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Ashwagandha has become the ingredient everyone name-drops the moment stress comes up — in gym forums, in group chats, on wellness TikTok, usually paired with some version of the claim that it “lowers cortisol.” That much isn’t invented. But the story behind it is narrower than the headlines suggest, and if you like knowing what a study actually found before you start taking something daily, this is worth five minutes. What Cortisol Does — and Why Ashwagandha Gets Linked to It Cortisol is your main stress hormone, released by your adrenal glands whenever your brain flags something as urgent — a deadline, an argument, actual danger. In short bursts, it’s useful: it sharpens focus and mobilises energy. The problem is chronic elevation, cortisol that stays high because life stays demanding, which tracks with poor sleep, low mood, and wider strain on the body over time. Ashwagandha (Withania somnifera) is classed as an adaptogen — a category of plants used in Ayurvedic medicine for centuries on the idea that they help the body regulate its stress response rather than sedate it outright. A 2025 systematic review and meta-analysis in BJPsych Open pooled the available randomised controlled trials and found a significant effect of ashwagandha on cortisol levels compared with placebo, alongside reductions in perceived stress and anxiety scores.[1] Significant here means the effect is real and unlikely to be down to chance. It doesn’t mean dramatic, and it doesn’t mean identical for everyone who takes it. “The premise behind adaptogens isn’t sedation. It’s regulation — helping the body’s stress response come back down once the immediate need for it has passed.” The Study Behind the Number You’ve Probably Seen Most of the specific percentages floating around online trace back to one trial: a 2012 double-blind, placebo-controlled study of 64 adults with a history of chronic stress, published in the Indian Journal of Psychological Medicine. Participants took 300mg of a high-concentration, full-spectrum ashwagandha root extract twice a day for 60 days. By the end, the treatment group’s serum cortisol had dropped 27.9% relative to placebo, alongside improvements across several stress and anxiety scales.[2] That extract is now sold under the brand name KSM-66, one of the most-studied standardised ashwagandha extracts on the market. Worth being precise about what this does and doesn’t prove: it was one trial, one dose, one specific extract, in adults who were already chronically stressed. It’s not a guarantee of what happens with a different formulation, a different dose, or someone who isn’t especially stressed to start with. 27.9% The drop in serum cortisol seen in a 60-day trial of ashwagandha root extract, versus placebo If you’re going to try it, the extract and the dose matter more than most labels let on. Our Ashwagandha KSM-66 uses that same standardised, full-spectrum 12:1 root extract at 1281mg per capsule, boosted with black pepper extract (95% piperine) for absorption — one capsule, once a day, rather than a vague scoop of powder. The Golden Pick Ashwagandha KSM-66 1281mg KSM-66 extract · piperine boosted £12.95● OUT OF STOCK View Ashwagandha KSM-66 → The UK Safety Review Most Ashwagandha Content Skips Here’s the part most ashwagandha content leaves out. In 2024, the UK Food Standards Agency opened a call for evidence on ashwagandha specifically, citing “potential risks to health from consuming ashwagandha in food supplements” — flagging case reports linking it to effects on thyroid hormone levels and, less commonly, liver toxicity.[3] The FSA’s own toxicology committee described the liver cases as consistent with an idiosyncratic reaction: rare, and not predictable from dose alone. Denmark restricted ashwagandha in food supplements back in 2020 on similar grounds, and the UK still hasn’t settled on formal usage limits — the review is genuinely ongoing. It’s also worth being straight that there’s no EFSA-authorised health claim for ashwagandha to point to here. The EU’s assessment of botanical health claims has been on hold since 2010, so nothing in this space carries that particular stamp — what exists is evidence from individual clinical trials, which is real, but narrower.[4] We’ve covered the fuller regulatory picture in Is Ashwagandha Legal in the UK: Regulations and Availability, if you want the detail. If you’re pregnant, breastfeeding, on thyroid medication, or managing a liver condition, this is a genuine talk-to-your-GP-first situation, not a personal judgement call. Taking It Sensibly Give it time — most trials run 8 to 12 weeks before measuring results, so four days won’t tell you much. Match the studied dose range — most positive trials sit between 250mg and 600mg a day of standardised extract, not a rough guess at a powder serving. Take it daily, not as a rescue remedy — the effect builds through consistent use rather than showing up after one dose. Check with your GP first if thyroid medication, pregnancy, or liver health are part of your picture. Ashwagandha’s popularity has outpaced the caution around it, which tends to happen with anything that goes from ancient remedy to Instagram shorthand in a few years. The cortisol research is real and worth taking seriously. It’s also tied to specific extracts, specific doses, and people who were properly stressed to begin with — not a blanket promise. Read the label, give it the weeks it needs, and don’t skip the GP conversation if your history calls for it. That’s the standard worth holding it to. Frequently asked questions How long does ashwagandha take to work for stress? Most clinical trials measure change at the 8 to 12 week mark, though some people report feeling a bit calmer within 2 to 4 weeks. Give it the full 8 weeks at a consistent dose before deciding whether it’s doing anything for you. Can you take ashwagandha every day, long-term? Most of the published trials run for 8 to 12 weeks continuously, and that’s the window the safety data actually covers well. Longer-term daily use hasn’t been studied as thoroughly, which is part of why UK regulators are still reviewing it. If you want to use it beyond a few months, cycling off periodically and checking in with your GP is the sensible approach, especially if you’re on other medication. What’s the best time of day to take ashwagandha? There’s no strict rule. Some people take it in the evening, since early research points to a mild calming effect; others take it with breakfast alongside other supplements, purely for consistency. We’ve gone into more detail on timing in When Is the Best Time to Take Ashwagandha for Optimal Benefits. Is ashwagandha the same as other adaptogens like rhodiola or ginseng? No. They’re grouped together as adaptogens because they’re all believed to help the body manage stress, but they’re different plants with different evidence bases and different safety profiles. Ashwagandha currently has the largest body of clinical research behind it for cortisol specifically, while rhodiola’s research leans more toward fatigue and mental performance. They’re not interchangeable, and combining several without guidance isn’t something we’d recommend. Sources BJPsych Open — systematic review and meta-analysis of ashwagandha supplementation on cortisol, stress and anxiety in adults, cited for the pooled effect on cortisol levels. cambridge.org Chandrasekhar K, Kapoor J, Anishetty S (2012), Indian Journal of Psychological Medicine — the randomised, placebo-controlled trial cited for the 27.9% serum cortisol reduction figure. journals.sagepub.com Nutrition Insight, reporting on the UK Food Standards Agency’s 2024 call for evidence on ashwagandha safety, cited for the FSA’s thyroid/liver toxicity concerns and the Danish restriction. nutritioninsight.com Nutrition Insight, on the EU’s botanical health claims assessment process, cited for the absence of an EFSA-authorised health claim for ashwagandha. nutritioninsight.com At Oxford Origins, your wellbeing is our priority, and although we pride ourselves on our expertise in nutrition and supplementation, it's important to acknowledge the individuality of each person. Articles published by Oxford Origins are not intended to treat, diagnose, cure or prevent any disease, or replace the advice of your GP. We always recommend consulting with a healthcare provider if you encounter any health concerns, and we'll always be here to support you so you're never alone on your journey.

Ashwagandha can measurably lower cortisol, and real trials back that. But UK regulators are reviewing its safety too. Here's what actually holds up.

Ashwagandha turns up in most stress-relief conversations now, and for once there's real trial data behind it — not just centuries of Ayurvedic tradition. The question is what that data actually says, because “lowers cortisol” and “makes you feel less stressed” turn out to be two different claims. And right now, the UK's food safety regulator has ashwagandha under active review. Here's what the research actually supports, what it doesn't, and what to check before you buy anything. What ashwagandha is actually being asked to do Ashwagandha (Withania somnifera) is a root used in Ayurvedic medicine for centuries, generally as a tonic for resilience under strain — what modern researchers call an “adaptogen.” The narrower claim being tested in labs today is whether it lowers cortisol, the hormone your adrenal glands release when your body registers a threat, whether that threat is a work deadline or an actual emergency. Chronically elevated cortisol is linked to poor sleep and low mood, among other things, so a supplement that turns the dial down is an obvious thing to want to work. The cortisol evidence, specifically The most-cited single trial here is a 2012 study out of Asha Hospital in Hyderabad: 64 adults with self-reported chronic stress took either 300mg of KSM-66 ashwagandha extract twice a day, or a placebo, for 60 days.[1] The ashwagandha group's serum cortisol dropped 27.9%, against a 7.9% drop in the placebo group — a meaningful gap for a two-month trial. 27.9% Average drop in serum cortisol after 60 days of KSM-66 ashwagandha, vs. 7.9% on placebo That's one trial, though, and supplement research doesn't always replicate outside the original lab. The stronger evidence is a 2025 systematic review pooling eight randomised controlled trials across 488 adults, which found a statistically significant average cortisol reduction compared with placebo.[2] Across different doses and extract types, cortisol genuinely does come down. Why “lower cortisol” isn't the same as “feel less stressed” Here's the part most ashwagandha content skips. That same 2025 review found no significant improvement on the Perceived Stress Scale — the standard questionnaire researchers use to measure how stressed people say they feel.[2] Cortisol fell. Reported stress, in the same participants, largely didn't move. Maybe eight weeks isn't long enough for a hormonal shift to show up in how someone feels day to day. Maybe cortisol just isn't the right lever for subjective stress in the first place. Either read is honest. Neither one is the confident “ashwagandha crushes stress” framing you'll see on most supplement sites. What UK regulators are actually looking at right now This is the part worth knowing before you buy anything. The UK's Food Standards Agency ran a formal call for evidence on ashwagandha's safety in 2024 and is still working through what it means for future guidance, after risk assessments flagged possible effects on thyroid hormones, liver function and blood sugar at some doses.[3] Denmark has already restricted ashwagandha in food supplements over similar concerns, and other EU food safety bodies are watching closely. None of this means ashwagandha is dangerous for most healthy adults at typical doses — the concerns centre on specific groups, not a blanket problem.[4] But it does mean skipping it in pregnancy or while breastfeeding, and talking to a doctor first if you have a thyroid condition, liver disease, or take thyroid, blood sugar or blood pressure medication. We've gone into the regulatory detail properly in a separate piece on where ashwagandha actually stands in UK law — worth a read if this is new information to you. It's also worth knowing that ashwagandha has no authorised EFSA health claim, in either direction — inconsistent extracts and unclear mechanisms have kept it off the approved list for years.[5] That's not the same as “unsafe.” It just means nobody gets to print a guaranteed-benefit claim on the box, including us. If you're going to take it, what actually matters Assuming none of the above rules you out, the studies that showed results used specific things: a standardised KSM-66 extract, roughly 600mg a day, taken consistently for eight weeks or longer.[1] Loose ashwagandha powder from an unlabelled source, taken occasionally, isn't the same product the trials tested. The extract type — KSM-66 and Sensoril are the two most-studied standardised extracts; generic “ashwagandha root powder” with no extraction ratio listed is a different, less-tested product. The dose — most trial doses land around 600mg a day; considerably less than that is unlikely to match the results in the studies. Absorption support — black pepper extract (piperine) is commonly added because it measurably improves uptake of the active compounds. Third-party testing — a UK-manufactured product tested by an independent lab is a reasonable minimum bar for a herbal extract under this much regulatory scrutiny. Oxford Origins' Ashwagandha KSM-66 uses that same standardised extract — a 12:1 full-spectrum KSM-66 formula, the same branded ingredient behind the Chandrasekhar trial — in a single 1281mg capsule, boosted with 95% piperine black pepper extract for absorption, and manufactured in the UK to BRC Grade AA standards. KSM-66 is, as the name on the label suggests, widely considered the gold standard of ashwagandha extract; it's the ingredient most of the research above is actually about, even if no single capsule can promise you the exact numbers from a 64-person trial. The Golden Pick Ashwagandha KSM-66 KSM-66 12:1 extract · 1281mg · black pepper £12.95● OUT OF STOCK View Ashwagandha KSM-66 → It's currently out of stock while we restock — you can still view the full label on the product page and switch on a back-in-stock notification. The honest summary The evidence for ashwagandha and cortisol is genuinely better than most adaptogen claims you'll come across. It's just narrower than the marketing suggests. Cortisol comes down, trial after trial. Whether that translates into feeling calmer is still an open question, and whether it's right for you depends more on your health history than most supplements on the shelf. That's not a reason to write it off. It's a reason to check the label, check your own situation, and not expect a miracle in a capsule. Frequently asked questions How long does ashwagandha take to lower cortisol? Most trials measure cortisol at eight weeks, including the most-cited KSM-66 study, so give it that long before judging results. Some people notice sleep or mood changes sooner, but the cortisol data specifically comes from eight-week-plus trials, not days. For general dosing and timing guidance, see our piece on the best time to take ashwagandha. Can you take ashwagandha every day, long-term? Most published trials run 8–12 weeks, so that's the timeframe with actual safety data behind it. Long-term daily use hasn't been studied as thoroughly, which is part of why UK regulators are still reviewing it. If you want to take it long-term, it's worth cycling off periodically and checking in with a GP, especially if you're on any regular medication. Is ashwagandha safe to take in the UK right now? It's legal and widely sold, but the Food Standards Agency has an active safety review open, and it isn't recommended in pregnancy, while breastfeeding, or for people with thyroid or liver conditions without medical advice. We've covered the full regulatory picture in this article. What's the difference between KSM-66 and other ashwagandha extracts? KSM-66 is a specific, patented 12:1 full-spectrum root extract, standardised to contain the full range of naturally occurring compounds rather than an isolated fraction. It's the extract used in most of the cortisol trials, including the 2012 Chandrasekhar study. Other products use different extraction methods, like Sensoril (leaf-and-root based), or unstandardised powder, which makes it harder to compare results between products. Sources Chandrasekhar K, Kapoor J, Anishetty S (2012), Indian Journal of Psychological Medicine — randomised controlled trial of KSM-66 ashwagandha root extract on serum cortisol and stress in adults. https://pubmed.ncbi.nlm.nih.gov/23439798/ Albalawi AA et al. (2025), systematic review and meta-analysis of 8 RCTs (488 adults) on ashwagandha, cortisol and perceived stress. https://journals.sagepub.com/doi/abs/10.1177/02601060251363647 UK Food Standards Agency — call for evidence and summary of responses on the safety of ashwagandha food supplements. https://www.gov.uk/government/consultations/summary-of-responses-to-call-for-evidence-on-ashwagandha/summary-of-responses-to-call-for-evidence-on-ashwagandha Patient.info — ashwagandha safety, contraindications and drug interactions overview. https://patient.info/features/diet-and-nutrition/ashwagandha NutraIngredients — overview of EU health claim law and the absence of an authorised EFSA claim for ashwagandha. https://www.nutraingredients.com/Article/2025/10/23/breaking-down-the-eu-law-on-mind-health-supplements/ At Oxford Origins, your wellbeing is our priority, and although we pride ourselves on our expertise in nutrition and supplementation, it's important to acknowledge the individuality of each person. Articles published by Oxford Origins are not intended to treat, diagnose, cure or prevent any disease, or replace the advice of your GP. We always recommend consulting with a healthcare provider if you encounter any health concerns, and we'll always be here to support you so you're never alone on your journey.