiolytic-like effects and activity of individual withanolides.
Evidence gap: Non-human evidence. It generates hypotheses and does not establish human benefit or define safe long-term use.
Section last reviewed Sep 20, 2026
Processing & Interactions
Ashwagandha may add to the effects of sedatives, thyroid medicines, blood-pressure and diabetes medicines, and may stimulate immune activity, which matters for people taking immunosuppressants.
Technical detail
Additive sedation with benzodiazepines, z-drugs, opioids and alcohol. Possible additive effect with thyroid hormone replacement leading to excess thyroid effects. Possible additive hypotensive and glucose-lowering effects. Theoretical opposition to immunosuppressant therapy. Thyroid function tests may shift, complicating interpretation.
Section last reviewed Sep 20, 2026
Safety & Precautions
Reported effects include stomach upset, diarrhoea, drowsiness and headache. More serious concerns are liver injury — international case reports and national advisories describe hepatitis, sometimes with jaundice, occurring weeks to months into use — and changes in thyroid hormone levels, including cases of thyrotoxicosis. It should not be used in pregnancy, has traditional use as an abortifacient, and is not recommended while breastfeeding. People with autoimmune or thyroid disease, hormone-sensitive prostate cancer, liver disease, or taking sedatives or immunosuppressants should seek clinician advice. Stop and seek care for jaundice, dark urine, persistent nausea or abdominal pain.
Section last reviewed Sep 20, 2026
Administration & Studied Formulations
Standardised root extracts in capsules are the most studied form; powders, gummies and teas are not equivalent.
Technical detail
No dietary reference intake exists. Trials used specific branded extracts at protocol amounts for 8-12 weeks; those amounts are tied to those preparations and populations and are not personal recommendations. Long-term use has not been adequately studied.
Section last reviewed Sep 20, 2026
Applications & Related Therapies
For stress and sleep, better-supported approaches include cognitive behavioural therapy for insomnia, structured exercise, sleep scheduling, caffeine and alcohol review, and treatment of underlying anxiety or depression. Ashwagandha is an adjunct under study, not a treatment for a diagnosed disorder.
Section last reviewed Sep 20, 2026
Cases, Considerations & Ethics
Educational example: an adult takes a high-strength extract for three months, develops fatigue and yellowing of the eyes, and liver tests are abnormal with no other cause found. Decision factors are duration of use, product identity and strength, other liver-affecting medicines, and prompt recognition. Questions for a clinician or pharmacist: is this safe with my thyroid medicine, could it affect my liver, and how long should I take it? Marketing that presents adaptogens as consequence-free understates documented liver and thyroid events, and pregnancy warnings are often missing from labels.
Section last reviewed Sep 20, 2026
References
Third-party testing: Extracts are often standardised to withanolides; standardisation indicates a marker level, not clinical effect, and root versus root-and-leaf products differ.
- National Center for Complementary and Integrative HealthAshwagandhaAccessed September 20, 2026
- LiverTox (NIDDK / NLM)Ashwagandha — Clinical and Research Information on Drug-Induced Liver InjuryAccessed September 20, 2026