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ingestible · for thyroid support

Ashwagandha (Withania somnifera)

Reviewed by the Nimbera editorial team · Last updated May 2026

A double-blind RCT (n=50; J Altern Complement Med 2018, PMID 28829155) found 600 mg/day ashwagandha root extract for 8 weeks significantly improved TSH (p < 0.001), T3 (p=0.003), and T4 (p=0.01) vs. placebo in subclinical hypothyroid patients. Evidence is limited to a single small trial - larger replication is needed.$20-$40 per month.

How to use

Take 300-600 mg of ashwagandha root extract (standardized to 5% withanolides) daily with food. KSM-66 and Sensoril are clinically studied branded extracts. Use for no more than 3 months at a time without reassessing thyroid labs.

How it works

Ashwagandha is an adaptogenic herb that reduces cortisol. Chronic stress elevates cortisol, which impairs the conversion of T4 to active T3 and may suppress thyroid-stimulating hormone (TSH) signaling. By reducing the HPA axis response, ashwagandha may support thyroid hormone production and conversion indirectly.

Where to buy

Health food stores and online. Look for KSM-66 or Sensoril branded extracts with standardized withanolide content. Third-party tested products preferred.

Typical cost: $20-$40 per month.

Safety notes

CAUTION: Ashwagandha may further lower TSH and raise thyroid hormone levels - do not use if you have hyperthyroidism or Graves' disease. May interact with thyroid hormone replacement medications (levothyroxine) by altering drug levels; inform your doctor and monitor TSH closely if combining. Not safe during pregnancy (may induce miscarriage). Rarely associated with liver injury - discontinue and seek medical attention if jaundice or abdominal pain develops. This remedy is based on a single small trial; it is not a substitute for prescribed thyroid treatment.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Sharma et al. J Altern Complement Med 2018 - PMID 28829155

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.