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In this article
Key points at a glance
- In ashwagandha studies, cortisol levels were mostly lower with the extract than with a placebo. For stress as participants rated it themselves, the picture is less consistent1,2.
- A meta-analysis of seven studies found cortisol levels 1.16 µg/dl lower on average, but no statistically significant difference on the questionnaire measuring perceived stress2.
- Most of the studies are small and short, and there’s hardly any data covering more than six months2,3.
- There’s no authorised health claim for ashwagandha in the UK or the EU.
What is ashwagandha, and why the focus on cortisol?
Ashwagandha (botanical name Withania somnifera) is a plant of the nightshade family and is widely used in traditional Ayurvedic medicine1,2. Standardised extracts made from the root are the form most commonly used3. You’ll find more about the plant itself in our article on the ashwagandha root.
Cortisol is a hormone that studies use as a biological marker of stress2. It’s measured in the blood, for example4. Alongside this, the studies use questionnaires in which participants rate their own stress. The two approaches answer different questions, and they don’t always lead to the same result2.
What did individual studies measure?
A randomised, double-blind study from 2012 included 64 adults who had been under stress for a long time (chronic stress)4. For 60 days, they took one capsule containing 300 mg of root extract twice daily, or a placebo. The researchers measured cortisol in the blood and recorded the results of several stress questionnaires4.
In this study, after 60 days, the scores on all the stress questionnaires were statistically significantly lower in the ashwagandha group than in the placebo group, and blood cortisol was markedly lower too4. Side effects were mild and similar in both groups. The extract was supplied by its manufacturer4.
A study from 2019 looked at 60 healthy adults who rated themselves as highly stressed. For 60 days, they took 240 mg of a different standardised extract once daily, or a placebo5. Morning cortisol fell more with ashwagandha than with the placebo5.
The questionnaire results were mixed. An anxiety scale rated by the investigators came out more favourably with ashwagandha. On a questionnaire about mood and stress that participants filled in themselves, the difference wasn’t statistically significant5. This study was funded by the manufacturer of the extract5.
What do the reviews say?
A review from 2023 screened 4,788 publications, and only nine studies met its criteria1. They differed in design, extract, dose and duration, which ranged from 30 to 112 days. Taken together, cortisol was lower with ashwagandha, without any notable side effects1.
9 of 4,788
publications met the criteria of one review on cortisol1
1.16 µg/dl
lower cortisol on average across seven studies, with no significant difference in perceived stress2
A meta-analysis from 2025 pooled the results of seven studies on cortisol and six studies on perceived stress, with 488 participants in total2. It found a significant difference for cortisol, but not for the stress questionnaire. The authors rated the risk of bias in the studies as mostly moderate2.
The gap between the measured value and how people actually feel is an important finding. A lower cortisol level doesn’t automatically mean that someone feels less stressed. Our article on how to read the evidence from studies explains how to make sense of differences like this.
How well did people tolerate ashwagandha in the studies?
A review from 2026 assessed 23 randomised studies involving a total of 2,317 healthy adults, all testing standardised root extracts3. Amounts ranged from 125 to 600 mg per day, and the duration from a single dose to 180 days. Liver, kidney and blood values stayed within the normal range, and no serious side effects caused by the extract were reported3.
Mild side effects such as an upset stomach, headaches or passing drowsiness were rarely reported, and occurred in both the extract and the placebo groups3. According to the authors, the safety concerns raised in individual case reports mainly involved non-standardised preparations or products combining several ingredients. Several of the authors have links to companies in the industry, and data beyond 180 days are scarce3.
Good to know None of the nine cortisol studies looked at long-term effects, so the authors of this review recommend taking ashwagandha under medical supervision1. If you take any medicines, check with your doctor first. Do not exceed the recommended daily amount.
How to weigh up the evidence
Ashwagandha studies fairly consistently find lower cortisol levels than with a placebo1,2,3. For perceived stress the picture is less clear, and most of the studies are small and short.
If you’d like to read about timing, our article Morning or evening? When to take supplements, from ashwagandha to turmeric looks at it in detail. At Melinava, we use phospholipids from European sunflowers for our liposomal products.
Frequently asked questions about ashwagandha and cortisol
Has ashwagandha been studied in humans?
Yes. A 2026 review found 23 randomised studies in healthy adults that tested standardised root extracts3. On cortisol specifically, nine studies met the criteria of another review1.
What does the ashwagandha study on cortisol show?
In the 2012 study with 64 adults, cortisol was markedly lower after 60 days than with the placebo4. Across seven studies, the difference in cortisol averaged 1.16 µg/dl2.
What is the evidence on the effects of ashwagandha?
The studies report measured values and questionnaire results. There’s no authorised health claim for ashwagandha in the UK or the EU. For cortisol the results are fairly consistent; for perceived stress they aren’t. The authors of the reviews would like to see longer and larger studies2,3.
Sources
- Della Porta M, Maier JA, Cazzola R (2023). Effects of Withania somnifera on Cortisol Levels in Stressed Human Subjects: A Systematic Review. Nutrients 15(24):5015. DOI
- Albalawi AA (2025). Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress. A systematic review and meta-analysis. Nutrition and Health 31(4):1395-1408. DOI
- Coope OC, Willems MET, Levington A, Tallon MJ, Roman-Viñas B, Spurr TJ (2026). Back to the Roots: Safety and Tolerability of Standardised Ashwagandha (Withania somnifera) Root Extract in Healthy Adults. A Systematic Review of Biomarkers and Adverse Events. Pharmaceuticals 19(5):725. DOI
- Chandrasekhar K, Kapoor J, Anishetty S (2012). 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. Indian Journal of Psychological Medicine 34(3):255-262. DOI
- Lopresti AL, Smith SJ, Malvi H, Kodgule R (2019). An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study. Medicine 98(37):e17186. DOI
This article is for general information only and should not replace medical advice. Food supplements are not a substitute for a balanced and varied diet and a healthy lifestyle.
Written by
Melinava Editorial Team