Is Ashwagandha Safe with Levothyroxine?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Monitor thyroid function tests (TSH, T3, T4) every 6-8 weeks if combining. Report symptoms of hyperthyroidism such as palpitations, tremor, heat intolerance, or weight loss to your provider immediately. Do not self-adjust levothyroxine dose.
Why this interaction occurs
Ashwagandha (Withania somnifera) has demonstrated thyroid-stimulating properties in clinical studies, increasing serum T3 and T4 levels. Co-administration with levothyroxine may produce additive or synergistic thyroid hormone elevation, increasing risk of iatrogenic hyperthyroidism, cardiac arrhythmias, and bone loss.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 302,514 reports mentioning Levothyroxine. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Levothyroxine + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Ashwagandha interactions → · All Levothyroxine interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.