Updated April 2026Evidence-Based

Ashwagandha: Benefits, Dosage and Side Effects

Also known as: Withania somnifera, Indian winter cherry, KSM-66

Illustration representing Ashwagandha, the ingredient this guide covers

Ashwagandha is an adaptogenic herb used in Ayurvedic medicine for over 3,000 years. Modern clinical trials show it helps the body manage cortisol, supports sleep quality, and modestly improves strength output. The most studied form is KSM-66, a standardised root extract.

Ashwagandha: products that state their dose

Research on ashwagandha generally uses 300 mg/day. These are the products we found that put an amount on the label, so you can check them against it. Sorted by whether they reach that figure, then by how many people have rated them.

Prices and ratings were recorded when this page was last updated and change often; the figure on Amazon is the one that counts. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. Nothing on this list is paid placement: it is ordered on stated dose and rating volume, and we earn the same on all of it.

How Ashwagandha Works

Ashwagandha works primarily by modulating the hypothalamic-pituitary-adrenal (HPA) axis. The withanolides (active compounds) bind to GABA receptors, reduce cortisol synthesis at the adrenal cortex, and dampen the body's stress response. Secondary mechanisms include thyroid hormone modulation and increased nitric oxide production.

Benefits

  • Stress & anxiety: Multiple double-blind RCTs show 25 to 30% reductions in self-reported stress vs placebo at 600 mg/day.
  • Sleep quality: Improves sleep onset latency and total sleep time in adults with insomnia.
  • Strength: Resistance-trained men taking 600 mg/day showed greater bench press and leg extension gains than placebo over 8 weeks.
  • Testosterone: Modest increases (10 to 14%) in serum testosterone in men with low baseline levels.

Research Summary

Over 80 published human trials, including ~25 RCTs. Evidence is strongest for stress/anxiety reduction (Lopresti 2019; Salve 2019) and sleep quality (Langade 2021). Strength evidence is moderate (Wankhede 2015). Testosterone evidence is preliminary and dose-dependent.

Recommended Dosage

Min effective dose

300 mg/day

Max safe dose

1,000 mg/day (short-term)

The standardised range is 300 to 600 mg/day of a root extract such as KSM-66 or Sensoril. Doses up to 1,000 mg/day have been studied for short periods (<12 weeks). Take with food to reduce GI upset.

Side Effects

Generally well tolerated. Possible: mild GI upset, drowsiness, lower blood pressure. Rare: liver enzyme elevations (case reports).

Interactions

May potentiate sedatives and thyroid medication. Caution with immunosuppressants, anti-diabetic drugs, and blood pressure medications. Avoid in pregnancy.

Best Supplements Containing Ashwagandha

Frequently Asked Questions

Medical Disclaimer

The content on this page is for informational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult your physician or qualified healthcare provider before starting any new supplement regimen. Individual results may vary.

Sources & References

  1. Lopresti AL et al. 2019. An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract. Medicine.
  2. Salve J et al. 2019. Adaptogenic and anxiolytic effects of ashwagandha root extract. Cureus.
  3. Wankhede S et al. 2015. Examining the effect of Withania somnifera supplementation on muscle strength. JISSN.