Research summary
Ashwagandha Safety and Tolerability
Short-term tolerability findings do not establish that ashwagandha is safe for every person. Reported concerns include drowsiness, gastrointestinal symptoms, rare liver injury reports, and possible medication interactions. Pregnancy, breastfeeding, thyroid or autoimmune disorders, planned surgery, and hormone-sensitive prostate cancer require particular caution.[1]
Who should avoid use or seek individual advice
NCCIH advises avoiding ashwagandha during pregnancy and not using it while breastfeeding. Short-term studies in other adults do not establish safety during pregnancy or breastfeeding; discuss any exposure or supplement plans with a qualified healthcare professional.[1]
NCCIH does not recommend ashwagandha for people with thyroid or autoimmune disorders or those who are about to have surgery. Discuss these conditions and any planned surgery with your healthcare professional before considering ashwagandha; supplement research does not justify changing prescribed care.[1]
NCCIH advises people with hormone-sensitive prostate cancer to avoid ashwagandha because it may increase testosterone. This is a condition-specific safety caution, not a treatment recommendation or an instruction to change cancer care.[1]
Ashwagandha may interact with medicines for diabetes or high blood pressure, immunosuppressants, sedatives, anticonvulsants, and thyroid hormone medicines. Discuss possible interactions with your prescriber or pharmacist before use; do not stop, replace, or adjust prescribed medicines based on supplement information.[1]
What ashwagandha is
Ashwagandha (Withania somnifera) is an evergreen shrub used in traditional Ayurvedic medicine. Supplements may contain extracts of its root, leaf, or both.[1]
What short trials can establish
In one randomized, placebo-controlled trial of 80 healthy adults, ashwagandha root extract at 300 mg twice daily was generally well tolerated over eight weeks, with no statistically significant abnormalities reported in the assessed blood, liver, or thyroid tests. These findings concern one short trial in selected healthy adults; they do not establish long-term or high-dose safety or rule out rare harms, and they are not a substitute for individual medical advice.[2]
NIH guidance describes short-term tolerability observations for ashwagandha over about three months, while safety over longer periods remains unknown. Short studies cannot establish safety for every person, preparation, or duration of use.[1]
Reported side effects and liver injury
Ashwagandha can cause drowsiness and gastrointestinal symptoms, including stomach upset, diarrhea, and vomiting. These reported effects do not describe every possible adverse reaction or predict an individual response.[1]
Rare reports have linked ashwagandha supplements with liver injury. Short-term tolerability findings do not rule out rare harms or establish long-term safety.[1]
References
- Ashwagandha: Usefulness and Safety. NIH National Center for Complementary and Integrative Health. Retrieved 2026-09-30. Government health fact sheet View source →
- Safety of Ashwagandha Root Extract: A Randomized, Placebo-Controlled, study in Healthy Volunteers.. Complementary therapies in medicine. 2021. Randomized controlled trial View source →
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