Does ashwagandha lower cortisol? (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.