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Nootropics

Ashwagandha

A traditional botanical with small short-term stress and sleep trials, substantial product variation, and uncommon liver and thyroid risks.

Emerging
Evidence rating
Evidence review

What the evidence says

Ashwagandha products are root or root-and-leaf extracts of Withania somnifera, often standardized to different withanolide levels. A result from one proprietary extract cannot establish the dose, composition, or effect of another powder, gummy, or blend.[1][2]

A 2024 meta-analysis of nine randomized trials and 558 participants found improvements in perceived stress, anxiety scales, and cortisol. Another review of anxiety and insomnia included only five trials and 254 participants and reported extremely high heterogeneity, making the average effect uncertain.[2][3]

A broader 2025 review of 14 studies also found small-study and outlier sensitivity. NCCIH concludes that some preparations may help stress or insomnia over the short term, while evidence for anxiety and many other promoted uses remains unclear.[4][1]

Drowsiness, nausea, loose stools, and stomach upset occur. Rare clinically apparent liver injury has been reported, and ashwagandha may affect thyroid function. NCCIH advises avoidance during pregnancy and breastfeeding and cautions people with thyroid or autoimmune disease, upcoming surgery, or medicines for diabetes, blood pressure, sedation, seizures, immunity, or thyroid function.[5][1]

Potential benefits

  • May reduce perceived stress over roughly six to twelve weeks in some adults.[2]
  • May produce a small improvement in sleep measures with selected extracts.[3][1]

Side effects and cautions

  • Can cause drowsiness, nausea, diarrhea, vomiting, or abdominal discomfort.[1]
  • Rare liver injury and thyroid effects are possible; pregnancy and breastfeeding use should be avoided.[5][1]
How we scored it

Evidence breakdown

Meta-analyses suggest reduced perceived stress and small sleep improvements, but trials are short, heterogeneous, often industry-linked, and use noninterchangeable extracts.

Clinical relevanceModerate

Studies measure validated stress, anxiety, and sleep scales but not long-term function.

Study qualityLow

Samples are small and heterogeneous, with high inconsistency and extract-specific results.

Safety dataLow

Short-term tolerability is described, while long-term, reproductive, hepatic, and thyroid risks need better definition.

References

Full source list

  1. Ashwagandha: Usefulness and Safety

    National Center for Complementary and Integrative Health · 2025

  2. Effects of Ashwagandha supplementation on stress and anxiety: a systematic review and meta-analysis

    Nutrients · 2024

  3. Effect of Ashwagandha extract on anxiety and insomnia: a systematic review and meta-analysis

    Journal of Functional Foods · 2024

  4. Ashwagandha for mental health conditions: a systematic review and meta-analysis of randomized controlled trials

    Psychiatry Research · 2025

  5. Ashwagandha

    LiverTox, National Institute of Diabetes and Digestive and Kidney Diseases · 2024