Ashwagandha lowers cortisol. Feeling better is a separate question
Ashwagandha lowers cortisol. Feeling better is a separate question
Ashwagandha (Withania somnifera) is an Ayurvedic root now sold widely in Australia as a stress supplement. The headline claim, that it lowers cortisol, is unusually well supported for a supplement trend. Pooled analyses of randomised placebo-controlled trials repeatedly find lower circulating cortisol in the treated group.[2][4]
What that number means is a harder question. Cortisol is one output of the hypothalamic–pituitary–adrenal axis, read at a single moment. A 2025 meta-analysis of the same trial literature found the cortisol reduction was statistically clear while the change in perceived stress scores was not.[3] The biochemistry moved further than the experience did.
Duration is the other limit. Most trials run eight weeks or less, and the 2026 athlete study behind the recent coverage ran 42 days.[1] Nothing published tells us what a stress axis does after a year of daily use, and the axis adapts to what it is given.
There is also a safety signal that rarely reaches the label. Case series from Iceland, the United States and India describe cholestatic liver injury weeks into use, worst in people who already had liver disease.[13][14] For most people that is a reason to use it deliberately, for a defined period, rather than adding it to a shelf indefinitely.
What the trials actually measured
The study that drove most of the recent attention followed 56 rugby, water polo and football players through 42 days of pre-season training.[1] The popular version of that result is wrong. Salivary cortisol did not fall in the treated athletes. It rose in the placebo group and held steady in the treated group. Male athletes showed the same pattern in salivary cortisone. Pre-season loading pushes the stress axis up, and the supplement appeared to blunt that climb rather than push a resting level down.
Alongside that sit the pooled analyses. A 2024 review of nine randomised trials in 558 people reported reductions in perceived stress, anxiety ratings and serum cortisol against placebo.[2] A 2026 hormonal meta-analysis of 23 trials in 1,706 participants found a large pooled cortisol reduction, with a possible dose relationship tied to withanolide content.[4] Individual trials point the same way. A 60-day study in stressed adults found lower morning cortisol and lower DHEA-S.[5] An eight-week trial reported lower serum cortisol alongside fewer food cravings.[6] A 2026 trial in people with stress, anxiety and existing hypertension found much the same.[9] By supplement standards, that is a strong and repeatable signal.
Why a lower reading and a calmer week are different results
A 2025 meta-analysis separated the two outcomes and reported them side by side. Across seven trials measuring cortisol and six measuring the Perceived Stress Scale in 488 participants, cortisol fell by a clear and statistically significant margin, while the change in perceived stress did not reach significance.[3] The second half of that finding rarely makes it into the short version.
It is not a contradiction. Cortisol is a reading taken downstream of many inputs. The Perceived Stress Scale measures appraisal, which is how manageable your life feels to you. Two people can carry identical cortisol profiles into a clinic room and describe completely different weeks. Lowering a hormone does not remove a deadline, a night-waking toddler or a job that has outgrown the hours available.
Samples are small, heterogeneity between studies is moderate to high, and much of the research is funded by manufacturers testing their own extracts.[7][8] That is normal in supplement science, and it shapes which questions get asked.
What the research supports, outcome by outcome
Not every claim made for ashwagandha rests on the same quality of evidence.
| Outcome | What trials show | Consistency |
|---|---|---|
| Circulating cortisol | Lower than placebo across multiple pooled analyses | Strongest and most repeated finding |
| Sleep quality | Improved, most clearly in people diagnosed with insomnia and at longer trial durations | Reasonably consistent |
| Anxiety symptoms | Reduced on clinician-rated anxiety scales | Reasonably consistent, with high heterogeneity |
| Perceived stress | Improves in some pooled analyses and not in others | Mixed |
| Thyroid hormones | Modest rise in T4, with TSH and T3 unchanged | Small but repeated |
The cortisol number was never the whole diagnosis
Most people who ask about ashwagandha arrive with a frame already attached to it, usually some version of adrenal fatigue. A systematic review of 58 studies examined that idea directly and found no substantiation for it as a medical condition, with the cortisol tests used to diagnose it producing conflicting results.[18] Pushing a cortisol value down works on a marker that was never a diagnosis.
That does not make the exhaustion imaginary. It relocates the question. In clinic the useful work is finding what is generating the load: broken sleep, undereating relative to output, low iron, an unrecognised thyroid pattern, alcohol, or a genuine and unrelenting stressor that no capsule was going to resolve. We wrote about this in more detail in adrenal fatigue and the modern stress pattern.
Where cortisol is worth measuring, timing matters more than the single figure. A profile across the day, including the response after waking, shows the shape of the rhythm. That is what the DUTCH adrenal test is built for, and it answers a different question from a one-off morning blood result.
The safety signal that rarely reaches the label
Ashwagandha has a good general safety record in trials, with adverse events typically mild.[19] The concern sits outside the trials, in case reports. Five cases from Iceland and the United States Drug-Induced Liver Injury Network described jaundice, nausea and severe itch beginning two to twelve weeks after starting, with liver tests normalising one to five months after stopping.[13]
An Indian series reported eight cases from single-ingredient preparations. Three patients with pre-existing chronic liver disease developed liver failure and died. Chemical analysis of the retrieved products found no adulterant and no contaminant, which points at the herb itself.[14] A 2026 scoping review pooled 13 publications covering 25 patients across several regions and described a reproducible pattern: cholestatic or mixed injury, weeks of latency, usually self-limiting on stopping, with one transplant and three deaths at the severe end.[15]
Preclinical testing did not predict any of this, which is part of why it went unnoticed for so long.[17] Anyone with known liver disease should avoid it, and new jaundice or persistent itch warrants liver function testing, not a wait-and-see.
Thyroid, pregnancy and the people who should leave it alone
The 2026 hormonal meta-analysis found T4 rose modestly on ashwagandha while TSH and T3 were unchanged.[4] A small safety substudy inside a bipolar disorder trial saw the same direction, with T4 increasing in every treated participant and falling in most placebo participants.[16] For someone stable on thyroxine, or with Graves' disease, that is a live interaction rather than a theoretical one.
Pregnancy and breastfeeding are a straightforward avoid. The traditional reputation for inducing miscarriage was not reproduced in animal work, but no signal in preclinical models is not a safety clearance in humans.[17] Ashwagandha also has documented immunomodulating activity, so it deserves caution alongside immunosuppressant medication.[20]
Sedative interaction is the one people miss. If it is working on sleep, it is doing something to sedation, and stacking it with other sleep agents can be more than intended.[11]
How we approach it in clinic
Testing comes before treating. Before anything is added for stress or fatigue, we want thyroid function read properly, plus iron and ferritin, active B12, inflammatory markers and blood sugar. Those explain much of what gets labelled a cortisol problem.
When ashwagandha is used, it is a defined trial with a stated reason and a date to stop, alongside the work of reducing whatever is generating the load. That framing matters more than the product. For the broader picture, see our pages on hormones and stress and chronic fatigue and burnout, or read more about functional testing.
Key Insights
Frequently Asked Questions
Does ashwagandha actually lower cortisol?
Yes, and it is one of the more reliable findings in supplement research. Several independent meta-analyses of randomised placebo-controlled trials report lower circulating cortisol in treated groups, with the size of the effect appearing to track withanolide content. The caveats are that most trials are small, run eight weeks or less, and many are funded by the manufacturer of the extract being tested.
If my cortisol drops, will I feel less stressed?
Not necessarily. A 2025 meta-analysis looked at both outcomes across the same body of trials and found a clear reduction in cortisol alongside no significant change in perceived stress scores. Cortisol is an output of a system with many inputs, while perceived stress measures how manageable your circumstances feel. Lowering the hormone does not change the circumstances, and for many people the circumstances are the problem.
How long is it safe to take ashwagandha?
Honestly, nobody knows. Almost every published trial runs eight weeks or less, so continuous use beyond a few months sits outside the evidence entirely. Reported liver injury has typically appeared after weeks of use, and the stress axis adapts to sustained input, so a defined period with a review date makes more sense than open-ended daily use. Liver function testing is a reasonable precaution if you do continue.
Can I take ashwagandha if I am on thyroid medication?
Speak to whoever manages your prescription first. Pooled trial data show a modest rise in thyroxine on ashwagandha while TSH and T3 stay unchanged, and a small safety substudy pointed the same way. For someone whose thyroid dose has been carefully titrated, or anyone with Graves' disease, that warrants a conversation and possibly repeat thyroid testing rather than starting it quietly.
Who should avoid ashwagandha altogether?
Anyone with known liver disease, given the reported deaths in people with pre-existing cirrhosis. Pregnancy and breastfeeding, where human safety has not been established. People taking immunosuppressant medication, given documented immunomodulating activity. Caution is also reasonable alongside sedatives or other sleep agents. If jaundice, dark urine or persistent itch develop while taking it, stop and arrange liver function testing.
Ready to find answers?
If you are exhausted and reaching for a supplement to fix it, the more useful step is finding what is driving the load. That starts with proper testing and a clear read of your history.
References
- Coope OC, Otaegui E, Suárez M, et al. Ashwagandha root extract stabilises physiological stress responses in male and female team sports athletes during pre-season training. Nutrients. 2026;18(2):230. doi:10.3390/nu18020230
- Arumugam V, Vijayakumar V, Balakrishnan A, et al. Effects of ashwagandha (Withania somnifera) on stress and anxiety: a systematic review and meta-analysis. Explore (NY). 2024;20(6):103062. doi:10.1016/j.explore.2024.103062
- Albalawi AA. Dual impact of ashwagandha: significant cortisol reduction but no effects on perceived stress. A systematic review and meta-analysis. Nutr Health. 2025;31(4):1395–1408. doi:10.1177/02601060251363647
- Fornalik M, Malkiewicz A, Adamczak D, et al. Hormonal modulation with Withania somnifera: systematic review and meta-analysis of randomised controlled trials. Planta Med. 2026;92(8):790–805. doi:10.1055/a-2802-8363
- Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore). 2019;98(37):e17186. doi:10.1097/MD.0000000000017186
- Choudhary D, Bhattacharyya S, Joshi K. Body weight management in adults under chronic stress through treatment with ashwagandha root extract: a double-blind, randomized, placebo-controlled trial. J Evid Based Complementary Altern Med. 2017;22(1):96–106. doi:10.1177/2156587216641830
- Thanawala S, Shah R, Alluri KV, et al. Efficacy and safety of ashwagandha root extract sustained-release capsules in healthy adult, stressed subjects: a randomized, double-blind, placebo-controlled, parallel-group, 3-arm clinical trial. Medicine (Baltimore). 2026;105(11):e47990. doi:10.1097/MD.0000000000047990
- West RE, Biswas A, Rao R, Tayade H, Ademola J. A proprietary herbal extract of ashwagandha root for stress and anxiety in healthy adults: a randomized, double-blind, three-arm, placebo-controlled efficacy and safety study. J Med Life. 2026;19(1):49–62. doi:10.25122/jml-2025-0172
- Pattojoshi A, Kumar Patra S, Idrees SA, et al. Safety and efficacy of a standardized Withania somnifera extract in stress and anxiety with hypertension and associated cardiometabolic risk factors: a randomized, placebo-controlled trial. Stress. 2026;29(1):2669544. doi:10.1080/10253890.2026.2669544
- Cheah KL, Norhayati MN, Husniati Yaacob L, Abdul Rahman R. Effect of ashwagandha (Withania somnifera) extract on sleep: a systematic review and meta-analysis. PLoS One. 2021;16(9):e0257843. doi:10.1371/journal.pone.0257843
- Fatima K, Malik J, Muskan F, et al. Safety and efficacy of Withania somnifera for anxiety and insomnia: systematic review and meta-analysis. Hum Psychopharmacol. 2024;39(6):e2911. doi:10.1002/hup.2911
- Marchi M, Grenzi P, Travascio A, et al. The effect of Withania somnifera (ashwagandha) on mental health symptoms in individuals with mental disorders: systematic review and meta-analysis. BJPsych Open. 2025;11(6):e260. doi:10.1192/bjo.2025.10885
- Björnsson HK, Björnsson ES, Avula B, et al. Ashwagandha-induced liver injury: a case series from Iceland and the US Drug-Induced Liver Injury Network. Liver Int. 2020;40(4):825–829. doi:10.1111/liv.14393
- Philips CA, Valsan A, Theruvath AH, et al. Ashwagandha-induced liver injury: a case series from India and literature review. Hepatol Commun. 2023;7(10):e0270. doi:10.1097/HC9.0000000000000270
- McIntyre D, Nguyen P, Kim Y, Meyer B, Salloum M. Ashwagandha (Withania somnifera)-associated liver injury: a scoping review of clinical characteristics and safety considerations. Cureus. 2026;18(5):e109764. doi:10.7759/cureus.109764
- Gannon JM, Forrest PE, Roy Chengappa KN. Subtle changes in thyroid indices during a placebo-controlled study of an extract of Withania somnifera in persons with bipolar disorder. J Ayurveda Integr Med. 2014;5(4):241–245. doi:10.4103/0975-9476.146566
- Williamson EM, Brendler T. Ashwagandha: is it safe? Part 2: a preclinical evidence review. Phytother Res. 2025;40(8):4792–4801. doi:10.1002/ptr.70090
- Cadegiani FA, Kater CE. Adrenal fatigue does not exist: a systematic review. BMC Endocr Disord. 2016;16(1):48. doi:10.1186/s12902-016-0128-4
- Mandlik Ingawale DS, Namdeo AG. Pharmacological evaluation of ashwagandha highlighting its healthcare claims, safety, and toxicity aspects. J Diet Suppl. 2021;18(2):183–226. doi:10.1080/19390211.2020.1741484
- Wiciński M, Fajkiel-Madajczyk A, Kurant Z, et al. Ashwagandha's multifaceted effects on human health: impact on vascular endothelium, inflammation, lipid metabolism, and cardiovascular outcomes. Nutrients. 2024;16(15):2481. doi:10.3390/nu16152481
