Ashwagandha (Withania somnifera) is an evergreen shrub whose root has been used in Ayurvedic medicine. As a supplement, usually a root or root-and-leaf extract, it is mostly used for stress, anxiety and sleep.
Also known as: Withania somnifera, KSM-66, Indian ginseng.
Ashwagandha has no intake value or upper limit. ODS says a 2021 review of sleep trials used 250 to 600 mg a day of root extract (KSM-66), or 120 mg a day of a root and leaf extract, and that a 2022 international taskforce provisionally recommended 300 to 600 mg a day of root extract standardized to 5% withanolides for generalized anxiety disorder. These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. Denmark banned ashwagandha in 2023, and France's food safety agency recommended against it for some groups in 2024 (ODS).
ODS says several small, short trials found ashwagandha may lower perceived stress and anxiety and improve sleep, but studies used different extracts and doses, so specific amounts are hard to recommend. It appears well tolerated for up to about 3 months; long-term safety is unknown. Common side effects are stomach upset, loose stools, nausea and drowsiness. ODS lists cases of liver injury, effects on thyroid hormone levels (including cases of thyrotoxicosis), and possible interactions with thyroid, diabetes, blood pressure, immunosuppressant and sedative medicines. Some experts advise against it in pregnancy and in men with hormone-sensitive prostate cancer.
We could not find a single published half-life or time to peak for ashwagandha that applies to a supplement dose, so we do not list one. Extracts contain many compounds (withanolides and alkaloids) in amounts that differ by product.
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