Know2eat

Ashwagandha

Withania somnifera

Traditional Formulas

What ashwagandha may help with

Ranked by how strong the human evidence is — best supported first.

Best supportedStress and anxietyModerate evidence· 3 sources

Then, in order

About Ashwagandha

The root of a small nightshade shrub, used in Ayurveda as a rasayana — a category of tonic preparation rather than a remedy for a named condition. Modern products are usually concentrated root extracts standardised to withanolides.

Ashwagandha has more randomised trials behind it than most botanicals, and the results for perceived stress point fairly consistently in one direction. The caveats are large: trials are small, run 8 weeks or less, come overwhelmingly from a handful of Indian centres, and a majority are funded or conducted by the manufacturer of the branded extract being tested. Root-only and root-plus-leaf extracts are chemically different products sold under the same name.

Sold as
Standardised root extract capsule, Root powder (churna), Tablet, Tincture, Gummy
Standardised to
Commonly 1.5–5% withanolides; branded extracts state their own assay — a product without this marker may not resemble what was studied.
Also known as
Indian winter cherry, Indian ginseng, Asgandh

Regulation: A dietary supplement in the US with no pre-market efficacy or safety review. Denmark restricted its sale over endocrine and liver concerns, and several national regulators have issued advisories about liver injury reports.

What the research used

The amounts, forms and durations published trials of Ashwagandha actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

  • Studied for Perceived stress and anxiety scales

    240–600 mg

    Moderate

    Standardised root extract, once or twice daily · ≥5% withanolides in most trials · 8 weeks

    The two most-studied branded extracts were tested at 300 mg twice daily and 125–250 mg daily respectively and are not interchangeable. Most of these trials were sponsored by the extract manufacturer.

  • Studied for Strength and body composition in resistance training

    500–600 mg

    Limited

    Standardised root extract · 8–12 weeks

    Small trials in untrained men, mostly from one research group, with the usual difficulty of separating a supplement effect from the training programme itself.

  • Studied for Sleep quality

    300–600 mg

    Limited

    Root extract, evening dose · 6–12 weeks

    Trials use subjective sleep questionnaires far more often than actigraphy or polysomnography, and placebo response on those questionnaires is substantial.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.

  • Evening

    Not enough

    Sleep trials dosed in the evening, but no trial has compared morning against evening dosing, so the convention rests on the outcome being measured rather than on pharmacology.

    Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

  • With food

    Not enough

    Commonly taken with food because the powdered root is bitter and can unsettle an empty stomach. Absorption differences with food have not been characterised.

    Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

The evidence in depth

Best supported: Moderate

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.

Stress and anxiety

Mental Wellbeing
Moderate evidence

Several randomised trials report lower perceived-stress and anxiety scores after 8 weeks compared with placebo, and meta-analyses find the effect consistent in direction. Confidence is held back by small samples, short follow-up, near-universal manufacturer funding and reliance on self-report scales.

What may be going on: Withanolides have been linked to reduced cortisol output and to GABAergic activity in preclinical work, though the human mechanism is not established.

Moderate evidence. Several human studies point the same way, with real caveats.

View the 3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Exercise performance

Muscle & Physical Performance
Limited evidence

Small trials report modest gains in maximal strength and oxygen uptake alongside a training programme. The studies are short, mostly in untrained participants, and have not been replicated by independent groups.

Limited evidence. Early human work, or mostly lab and animal research.

View the 4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Sleep quality

Sleep
Limited evidence

Some trials report improvements in self-reported sleep onset and quality, mainly in people who reported poor sleep at baseline. The objective sleep data are thin and the questionnaires used are highly placebo-sensitive.

Limited evidence. Early human work, or mostly lab and animal research.

View the 3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Energy metabolism

Energy & Metabolism
Not enough evidence

Evidence is limited for ashwagandha and fatigue or energy as such. Where fatigue improved in trials it was usually a secondary outcome measured on the same questionnaire as stress, which makes the two hard to separate.

Not enough evidence. Not enough human research to say anything useful yet.

View the 4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

  • Worth knowing

    Liver injury has been reported

    Published case series describe cholestatic and mixed liver injury developing weeks to months after starting ashwagandha, occasionally severe. Several national regulators have issued advisories. Anyone with existing liver disease should avoid it, and jaundice, dark urine or right-upper-abdominal pain warrants stopping and medical review.

  • Interaction

    Thyroid hormone effects

    Interacts withLevothyroxine, carbimazole, methimazole

    Ashwagandha has been associated with rises in T3 and T4 and with cases of thyrotoxicosis. It can destabilise dosing for people on levothyroxine or antithyroid drugs and is a poor choice in hyperthyroidism.

  • Avoid

    Avoid in pregnancy

    Ashwagandha has traditional use as an abortifacient and animal data raise concern. It should not be used in pregnancy, and there is no safety data for breastfeeding.

  • Interaction

    Additive sedation and immune-drug interaction

    Interacts withBenzodiazepines, CNS depressants, immunosuppressants

    Sedative effects may add to benzodiazepines, alcohol and other central nervous system depressants. Because it appears to increase some immune-cell activity, it is generally avoided by people on immunosuppressants after transplant or for autoimmune disease.

  • Worth knowing

    Ayurvedic sourcing and heavy metals

    Independent testing of imported Ayurvedic products has repeatedly found lead, mercury and arsenic above safe limits, sometimes deliberately added in rasa shastra preparations. Third-party heavy-metal testing is worth insisting on.

  • Allergy

    Nightshade family

    Withania somnifera is a Solanaceae plant, like tomato, potato and aubergine. People with established nightshade sensitivity may react.

Evidence ratings on this page: 1 moderate evidence, 2 limited evidence, 1 not enough evidence.

Supplements are sold in the US without pre-market review of efficacy or safety. Nothing on this page is a recommendation to take Ashwagandha, or a dose to follow.