What Is Ashwagandha?
Ashwagandha is Withania somnifera, an evergreen shrub whose root is sold as a standardized extract. NCCIH says some preparations may help with insomnia and stress, that evidence on anxiety is unclear, and that it should be avoided in pregnancy. ODS reports short-term use up to about three months and notes Denmark banned ashwagandha in food supplements in 2023.
Ashwagandha is the common name for Withania somnifera, an evergreen shrub found in parts of India, Africa, and the Middle East. NCCIH says it contains withanolides and that supplements typically use root, leaf, or root-and-leaf extracts. ODS adds that the Sanskrit name refers to the smell of the fresh root.
What is ashwagandha?
NCCIH describes ashwagandha as an evergreen shrub used for thousands of years, especially in Ayurvedic practice. ODS gives the binomial Withania somnifera (L.) Dunal and notes the species name somnifera comes from the Latin for sleep-inducing. Both agencies say commercial products are usually extracts, and ODS says root and leaf differ in chemical composition.
ODS also says ashwagandha is rich in steroidal lactones called withanolides, plus alkaloids. A label that states only “ashwagandha 600 mg” does not state which plant part or what withanolide standard was used.
What does NCCIH say the research shows?
NCCIH states that some ashwagandha preparations may be effective for insomnia and stress, and that evidence is unclear about effects on anxiety. It says there is some limited evidence that 2 to 4 months of use may increase testosterone levels and sperm quality. It says there is not enough evidence to determine whether ashwagandha is helpful for other listed conditions, including athletic performance, cognitive function, and menopause.
Those sentences are NCCIH’s summary. This page does not upgrade them.
How much ashwagandha appears in the studies ODS reviewed?
ODS describes trials that used extract doses from 240 to 1,250 mg a day, and one trial of 12,000 mg a day of whole-root granules. A 2021 sleep review it cites used 250 to 600 mg a day of a root extract, or 120 mg a day of a root-and-leaf extract, for 6 to 12 weeks. ODS says it is hard to name one extract or amount because preparations differ.
Those are study amounts, not a dose this site recommends.
What safety information is published?
NCCIH says ashwagandha may be safe in the short term, up to 3 months, and that long-term safety cannot be judged from the available information. Common effects it lists are drowsiness, stomach upset, diarrhea, and vomiting. It reports rare cases of liver injury linked to ashwagandha supplements.
NCCIH says ashwagandha should be avoided during pregnancy and should not be used while breastfeeding. It is not recommended for people about to have surgery, or for people with autoimmune or thyroid disorders. NCCIH also notes possible interactions with medicines for diabetes and high blood pressure, immunosuppressants, sedatives, anticonvulsants, and thyroid hormone medicines, and says people with hormone-sensitive prostate cancer should avoid it because ashwagandha may increase testosterone.
ODS agrees that short-term use up to about 3 months has been well tolerated in trials, that long-term safety is unknown, and that liver and thyroid signals have been reported. ODS records that Denmark banned ashwagandha in 2023 after a risk assessment that discussed possible effects on pregnancy and on thyroid and sex hormones.
This page does not interview experts and does not add a medical-review byline.
Sources
- Ashwagandha: Usefulness and Safety. National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/health/ashwagandha Accessed 2026-08-18.
- Ashwagandha: Is it helpful for stress, anxiety, or sleep? — Health Professional Fact Sheet. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Ashwagandha-HealthProfessional/ Accessed 2026-08-18.