Ashwagandha (Withania somnifera), also called Indian ginseng or winter cherry, is an evergreen shrub whose root has long been used in Ayurvedic medicine and is classed as an "adaptogen." Its main studied compounds are steroidal lactones called withanolides. It is sold in the US as a dietary supplement (commonly standardized root extracts branded KSM-66, Sensoril, or Shoden) and is NOT reviewed or approved by the FDA before sale.
Online and in brand copy, ashwagandha is marketed as a near-cure-all: "crush cortisol," erase anxiety, fix sleep, spike testosterone, build muscle, sharpen focus. Government science is far more restrained. NIH's NCCIH states plainly that many trials exist but "many of the studies have had small sample sizes and have used a variety of ashwagandha preparations," most run in India within a traditional-medicine setting and often with industry involvement. Supplements are not FDA-approved and cannot legally claim to treat or cure any disease; independent testing has repeatedly found supplement contents don't always match the label. The honest picture is promising-but-weak evidence for a couple of uses, not proof.
NCCIH: 'some ashwagandha preparations may be effective for insomnia and stress.' NIH ODS summarizes multiple small RCTs and a 2021 systematic review showing reduced self-reported stress vs placebo, with benefit often greater at 500-600 mg/day; a 2022 Phytother Res meta-analysis (12 RCTs, 1,002 participants) found a significant stress reduction but rated the certainty of evidence LOW. Trials are small, short (6-12 weeks), heterogeneous, and heavily industry-connected.
NCCIH's verdict: 'evidence is unclear about its effects on anxiety.' Some pooled analyses show reduced anxiety scores, but results conflict across trials and the 2022 meta-analysis rated certainty LOW. Not a validated treatment for a diagnosed anxiety disorder.
Several trials summarized by NIH ODS reported lower serum or salivary cortisol vs placebo. This is a surrogate lab biomarker, not a clinical outcome; a lower cortisol number does not by itself prove feeling better or being healthier.
A 2021 PLoS One systematic review/meta-analysis (Cheah et al., 5 RCTs, ~400 adults) found a 'small but significant effect on overall sleep' (SMD -0.59), most prominent in adults diagnosed with insomnia, at doses >=600 mg/day for >=8 weeks; no significant effect on quality of life. NCCIH agrees preparations 'may be effective for insomnia.' A modest help, strongest in true insomnia, not a sleep cure.
NCCIH: only 'some limited evidence' that 2-4 months of use 'may increase testosterone levels and sperm quality,' and separately 'not enough evidence' for athletic performance. A few small resistance-training RCTs in men (e.g., Wankhede 2015, n=57) reported greater strength, muscle size, and testosterone, but these are small, short, mostly in men, and industry-adjacent. A preliminary signal, not established; do not treat it as a testosterone or muscle booster.
NCCIH: 'There isn't enough evidence to determine if ashwagandha is helpful for any other health conditions,' and specifically not enough high-quality evidence for COVID-19.
No official or FDA-set dose. In trials, standardized root extract was commonly used at roughly 250-600 mg/day, often 300 mg twice daily, for about 8-12 weeks; stress and sleep benefits tended to appear around 500-600 mg/day (sleep effects strongest at >=600 mg/day for >=8 weeks). Products differ by extract type, plant part (root vs leaf), and withanolide standardization, so doses are NOT interchangeable between brands and a "600 mg" of one is not equivalent to another. More is not proven better, and long-term dosing has not been studied.
Short-term use (up to about 3 months) is generally well tolerated in trials; long-term safety is unknown. Common, usually mild effects: drowsiness/sedation, stomach upset, nausea, diarrhea, vomiting. RARE BUT SERIOUS — LIVER INJURY: NIH LiverTox assigns a likelihood score of "B" (a likely cause of clinically apparent liver injury); documented cases typically appear 2-12 weeks after starting with jaundice, pruritus (itching), nausea, and dark urine, usually resolving 1-4 months after stopping, but rare fatal cases and liver transplant have been reported, especially with pre-existing liver disease. Because commercial products can be mislabeled or adulterated, contamination is a real concern. Stop and seek care for yellowing skin/eyes, dark urine, pale stools, severe itching, or right-upper-abdomen pain. AVOID: pregnancy (may stimulate uterine activity) and breastfeeding; existing liver disease/cirrhosis; thyroid disease (may increase thyroid hormone activity/destabilize control); autoimmune conditions (may stimulate immune activity); hormone-sensitive prostate cancer (may raise testosterone); before surgery (sedative; many clinicians advise stopping ~2 weeks prior). DRUG INTERACTIONS — tell your prescriber first: diabetes medicines, blood pressure medicines, sedatives/benzodiazepines and sleep aids, anti-seizure medicines, immunosuppressants, and thyroid hormone medication.
Ashwagandha is one of the better-studied supplements for stress and sleep, but "better-studied" still means small, short, low-certainty, mostly industry-linked trials — not the standard of an approved drug. A healthy adult trying it for short-term stress or sleep should expect a modest, not dramatic, effect at roughly 300-600 mg/day of a standardized root extract for a few weeks. Anxiety evidence is unclear; the testosterone/muscle claims are preliminary; the cure-all marketing is unsupported. The real trade-off is a rare but genuine risk of liver injury, plus several groups (pregnancy/breastfeeding, thyroid disease, liver disease, autoimmune conditions, hormone-sensitive prostate cancer, pre-surgery) who should not take it. Talk to your clinician or pharmacist first, buy third-party-tested products, and stop immediately at any sign of liver trouble. This is not medical advice or a promise of results.
General information, not medical advice. Dietary supplements are not FDA-approved to treat, cure, or prevent any disease, and quality/purity vary by brand. Talk to your clinician or pharmacist before starting one — especially if you’re pregnant, breastfeeding, or take other medicines.