Evidence-backed FAQ
Can ashwagandha affect the thyroid?
Important limitations
Based on a single small pilot trial of 50 adults with subclinical hypothyroidism using 600 mg per day for 8 weeks; it does not establish symptom improvement, long-term benefit, or benefit in overt hypothyroidism and should not replace prescribed thyroid management. Discuss these conditions and any planned surgery with your healthcare professional before considering ashwagandha; supplement research does not justify changing prescribed care.[1], [2]
What the evidence shows
Based on a single small pilot trial of 50 adults with subclinical hypothyroidism using 600 mg per day for 8 weeks; it does not establish symptom improvement, long-term benefit, or benefit in overt hypothyroidism and should not replace prescribed thyroid management. Discuss these conditions and any planned surgery with your healthcare professional before considering ashwagandha; supplement research does not justify changing prescribed care.[1], [2]
What the cited evidence shows
In a small randomized, double-blind, placebo-controlled trial of adults with subclinical hypothyroidism, ashwagandha root extract significantly improved serum TSH, T3, and T4 levels compared with placebo. Based on a single small pilot trial of 50 adults with subclinical hypothyroidism using 600 mg per day for 8 weeks; it does not establish symptom improvement, long-term benefit, or benefit in overt hypothyroidism and should not replace prescribed thyroid management.[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.[2]
Safety belongs in the decision
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.[2]
Read the supporting evidence summaries
The linked research pages provide study populations, formulations, doses, outcomes, and limitations in greater detail.
Related questions
References
- Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients: A Double-Blind, Randomized Placebo-Controlled Trial.. Journal of alternative and complementary medicine (New York, N.Y.). 2018. Randomized controlled trial View source →
- Ashwagandha: Usefulness and Safety. NIH National Center for Complementary and Integrative Health. Retrieved 2026-09-30. Government health fact sheet View source →