Ashwagandha (KSM-66)

Some small trials have looked at ashwagandha root extract in people with subclinical hypothyroidism and reported changes in thyroid hormone levels, but the research is limited and short-term, and it does not show that ashwagandha treats thyroid disease. Because it may raise thyroid hormone levels, it can interfere with thyroid medicines and is not appropriate for everyone, including people with hyperthyroidism.

People with thyroid conditions should not self-treat with supplements and should ask their endocrinologist or doctor first. Whether it suits you depends on your health, medicines and test results — ask a clinician.

Trials have used roughly 300–600 mg of root extract daily. This is not a recommendation. Anyone with a thyroid condition should ask their doctor before use. Doses vary by product and person; this is not personal medical advice.

Studies measured thyroid markers after about 8 weeks. Results vary.

Stomach upset and drowsiness are reported. Rare cases of liver injury and of thyroid over-activity have been reported.

Avoid during pregnancy. Do not use if you have hyperthyroidism. Ask your doctor before using it with thyroid medicine. Many clinicians advise stopping about 2 weeks before surgery.

Evidence level (our editorial summary, not a formal grading): Limited.

Pregnancy & breastfeeding: Avoid during pregnancy and breastfeeding.

Medication interactions: May interact with levothyroxine and other thyroid medicines, sedatives, immunosuppressants, and diabetes or blood-pressure medicines.

Talk to a healthcare professional before use if you are pregnant, breastfeeding, planning pregnancy, have a medical condition, take any medicine, or are scheduled for surgery. Dietary supplements are not approved by the FDA for safety or effectiveness before they are sold, and quality varies between products.

Reliable sources to check: NIH Office of Dietary Supplements fact sheets · NCCIH Herbs at a Glance · MedlinePlus Herbs & Supplements · FDA — Dietary Supplements