AshwagandhaBotanical
300–600 mg/day
Generalized anxiety — WFSBP/CANMAT provisional recommendation. Root extract standardized to 5% withanolides.
For informational use only; not medical advice. Check with your doctor before starting, particularly if taking other meds.
Ashwagandha (Withania somnifera) is an evergreen shrub native to parts of India, Africa, and the Middle East.
Its root — and sometimes its leaf — has been used in Ayurvedic medicine for centuries [1].
It is not a vitamin or mineral. There is no dietary requirement for it and no such thing as an ashwagandha deficiency [2].
In the US it is sold as a dietary supplement, not a drug, so the FDA does not review it for safety or effectiveness before it reaches shelves [1].
What the Evidence Actually Supports
- Stress and cortisolLikely helps
A 2021 systematic review pooling 7 RCTs (491 adults) found ashwagandha reduced self-reported stress and anxiety, and lowered serum cortisol, versus placebo over 6–8 weeks [2].
Most of those trials were small and published in a narrow set of journals, so NIH ODS reads the finding as promising rather than settled. [2] - SleepPossibly helps
A 2021 meta-analysis of 5 sleep studies (372 adults) found a small but statistically significant improvement versus placebo [2].
NCCIH's own consumer review is more cautious, describing the evidence for insomnia as suggestive rather than established [1]. [2] - Anxiety specificallyPossibly helps
The two US government reviews disagree, and we are not resolving it for you.
NCCIH says evidence on anxiety specifically is unclear [1]. NIH ODS describes multiple RCTs, including that 7-trial review, showing a real reduction [2]. [1] - Athletic performancePossibly helps
Another live disagreement. A 2021 Bayesian meta-analysis of 13 trials found ashwagandha outperformed placebo on physical-performance measures [9].
NCCIH's 2023 fact sheet says there isn't enough evidence to tell [1]. The meta-analysis is newer and more specific; NCCIH's bar for "enough evidence" is higher. [9] - Male testosterone and sperm qualityPossibly helps
NCCIH notes limited evidence that 2 to 4 months of use may raise testosterone and improve sperm quality in men [1].
For women's fertility, the same review finds there isn't enough evidence to say anything. [1]
Forms, If You're Comparing Supplements
KSM-66The most-studied form in stress and anxiety trials
Elemental contentRoot-only extract, standardized to at least 5% withanolides
AbsorptionCommonly supplied as 300-mg capsules; trials typically used two per day (~600 mg/day)
Best forThe most-studied form in stress and anxiety trials [2]
Sensoril / ShodenSleep trials. Note that root and leaf differ chemically — this is not interchangeable with a root-only extract
Elemental contentRoot-and-leaf extracts, standardized to withanolide-glycoside content instead — Shoden delivers 21 mg per 60-mg capsule
AbsorptionFar more concentrated, so trial doses are much smaller (120 mg/day for Shoden)
Best forSleep trials. Note that root and leaf differ chemically — this is not interchangeable with a root-only extract [2]
Whole root powder or granulesThe traditional preparation. Hard to compare against extract doses
Elemental contentUnstandardized
AbsorptionRequires far larger amounts — up to 12,000 mg/day of granules (~6,000 mg/day root powder) in reviewed trials
Best forThe traditional preparation. Hard to compare against extract doses [2]
Side Effects
- Short-term tolerability
Generally well tolerated for up to about 3 months. Safety beyond that window has not been established [1].
Common mild effects: stomach upset, loose stools, nausea, drowsiness. [1]
Precautions
- Liver injury
Liver injury is the serious signal here. Case reports from the US, Iceland, India, and Poland describe acute cholestatic or mixed-pattern hepatitis — jaundice, itching, nausea, fatigue [2].
Reported at roughly 450–1,350 mg/day over 1 week to 4 months. One case series across 3 Indian tertiary hospitals documented 8 patients with severe liver injury between 2019 and 2022 [3].
Australia's TGA has logged 11 or more possible cases, prompting 2024 and 2026 safety alerts [6]. [2] - Thyroid
Thyroid effects run in both directions, and the sources conflict.
A small trial found 600 mg/day for 8 weeks lowered TSH and raised T3/T4 in subclinical hypothyroidism [2]. A separate 2024 case report describes a healthy man developing thyroiditis with thyrotoxicosis after 2 months, resolving on discontinuation [4]. [2] - Pregnancy
Pregnancy safety is disputed in the literature, per NIH ODS's 2025 review [2].
Denmark's 2020 risk assessment and a 2000 American Herbal Pharmacopoeia monograph reach different conclusions. Read this as unresolved, not as clearance. [2] - Label accuracy
What's in the bottle may not match the label. Independent HPLC-MS testing of 19 commercial capsule products found none matched their stated withanolide content [8].
Some measured over 30 times lower than claimed. That makes every dose figure on this page approximate in practice. [8]
Food Sources
None. Ashwagandha isn't part of normal dietary intake and has no food sources in the ordinary sense — it comes from one specific plant grown for medicinal use, not as a food crop [1].
India's FSSAI restricts food and nutraceutical products to roots and root extracts only; leaves are prohibited in any form [10].
Best Time to Take
No trial has directly compared morning versus evening dosing, so there is no evidence-backed best time [2].
Where protocols do specify timing, the pattern is a split dose. A 30-day trial used 350 mg morning and 350 mg evening [11].
A UK long-COVID trial used 250 mg twice daily [12].
Common Questions
Is ashwagandha a drug?
No. In the US it's regulated as a dietary supplement, not a drug.
That means the FDA doesn't review or approve it before sale — the manufacturer is responsible for its own safety claims [1].
Can I take ashwagandha every day, long term?
Trials have mostly tested daily use for 6–12 weeks, some up to 90 days, and both NCCIH and NIH ODS call it well tolerated over that window [1].
Neither agency has evidence covering longer than about 3 months. That's a gap in the research, not a clean bill of health.
How long does it take to start working?
Most trials ran 6 to 12 weeks before measuring anything [2].
Sleep benefits specifically were more pronounced after at least 8 weeks. Nothing here supports expecting an effect in days.
Does it make you sleepy or give you energy?
Both have been reported, and it appears to vary by person and by study.
Drowsiness is listed among the common mild side effects in government safety reviews [1].
Does ashwagandha cause weight gain or weight loss?
There's no well-established effect either way.
One placebo-controlled trial of 52 adults under chronic stress, at 300 mg/day for 8 weeks, reported a favourable effect on weight management alongside its stress findings [13]. That's a single small trial.
Sources
- NCCIH — Ashwagandha: Usefulness and Safety — nccih.nih.gov. https://www.nccih.nih.gov/health/ashwagandha (date unknown)
- Office of Dietary Supplements - Ashwagandha: Is it helpful for stress, anxiety, or sleep? — ods.od.nih.gov. https://ods.od.nih.gov/factsheets/Ashwagandha-HealthProfessional/ (date unknown)
- Philips et al., Hepatology Communications — pmc.ncbi.nlm.nih.gov. https://pmc.ncbi.nlm.nih.gov/articles/PMC10531359 (2023-09-26)
- Hayashi et al., Cureus — pmc.ncbi.nlm.nih.gov. https://pmc.ncbi.nlm.nih.gov/articles/PMC10981964/ (2024-02-29)
- Marta et al., International Journal of Environmental Research and Public Health — mdpi.com. https://www.mdpi.com/1660-4601/20/5/3921 (2022-12-31)
- Therapeutic Goods Administration (TGA) — Withania somnifera (Ashwagandha) and very rare risk of liver injury — tga.gov.au. https://www.tga.gov.au/news/safety-updates/withania-somnifera-ashwagandha-and-very-rare-risk-liver-injury (2026-07-07)
- Therapeutic Goods Administration (TGA) — Medicines containing Withania somnifera (Withania, Ashwagandha) — tga.gov.au. https://www.tga.gov.au/safety/safety-monitoring-and-information/safety-alerts/medicines-containing-withania-somnifera-withania-ashwagandha (2024-02-21)
- Zellner et al., ELECTROPHORESIS — analyticalsciencejournals.onlinelibrary.wiley.com. https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/elps.202400188 (2025-02-28)
- Bonilla et al., Journal of Functional Morphology and Kinesiology — pmc.ncbi.nlm.nih.gov. https://pmc.ncbi.nlm.nih.gov/articles/PMC8006238 (2021-02-10)
- https://fssai.gov.in/upload/advisories/2026/04/69e0d84fcac2fAdvisory%20on%20non%20use%20of%20ashwagandha%20leaves%20in%20crude%20or%20extract%20or%20any%20other%20form%20in%20food%20products-%20reg.pdf (date unknown)
- ClinicalTrials.gov — clinicaltrials.gov. https://clinicaltrials.gov/study/NCT05430685 (date unknown)
- https://www.isrctn.com/editorial/retrieveFile/9ed45080-c47f-443e-9d59-6c40abed8b81/42176 (date unknown)
- Wiciński et al., Nutrients — pmc.ncbi.nlm.nih.gov. https://pmc.ncbi.nlm.nih.gov/articles/PMC12252077 (2025-06-26)