Does ashwagandha lower cortisol? Evidence review (2026)

Ashwagandha is the most-studied cortisol-lowering supplement. Here's what the meta-analyses actually show, plus dose and timing.

Updated May 23, 2026 · Reviewed by Cortisol+ Editorial

Verdict

Yes, ashwagandha lowers cortisol — with moderate-to-strong evidence in adults under chronic stress. Multiple randomized trials show 15–30% reductions in morning serum cortisol over 8 weeks.

The studies

The evidence base is unusually robust for an herbal supplement. Key trials:

  • Salve et al. 2019 (60 chronically stressed adults, KSM-66 300 mg twice daily, 8 weeks): 27.9% reduction in serum cortisol vs 7.9% in placebo. Significant improvements in perceived stress and sleep quality.
  • Chandrasekhar et al. 2012 (64 chronically stressed adults, KSM-66 300 mg twice daily, 60 days): 27.9% serum cortisol reduction vs 7.9% placebo. Significant reduction in the Perceived Stress Scale.
  • Lopresti et al. 2019 (60 stressed adults, Shoden 240 mg once daily, 60 days): 23% morning cortisol reduction.
  • Multiple meta-analyses (2021–2023) consistently confirm a 15–30% reduction in morning cortisol across studies. Effect size is larger in populations with elevated baseline stress.

Most positive trials use 300–600 mg/day of standardized extract for 8–12 weeks. Lower doses (125–250 mg) show smaller effects; doses above 600 mg/day don’t appear to add benefit. Time-to-effect is typically 4 weeks for subjective stress, 8 weeks for cortisol biomarkers.

How to use

  • Form: KSM-66 (full-spectrum root extract, withanolides standardized to 5%) has the largest evidence base. Sensoril is a leaf+root extract with slightly different effect profile (more sedating). Generic “ashwagandha root powder” without standardization has weaker evidence.
  • Dose: 300–600 mg/day. Many practitioners split into 300 mg morning + 300 mg evening for steadier effect.
  • Timing: Adaptogenic, not strictly stimulating or sedating. Evening dose may best target evening cortisol elevation. Some users find it mildly relaxing — taking it 2–3 hours before bed is a common protocol.
  • Duration: Most trials run 8 weeks. Cycle off after 12 weeks for 2–4 weeks before restarting.
  • Avoid if: Pregnant, breastfeeding, autoimmune condition (it’s immunostimulating), on thyroid medication (can affect thyroid function), on sedatives or anti-anxiety meds. Talk to a doctor before combining with prescription medications.
  • Side effects: Generally well-tolerated. Most common: mild GI upset, occasional drowsiness. Rare: thyroid stimulation requiring dose adjustment in patients with thyroid disease.

How Cortisol+ tracks this

If you start ashwagandha, Cortisol+ surfaces the change in your HRV-based cortisol score over the following weeks — so you can see if it’s actually working for you.

Frequently asked questions

Does ashwagandha lower cortisol? +
Ashwagandha is the most-studied cortisol-lowering supplement. Here's what the meta-analyses actually show, plus dose and timing.
What dose of ashwagandha lowers cortisol? +
Most positive trials use 300–600 mg/day of a standardized root extract (KSM-66 or Sensoril), taken consistently for 8–12 weeks. Lower doses (125–250 mg) show smaller effects; doses above 600 mg/day don't appear to add benefit. Time-to-effect is typically 4–8 weeks.
When should I take ashwagandha — morning or night? +
Ashwagandha is adaptogenic, not sedating, so timing matters less than consistency. Some users prefer evening dosing because of mild relaxation effects; others split the dose (morning + evening). For cortisol specifically, taking it 2–3 hours before bed may best target evening cortisol elevation.
How does ashwagandha compare to rhodiola for cortisol? +
Ashwagandha has stronger evidence for chronic cortisol reduction; rhodiola has better evidence for acute fatigue and mental performance under stress. They're often stacked. If your goal is lowering baseline cortisol, ashwagandha is the better-supported choice.
Who shouldn't take ashwagandha? +
Avoid during pregnancy, with thyroid medication (it can affect thyroid function), with sedatives, and if you have autoimmune conditions (it stimulates immune activity). Talk to a doctor before combining with prescription medications.
Will Cortisol+ show if ashwagandha is working for me? +
Yes — Cortisol+ tracks your HRV-based cortisol estimate continuously. Most users see a measurable trend change within 4–6 weeks of starting ashwagandha. Because individual response varies, biometric tracking is the only way to know if it's working for you specifically.