Ashwagandha and cortisol supplements are among the best-selling wellness products of 2026, yet doctors are divided on whether they actually deliver. The short answer: the evidence is real but modest, and context matters enormously. Whether they help depends on who is taking them, why, and what else is going on in that person’s life.
A press release from PureHealth Research this week highlighted surging consumer demand for ashwagandha paired with magnesium for stress management, while Dr. Amir Khan cautioned in a widely shared article that popular adaptogens “may not be the answer to everything.” Both statements are accurate. This article unpacks the research, explains what doctors are actually debating, and helps you decide whether these supplements are worth exploring for your situation.
What Is Cortisol and Why Does It Matter?
Cortisol is a steroid hormone produced by the adrenal glands. It follows a natural daily rhythm: levels peak in the early morning (helping you wake up and feel alert) and gradually decline through the day, reaching their lowest point around midnight. This cycle is known as the cortisol awakening response.
Cortisol plays essential roles in energy regulation, immune function, blood sugar balance, and the body’s response to stress. It is not inherently harmful. The problem arises when the stress system stays chronically activated. Poor sleep, sustained psychological stress, overtraining, or certain medical conditions can push cortisol outside its normal daily rhythm. Chronically elevated cortisol is associated with disrupted sleep, increased appetite, fatigue, and over time, changes in body composition. Many people who feel “high cortisol,” however, have levels within the normal clinical range. A blood or salivary cortisol test can clarify whether levels are genuinely elevated before turning to supplements.
Ashwagandha and Cortisol: What the Research Actually Shows
Ashwagandha (Withania somnifera) is the most studied adaptogen for stress and cortisol. Adaptogen is a functional category, not a pharmacological classification. It refers to botanicals that may support the body’s ability to adapt to physical and psychological stressors.
Several clinical trials have examined ashwagandha’s effect on cortisol and subjective stress measures. A double-blind, randomised, placebo-controlled trial published in Medicine (2019) found that adults taking 240 mg of ashwagandha root extract daily for 60 days showed significantly reduced serum cortisol compared to placebo, alongside lower scores on validated stress scales. A 2012 study in the Indian Journal of Psychological Medicine using 300 mg of KSM-66 root extract twice daily reported similar reductions in cortisol and improved self-reported stress over eight weeks.
A 2021 review in Nutrients concluded that ashwagandha supplementation “may be associated with reductions in stress and anxiety measures,” but noted that most trials are of short duration, involve relatively small sample sizes, and use varying extract types and doses. Standardised root extracts (such as KSM-66 and Sensoril) tend to appear in the higher-quality trials; leaf and whole-plant preparations are less studied.
Dosage markers from the evidence base
- Most positive trials use 300–600 mg of standardised root extract daily
- Effects are typically observed over 6–12 weeks, not days
- Bioavailability may be improved when taken with a small amount of fat
- Extract standardisation (percentage of withanolides) matters more than raw milligrams
Ashwagandha: Cautions and who should be careful
Ashwagandha has a reasonably well-established short-term safety profile in healthy adults, but caution is warranted in several situations:
- Thyroid conditions: Ashwagandha may interact with thyroid hormone levels. Those taking thyroid medication (levothyroxine, for example) should consult their prescriber before use, as it may require dose adjustment.
- Immunosuppressants: Ashwagandha may stimulate immune activity, which could theoretically interfere with immunosuppressive therapy (post-transplant medications, for example).
- Sedatives and CNS depressants: Ashwagandha has mild calming properties and may potentiate the effects of benzodiazepines, sedatives, and sleep medications. Consult a healthcare professional before combining.
- Pregnancy and nursing: Ashwagandha is not recommended during pregnancy, as some evidence suggests it may stimulate uterine contractions. Those who are breastfeeding should avoid it until more safety data is available.
- Autoimmune conditions: Due to its potential immune-modulating effects, people with rheumatoid arthritis, lupus, Hashimoto’s, or similar conditions should consult a doctor before use.
- Liver health: A small number of case reports have linked high-dose ashwagandha use to liver injury. The causality is not established, but those with existing liver conditions should seek medical advice first.
Magnesium for Stress: The Evidence
Magnesium is an essential mineral involved in over 300 enzymatic reactions, including the regulation of the nervous system and the HPA axis. Deficiency is more common than many assume: research suggests that a significant proportion of adults in Western countries do not meet recommended dietary intakes through food alone, and chronic stress itself depletes magnesium stores.
A 2017 review in Nutrients examining 18 studies on magnesium and stress found that supplementation “may be associated with reduced subjective anxiety” in individuals with low baseline magnesium status. The evidence for magnesium directly lowering cortisol is less consistent than for ashwagandha. The more supported picture is that magnesium may help regulate the nervous system’s stress reactivity rather than directly suppressing cortisol output.
Magnesium glycinate and magnesium threonate are the forms most commonly cited in research on stress and sleep, due to their higher bioavailability and reduced laxative effect compared to magnesium oxide. Typical doses in trials range from 200–400 mg elemental magnesium daily, though optimal amounts vary by individual and diet.
Magnesium: Cautions and who should be careful
- Kidney disease: The kidneys regulate magnesium excretion. People with kidney disease or reduced kidney function should not take magnesium supplements without medical supervision, as excess accumulation may be dangerous.
- Medications: Magnesium may reduce the absorption of certain antibiotics (fluoroquinolones, tetracyclines) and bisphosphonates (used for bone density). It can also interact with diuretics and some heart medications. Space doses appropriately and consult a pharmacist.
- Digestive sensitivity: High doses of magnesium (particularly oxide or citrate forms) can cause loose stools or diarrhoea. Starting at a lower dose and building up gradually is advisable.
- Pregnancy and nursing: Magnesium is generally considered safe in dietary amounts during pregnancy and nursing, but supplemental doses should only be taken under medical guidance.
What Doctors and Researchers Say
The medical community is not uniformly sceptical of adaptogens, but it is appropriately cautious. Dr. Amir Khan’s recent comments reflect a legitimate concern: that consumers are treating adaptogenic supplements as solutions to lifestyle problems that supplements cannot fix. Chronic work stress, poor sleep hygiene, a sedentary routine, and inadequate nutrition are not problems ashwagandha can resolve on its own.
At the same time, researchers who study adaptogenic botanicals point out that dismissing the evidence entirely overstates the uncertainty. Dr. Priyanka Wali, an integrative medicine physician and clinical researcher, has noted in professional contexts that ashwagandha’s HPA-axis effects are among the more consistently replicated findings in botanical medicine. The concern is not that it does nothing. The concern is that people may take it instead of addressing the root cause, rather than alongside meaningful lifestyle change.
The nuanced position most evidence-based practitioners land on: these supplements may offer incremental benefit for people under genuine stress, in the context of adequate sleep, reasonable diet, and managed workload. They are unlikely to produce dramatic effects on their own, and for people whose cortisol is clinically normal, the benefit may be minimal.
Who Might Benefit — and Who Should Be Cautious
Based on the available evidence, the following groups may find ashwagandha and/or magnesium supplementation worth discussing with a healthcare provider:
- Adults with confirmed elevated cortisol (via testing) alongside high subjective stress and no medical cause identified
- People with poor sleep and low magnesium intake who do not eat a diverse diet rich in leafy greens, legumes, and whole grains
- Adults managing ongoing occupational or life stress who have already addressed sleep, exercise, and dietary basics
On the other hand, these supplements are unlikely to be the right first step for:
- People with undiagnosed or untreated medical conditions causing cortisol dysregulation (such as Cushing’s syndrome or adrenal insufficiency, conditions that require clinical management)
- Those on medications with known interaction risks (see Cautions sections above)
- People hoping to replace sleep or stress management with a supplement
- Children and adolescents, for whom safety data in younger populations is not established
How to Evaluate a Supplement Before Buying
The supplement industry is largely self-regulated, which means quality varies significantly between brands. Here is what to look for when evaluating an ashwagandha or magnesium product:
- Third-party certification: Look for NSF International, USP, Informed Sport, or Informed Choice on the label. These confirm the product contains what it claims, in the stated amounts, free from common contaminants.
- Extract standardisation (ashwagandha): Choose products specifying extract type and withanolide percentage. KSM-66 (root-only, 5% withanolides) and Sensoril are the extracts most commonly used in positive clinical trials.
- Magnesium form: Glycinate, threonate, and malate are better absorbed and gentler on digestion than magnesium oxide. “Magnesium” without a form name often means oxide, the cheapest and least bioavailable option.
- Dose alignment: Compare to evidence-based ranges (300–600 mg ashwagandha extract; 200–400 mg elemental magnesium daily). Doses well below these thresholds are unlikely to produce studied effects. Quality ashwagandha typically retails in the $20–$50 range per month; magnesium in the $15–$40 range, depending on form (prices as of 2026).
Frequently Asked Questions
How long does ashwagandha take to work for stress?
Clinical trials typically show measurable effects after 6–8 weeks of consistent daily use. Some individuals report subjective changes in the first two to three weeks, but the more robust cortisol-related findings in research emerge over a longer period. Ashwagandha is not a fast-acting intervention.
Can you take ashwagandha and magnesium together?
Yes, the two are commonly used together and no significant interactions between them have been identified in the literature. Both are generally considered complementary for stress and sleep support. That said, if you are taking other medications or supplements, a pharmacist review of your full stack is worth the time.
Do cortisol-support supplements actually lower cortisol in blood tests?
Some studies have shown statistically significant reductions in serum or salivary cortisol in participants taking ashwagandha, compared to placebo. The reductions are real but modest — typically not dramatic normalisation of clinically elevated cortisol. For people whose cortisol is within the normal reference range, changes may be too small to detect on a standard test.
Are there foods that help manage cortisol naturally?
Diet plays a meaningful role in stress regulation. Magnesium-rich foods (dark leafy greens, pumpkin seeds, dark chocolate, legumes) support the nervous system. Stable blood sugar, achieved through regular meals with adequate protein, fat, and fibre, reduces the physiological triggers for cortisol spikes. Reducing caffeine, particularly after midday, may also help regulate the cortisol rhythm.
When should I see a doctor instead of trying supplements?
If you experience symptoms that may indicate clinically abnormal cortisol (unexplained weight gain concentrated around the abdomen, facial rounding, easy bruising, muscle weakness, or conversely extreme fatigue, low blood pressure, and darkening of the skin), please see a doctor before reaching for supplements. These can be signs of Cushing’s syndrome or adrenal insufficiency, conditions that require clinical diagnosis and management, not over-the-counter solutions.
Bottom Line
The debate around ashwagandha and cortisol supplements is not a simple “it works / it doesn’t” question. The evidence supports that standardised ashwagandha root extract and adequate magnesium may modestly support the body’s stress response in people who are genuinely stressed, deficient in magnesium, or both. These are real effects in real trials, not marketing fiction. But the magnitude of benefit is incremental, not transformative, and both supplements work best alongside sleep, movement, and actual stress reduction rather than as a substitute for those things.
Dr. Khan’s caution is well-placed: popular wellness trends can outrun the evidence, and adaptogens are no exception. The answer is not to dismiss ashwagandha wholesale, but to approach it with the same measured expectations the research itself suggests. If you are considering these supplements, choose third-party tested products with standardised extracts, run the decision by your doctor or pharmacist if you are on medication, and give it at least eight weeks before drawing conclusions.
Explore Further
If you are researching adaptogens as part of a broader focus and energy supplement stack, our guide to the best nootropics and focus supplements of 2026 covers evidence-reviewed options across the cognitive and stress-resilience categories, including several that pair well with ashwagandha.
For women looking to address stress, fatigue, and nutritional gaps comprehensively, our best women’s multivitamins for 2026 roundup highlights formulas that include meaningful magnesium and B-vitamin complexes alongside standard micronutrients.