Research review
Does ashwagandha lower cortisol? What the research does and doesn't show
A 2025 meta-analysis of 7 randomized trials found ashwagandha significantly lowered measured cortisol, but found no significant effect on self-reported perceived stress across 6 trials. The biological marker and the subjective feeling didn't move together, and no trial tested plain root powder.
A 2025 meta-analysis of 7 randomized trials found ashwagandha significantly lowered measured cortisol compared with placebo. The same review found no significant effect on self-reported perceived stress across the trials that measured it. The lab number and how people said they felt didn't move together — a real, if incomplete, result worth stating plainly.
What the evidence doesn't support
It doesn't support ashwagandha as a guaranteed way to lower cortisol for any given person, and it doesn't support the idea that a lower cortisol reading means someone will feel less stressed — the largest pooled analysis found those two things didn't track together. It also doesn't support any specific timeline ("how quickly") or a dose calibrated to plain root powder, since no trial tested that form.
What the trials found
A 2025 systematic review and meta-analysis searched four databases for randomized trials running at least 2 weeks with oral ashwagandha doses of 250 mg/day or higher. Seven trials measuring cortisol and six measuring self-reported perceived stress, totaling 488 participants, qualified. Pooled, cortisol fell significantly versus placebo. Pooled, perceived stress did not change significantly versus placebo. The review's own title calls this a "dual impact" — cortisol down, subjective stress unchanged — and flags that longer trials and more diverse populations are still needed before drawing firmer conclusions.
A single, well-designed 2012 trial adds a case where the two measures did move together: 64 adults with a documented history of chronic stress took 600 mg/day of a concentrated root extract or placebo for 60 days. Both self-reported stress scores and serum cortisol fell significantly more in the treatment group. This is one of the stronger individual trials in the category — randomized, placebo-controlled, with matching results on both an objective and a subjective measure.
A 2022 trial complicates the dose picture further: 60 healthy adults were split between 225 mg/day of a root-and-leaf extract, 400 mg/day of the same extract, or placebo, for 30 days. Cortisol fell significantly at the lower 225 mg/day dose but not at the higher 400 mg/day dose — the opposite of what a simple dose-response relationship would predict. Self-reported stress, mood and anxiety improved equally across all three groups, including placebo.
Across the trials in the meta-analysis, doses ranged from 250 mg/day up to 600 mg/day of various extracts, for 30 to 90 days. None tested whole root powder, and no trial establishes how fast a cortisol change would appear on that form or how large it would be.
Questions people ask
Does ashwagandha lower cortisol?
Pooled across 7 randomized trials, yes, on average. Whether that translates to feeling less stressed is a separate question the same body of evidence answers no to — perceived stress didn't move with it.
How quickly does ashwagandha lower cortisol?
The trials measuring this ran 30 to 90 days, with the significant result reported at the end of that window. None measured cortisol at earlier timepoints in a way that would support a claim about days or weeks.
How much ashwagandha to lower cortisol?
The pooled trials used 250 mg/day or more of various extracts. One trial found 225 mg/day worked and 400 mg/day of the same extract didn't, so there's no clean dose-response relationship to point to, and no data at all for root powder.
Does ashwagandha calm you down?
"Calm" isn't a measure any trial used. The closest available measures — self-reported stress and mood scores — mostly didn't differ from placebo, even in trials where cortisol did.
When to talk to a doctor
Cortisol levels are best interpreted by a doctor alongside symptoms and, if needed, blood or saliva testing — a supplement isn't a way to self-diagnose or manage a cortisol problem. If persistent stress is affecting sleep, mood or daily function, that's worth raising directly with a doctor. If you take a sedative, thyroid medication, or a corticosteroid, talk to a doctor before adding any supplement.
Related reading: ashwagandha and stress, ashwagandha and testosterone, and ashwagandha and your thyroid.
Sources
- Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress - A systematic review and meta-analysis A 2025 meta-analysis of 7 trials (488 participants) found ashwagandha significantly lowered cortisol versus placebo, but a matched analysis of 6 trials found no significant effect on self-reported perceived stress.
- A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults In a 60-day trial, 600 mg/day of a concentrated ashwagandha extract lowered stress-scale scores and cortisol more than placebo in adults with chronic stress.
- Efficacy of Withania somnifera supplementation on adult's cognition and mood In 60 healthy adults with perceived stress, a root-and-leaf extract at 225-400 mg/day for 30 days improved some cognitive test scores and lowered cortisol at the lower dose, but self-reported stress and mood improved equally with placebo.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.