In a nutshell
- In studies, ashwagandha slightly reduced stress and anxiety and slightly improved sleep — but the evidence is still weak.1,2
- Rarely, it damages the liver, and it may affect the thyroid; Denmark has banned it in supplements.4,5,7
- Pregnant and breastfeeding women, children and people with thyroid, liver or heart disease should not take it.6
1What it is
Ashwagandha (Withania somnifera) is a shrub whose root is used in Indian Ayurveda. Supplements contain root powder or extract, usually at doses of around 300–600 mg a day — the doses tested in the studies below.1,2
2Stress and anxiety
Moderate evidence
12 studies, 1,002 people
A summary of randomised placebo-controlled trials: people taking ashwagandha reported less stress and anxiety. A dose
of around 600 mg a day came out best. The authors, however, rate the certainty of the evidence as low — the studies
were small and short.1
3Sleep
Moderate evidence
5 studies, 400 people
Ashwagandha had a small but significant effect on sleep. It was more pronounced in people with insomnia, at a dose of
at least 600 mg a day and after at least 8 weeks of use.2
4Strength and muscles
Weak evidence — one small study
57 men started strength training; half took 600 mg of extract for 8 weeks, half a placebo. The ashwagandha group added
more to their bench press (46 kg vs 26 kg). This is a single small study with a commercial extract — not enough to be
sure.3
5Safety: what to watch out for
Confirmed cases
Rarely, ashwagandha damages the liver. The US LiverTox database considers it a probable cause of such cases; most were
mild and resolved, but deaths have also been reported.4 Doctors in India described 23
cases — three people who already had liver disease died.5
Authorities
In 2024 the French food safety agency ANSES advised that it should not be taken by pregnant and breastfeeding women,
children and people with thyroid, liver or heart disease — especially if they take medication.6
Denmark has banned ashwagandha in food supplements because of possible effects on thyroid and sex hormones.7
What to take from this
- If you try ashwagandha, tell your doctor — especially if you take medication or have thyroid or liver problems.
- If your skin or eyes turn yellow, your urine gets dark or you start to itch, stop it right away and see a doctor.4
- Not during pregnancy or breastfeeding.
Sources
Written on , based on studies available at that date. Newer research may change the conclusions.
- Akhgarjand C. et al. (2022). Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials. Phytotherapy Research 36(11):4115–4124. doi.org/10.1002/ptr.7598
- Cheah K. L. et al. (2021). Effect of Ashwagandha (Withania somnifera) extract on sleep: a systematic review and meta-analysis. PLoS ONE 16(9):e0257843. doi.org/10.1371/journal.pone.0257843
- Wankhede S. et al. (2015). Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. JISSN 12:43. doi.org/10.1186/s12970-015-0104-9
- LiverTox: Clinical and Research Information on Drug-Induced Liver Injury — Ashwagandha. National Institute of Diabetes and Digestive and Kidney Diseases (NIH). ncbi.nlm.nih.gov/books/NBK548536
- Philips C. A. et al. (2023). Ashwagandha-induced liver injury — A case series from India and literature review. Hepatology Communications 7(10):e0270. pubmed.ncbi.nlm.nih.gov/37756041
- NutraIngredients (17 June 2024). French agency warns ashwagandha unsafe in specific populations — on the ANSES opinion. nutraingredients.com
- NutraIngredients (30 May 2023). Experts defend ashwagandha amid safety concerns — on the Danish ban and the DTU assessment. nutraingredients.com
This is general information and does not replace a doctor. Food supplements are not medicines, and their composition varies between manufacturers.