Ashwagandha
PromisingAdaptogenic herb for stress reduction and hormonal balance.
Not medical advice
Nutripedia summarises published peer-reviewed research. This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before taking any supplement.
Ashwagandha (Withania somnifera) is a traditional Ayurvedic adaptogen with growing clinical support for reducing cortisol levels, improving stress resilience, and supporting testosterone and thyroid function.
Promising evidence for stress and cortisol reduction. Some support for testosterone in men and exercise performance. Long-term safety data is limited.
Evidence Database
Click any row to explore the studies behind each health outcome. Grades reflect the volume and quality of published research, not a recommendation.
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General Information
Dosage (Evidence-Reported)
These figures reflect what clinical studies used — not personalised recommendations.
Safety Notes
- May interact with thyroid medications
- Not recommended during pregnancy
- Rare reports of liver injury at high doses — use standardised extracts
- Long-term safety data beyond 3 months is limited
Key Benefits
- Reduces perceived stress and cortisol levels
- May support healthy testosterone levels in men
- Could improve sleep quality
- Potential exercise performance benefits
Quick Facts
Nutripedia is an educational resource. Content is sourced from peer-reviewed studies and does not constitute medical advice. Consult a healthcare professional before starting any supplement.
The Evidence
17 peer-reviewed papers, updated yesterday
8 meta-analyses · 7 RCTs · 2 case studies
Effects of ashwagandha (Withania somnifera) on mental health in adults: A systematic review and dose-response meta-analysis of randomized controlled trials
Alsanie SA, Alhodieb FS, Askarpour M
Complementary Therapies in Medicine
Dose-response meta-analysis of 22 RCTs (1,391 participants) demonstrated ashwagandha significantly alleviates stress, anxiety, and depression. Lower doses (≤500 mg/day) combined with longer treatment periods (>8 weeks) showed superior outcomes. Supports ashwagandha as a clinically relevant adaptogen pending further high-quality trials.
Effects of Ashwagandha Supplements on Cortisol, Stress, and Anxiety Levels in Adults: A Systematic Review and Meta-Analysis
Bachour G, Samir A, Haddad S et al.
BJPsych Open
Meta-analysis of 15 RCTs (873 participants) found ashwagandha produced statistically significant reductions in serum cortisol, Perceived Stress Scale scores, and HAM-A scores vs placebo. No significant improvement in quality of life was observed. Concluded safe and effective for stress and anxiety reduction in adults.
The effect of Withania somnifera (Ashwagandha) on mental health symptoms in individuals with mental disorders: systematic review and meta-analysis
Marchi M, Grenzi P, Travascio A et al.
BJPsych Open
Systematic review and meta-analysis of 14 RCTs (360 treatment, 353 controls) found evidence supporting ashwagandha efficacy for anxiety symptoms in individuals with mental disorders. Promising signals for depression and insomnia. Median effective dose was 600 mg/day over 8 weeks, with good tolerability. Larger trials needed.
Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis
Arumugam V, Vijayakumar V, Balakrishnan A et al.
Explore (NY)
Analysis of 9 RCTs (558 patients) found ashwagandha formulations produced statistically significant reductions in perceived stress, anxiety scale scores, and serum cortisol levels vs placebo. Adverse effects were mostly mild. Supports ashwagandha as an effective and tolerable adaptogen for stress and anxiety management in adults.
Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis
Akhgarjand C, Asoudeh F, Bagheri A et al.
Phytotherapy Research
Meta-analysis of 12 RCTs (1,002 participants) found ashwagandha significantly reduced anxiety and stress vs placebo. Certainty of evidence was rated low, warranting further high-quality studies. Doses of 300-600 mg/day appeared optimal for stress reduction; higher doses explored for anxiety.
Ashwagandha as a Unique Cause of Thyrotoxicosis Presenting With Supraventricular Tachycardia
Kamal HI, Patel K, Brdak A et al.
Cureus
Case report of a 73-year-old woman who developed thyrotoxicosis and supraventricular tachycardia after two years of ashwagandha self-supplementation for hypothyroid symptoms. Symptoms fully resolved on discontinuation, establishing temporal causality. Highlights clinically significant thyroid interaction risk, particularly in patients with pre-existing thyroid conditions.
Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis
Cheah KL, Norhayati MN, Yaacob LH et al.
PLOS ONE
Meta-analysis of 5 RCTs (400 participants) found ashwagandha extract produced a small but statistically significant improvement in overall sleep quality. Effects were stronger in adults with diagnosed insomnia, at doses ≥600 mg/day, and treatment ≥8 weeks. Mental alertness and anxiety also improved. Long-term safety data remain limited.
Effects of Ashwagandha (Withania somnifera) on Physical Performance: Systematic Review and Bayesian Meta-Analysis
Bonilla DA, Moreno Y, Gho C et al.
Journal of Functional Morphology and Kinesiology
Bayesian meta-analysis of 12 RCTs found ashwagandha supplementation superior to placebo for strength/power (medium effect), cardiorespiratory fitness (very large effect), and fatigue/recovery (large effect). VO2max and haemoglobin increased significantly at doses of 330-1000 mg/day over 8-24 weeks. Supports use for physical performance enhancement.
Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients: A double-blind, randomized, parallel-group, placebo-controlled study
Langade D, Thakare V, Kanchi S et al.
Journal of Ethnopharmacology
8-week RCT of ashwagandha root extract (KSM-66, 600 mg/day) in 80 adults (healthy and insomnia patients) showed significant improvements in sleep onset latency, sleep efficiency, total sleep time, and anxiety on waking vs placebo. Benefits were greater in insomnia patients. Well-tolerated across all participants.
Effects of Ashwagandha (Withania somnifera) on VO2max: A Systematic Review and Meta-Analysis
Pérez-Gómez J, Villafaina S, Adsuar JC et al.
Nutrients
Meta-analysis of 4 RCTs (142 participants) found ashwagandha supplementation significantly improved VO2max by a mean of 3.00 mL/kg/min (95% CI: 0.18-5.82, p=0.04) in both athletes and non-athletes. Evidence quality was rated low due to small sample sizes and high heterogeneity (I²=84%). Further adequately powered RCTs recommended.
Liver Injury due to Ashwagandha. A Case Series from Iceland and the U.S. Drug-Induced Liver Injury Network
Björnsson HK, Björnsson ES, Avula B et al.
Liver International
Case series of 5 patients (3 Iceland, 2 US DILIN) demonstrated ashwagandha has hepatotoxic potential. Liver injury presented as cholestatic or mixed pattern with jaundice and pruritus, onset 2-12 weeks after starting supplementation. All cases were self-limited with liver tests normalising within 1-5 months. No cases progressed to hepatic failure.
An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study
Lopresti AL, Smith SJ, Malvi H et al.
Medicine (Baltimore)
60-day RCT (n=60) of 240 mg Shoden ashwagandha extract found statistically significant reductions in HAM-A anxiety scores and morning serum cortisol vs placebo. DHEA-S also reduced. Proposed mechanism is modulation of the HPA axis. Well-tolerated with no serious adverse events. Supports use in stressed healthy adults.
A Randomized, Double-Blind, Placebo-Controlled, Crossover Study Examining the Hormonal and Vitality Effects of Ashwagandha (Withania somnifera) in Aging, Overweight Males
Lopresti AL, Drummond PD, Smith SJ
American Journal of Men's Health
16-week crossover RCT (n=57) found 8 weeks of ashwagandha extract significantly increased salivary DHEA-S and testosterone in males aged 40-70, but did not significantly affect cortisol, estradiol, fatigue, or sexual well-being. Hormonal elevations did not translate clearly to symptomatic benefit in this older overweight cohort.
Effects of an Aqueous Extract of Withania somnifera on Strength Training Adaptations and Recovery: The STAR Trial
Ziegenfuss TN, Kedia AW, Sandrock JE et al.
Nutrients
12-week RCT of Sensoril (500 mg aqueous ashwagandha extract, roots+leaves) in 38 recreationally active men found significantly greater squat (+19.1 vs +10.0 kg) and bench press (+12.8 vs +8.0 kg) 1-RM gains vs placebo, improved body composition, and enhanced recovery perceptions. Well tolerated clinically. Key Sensoril-specific performance RCT.
Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients: A Double-Blind, Randomized Placebo-Controlled Trial
Sharma AK, Basu I, Singh S
Journal of Alternative and Complementary Medicine
8-week pilot RCT (n=50) of 600 mg/day ashwagandha root extract in subclinical hypothyroid patients (TSH 4.5-10 μIU/L) found significant improvements in serum TSH, T3, and T4 vs placebo. Suggests ashwagandha may stimulate thyroid hormone synthesis. Clinicians should monitor thyroid function in patients on thyroid medications.
Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial
Wankhede S, Langade D, Joshi K et al.
Journal of the International Society of Sports Nutrition
8-week RCT of KSM-66 (300 mg twice daily) in 57 untrained males found significantly greater gains in bench-press and leg-extension strength, muscle size, testosterone (+96 vs +18 ng/dL, p=0.004), and reduced exercise-induced muscle damage vs placebo. Concludes ashwagandha supplementation is beneficial alongside resistance training.
A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults
Chandrasekhar K, Kapoor J, Anishetty S
Indian Journal of Psychological Medicine
64-participant, 60-day RCT of KSM-66 300 mg twice daily found significant reductions (p<0.0001) across all stress-assessment scales and substantially reduced serum cortisol vs placebo. Mild adverse effects comparable between groups. Concluded this full-spectrum root extract safely improves resistance to stress. Foundational KSM-66 RCT.