Ashwagandha (Withania somnifera)

Dietary supplements, plant adaptogens (local classification)

ATC code: A11JA-ASHWAGANDHA

Brand names – supplements: KSM-66 Ashwagandha, Sensoril Ashwagandha, Ashwagandha Now Foods, Solgar AshwagandhaSupplements are not tested in clinical trials and are not registered as medications.

Updated 24 Sep 2026 · Methodology

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Athletic endurance

Not recommended

Ashwagandha is marketed in fitness communities for muscle strength, VO2max, and testosterone enhancement. Five to seven small RCTs (Wankhede 2015, Ziegenfuss 2018) in trained men aged 18–45 show 1-RM squat and bench press gains of 10–15% and testosterone increases of 14–22% versus placebo. Studies are small (40–60 participants), last 8–12 weeks, and some were industry-funded. IOC, AIS, and ACSM sports nutrition guidelines do not list ashwagandha as an evidence-based ergogenic agent.

Sources

Insomnia and sleep disorders

Not recommended

Ashwagandha is sold for sleep improvement and reduced sleep onset latency. Five RCTs (Langade 2019, Salve 2019, Deshpande 2020) with about 400 participants combined show 15–25 minute reduction in sleep onset and improvements in PSQI in patients with mild insomnia. Studies are small and short (8–10 weeks). insomnia guidelines do not list ashwagandha. CBT-I remains first line for chronic insomnia.

Sources

ICD-10: G47.0 · ICD-11: 7A00

Stress and anxiety

Not recommended

Ashwagandha (Withania somnifera) is an Ayurvedic adaptogen, the most studied over-the-counter supplement for stress reduction. Meta-analyses from 2014–2022 (Pratte, Salve, Lopresti) based on 8–12 small clinical trials show significant reductions in the Perceived Stress Scale (PSS-10) and a 20–30% reduction in salivary cortisol versus placebo. The effect is dose-dependent: the most common dose is 300–600 mg of standardized KSM-66 extract (5% withanolides) once or twice daily. Evidence quality is moderate: small samples (60–130 participants), short studies (8–12 weeks), and high risk of bias. and guidelines for anxiety and stress do not currently include ashwagandha. It is relatively safe in healthy adults, but rare cases of drug-induced liver injury and thyroid stimulation have been reported; ashwagandha is contraindicated in hyperthyroidism, autoimmune disease, and pregnancy. For persistent stress, it is more useful to address sleep, physical activity, and screen for an anxiety disorder or depression. If ashwagandha is taken on its own for stress, do not expect miracles; for marked symptoms, consult a clinician.

Sources

ICD-10: F41.9 · ICD-11: 6B0Z

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

Ashwagandha is the root of the Indian plant Withania somnifera, used in Ayurveda as a «rasayana» (rejuvenator) for over 3000 years. Active constituents include withanolides (steroidal lactones), withanosides, and alkaloids. Cellular models describe HPA axis modulation (cortisol reduction), GABAergic and serotonergic activity, and immunomodulation. Bioavailability of active withanolides in humans is low and depends on extract form.

Safety

Contraindications

Pregnancy (teratogenicity in animal models)
Breastfeeding
Hyperthyroidism and nodular goiter
Hormone-dependent tumours
Autoimmune disease (RA, SLE, MS)
Liver disease
Immunosuppressive therapy

Serious adverse effects

Drug-induced liver injury (DILI) – rare, reported in KSM-66 users at supratherapeutic doses
Thyrotoxicosis in predisposed individuals

Common adverse effects

GI discomfort, nausea, diarrhoea
Drowsiness, sedation
Headache
Rash

Pregnancy: can you take Ashwagandha (Withania somnifera)?

Contraindicated in pregnancy: teratogenicity and abortifacient effects are described in animal models.

Breastfeeding: can you take Ashwagandha (Withania somnifera)?

Not recommended during breastfeeding: safety data are unavailable.

Calculate RID Full profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Russian practice note

In Russia, ashwagandha is sold as a dietary supplement through pharmacy chains and online. Most RCTs use standardized extracts KSM-66 (5% withanolides, root) and Sensoril (10% withanolides, root + leaf). Marketing doses are 300–600 mg once or twice daily, retail 800–3000 ₽/month. Older names «Indian ginseng» and «winter cherry» refer pharmacologically to different plants and should not be confused. Cases of liver dysfunction have been described with high doses and combined Ayurvedic preparations containing heavy metals.

Drug interactions

Ashwagandha may theoretically raise thyroid hormones (T3, T4) – avoid in hyperthyroidism and use cautiously with levothyroxine replacement therapy. Additive sedation is possible with benzodiazepines and hypnotics. Immunostimulatory activity is undesirable in autoimmune disease (RA, SLE, MS) and during immunosuppressive therapy.

Drug–drug interactions

3 pairs found. Sorted from critical to minor.

ModerateLevothyroxine sodiumThyroid hormones

Mechanism

Ashwagandha stimulates thyroid function: in a trial of 50 people with subclinical hypothyroidism, 300 mg twice daily for eight weeks lowered TSH and raised T3 and T4 versus placebo. On top of an already titrated levothyroxine dose, that push adds up. A case of painless thyroiditis with thyrotoxicosis that resolved after stopping the herb has also been published.

Symptoms

Signs of hormone excess: palpitations, fine hand tremor, insomnia, weight loss, heat intolerance, diarrhoea, irritability. The published case also featured night fever and fatigue.

Management

Anyone on levothyroxine should not add ashwagandha without telling whoever titrates the dose. If it is already in use, check TSH, free T4 and T3 at 6–8 weeks and declare the herb at every test: without that detail the result reads as hormone over-replacement and the dose gets cut for the wrong reason. With palpitations or tremor, stop the ashwagandha first.

Sources

Pair details →Levothyroxine sodium →

ModerateMelatoninHypnotics. Melatonin receptor agonists

Mechanism

Both are taken at night and for the same reason, so they end up in the same regimen easily. Ashwagandha has sedative activity of its own and melatonin advances sleep onset; together, next-morning residual drowsiness exceeds either one alone.

Symptoms

Morning drowsiness, a foggy head, slower reactions at the wheel. In older people, a higher risk of falling when getting up at night.

Management

Try one thing at a time for two weeks before adding the other: one is almost always enough. If both are kept, start with the lower melatonin dose and avoid early-morning driving until tolerance is clear.

Sources

Cureus: Painless Thyroiditis Induced by Withania somnifera (Ashwagandha) (2024)

Pair details →Melatonin →

ModerateValeriana officinalis (root extract)Herbal sedative, EMA HMPC traditional herbal medicinal product

Mechanism

Two sedative herbs in the same evening dose. The effect adds up without the packaging warning about it, because each preparation is presented as mild on its own. The combination appears by itself in someone who tries sleep remedies one after another and ends up taking them together.

Symptoms

Daytime sedation, difficulty waking, clumsiness when driving or operating machinery. With alcohol or any added sedative drug the effect grows.

Management

Pick one of the two and judge the result over two weeks. If insomnia persists despite the combination, the way forward is not adding a third herb but reviewing the cause: apnoea, night pain, late caffeine or an activating drug.

Sources

Cureus: Painless Thyroiditis Induced by Withania somnifera (Ashwagandha) (2024)

Pair details →Valeriana officinalis (root extract) →

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Frequently asked

What is Ashwagandha (Withania somnifera) used for?

Ashwagandha (Withania somnifera) is evaluated for the following indications with varying evidence strength: Athletic endurance (evidence tier D), Stress and anxiety (evidence tier D), Insomnia and sleep disorders (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Ashwagandha (Withania somnifera)?

Common side effects of Ashwagandha (Withania somnifera) (≥ 1 in 100): GI discomfort, nausea, diarrhoea, Drowsiness, sedation, Headache, Rash. See the Safety section for uncommon and serious reactions.

Is Ashwagandha (Withania somnifera) safe during pregnancy?

Contraindicated in pregnancy: teratogenicity and abortifacient effects are described in animal models.

Is Ashwagandha (Withania somnifera) compatible with breastfeeding?

Not recommended during breastfeeding: safety data are unavailable.

Who should not take Ashwagandha (Withania somnifera)?

Ashwagandha (Withania somnifera) is contraindicated in: Pregnancy (teratogenicity in animal models); Breastfeeding; Hyperthyroidism and nodular goiter; Hormone-dependent tumours; Autoimmune disease (RA, SLE, MS). Full list in the Safety section.

Other drugs in this group

Astaxanthin, Bacopa monnieri (brahmi), Beta-carotene, Beta-1,3/1,6-D-glucan (yeast or oat), Creatine monohydrate, Mixed tocopherols, Pterostilbene (dimethyl resveratrol analogue), Spirulina