Evidence-based summary of human clinical trials for Ashwagandha (Withania somnifera), covering stress, anxiety, cortisol, testosterone, and athletic performance outcomes.

This page summarizes peer-reviewed human clinical trials investigating the effects of ashwagandha (Withania somnifera).

Quick Answer

Ashwagandha has been evaluated in numerous randomized controlled trials investigating stress, anxiety, cortisol regulation, and physical performance outcomes. The strongest evidence supports its use for stress and anxiety, while research on testosterone, sleep quality, and athletic performance remains promising but somewhat more variable across study designs and populations.

The studies summarized below represent selected human clinical trials frequently cited in the scientific literature.

Mechanism Overview

Ashwagandha's primary bioactive compounds are withanolides (steroidal lactones), particularly withaferin A and withanolide D. These compounds are commonly discussed in relation to hypothalamic-pituitary-adrenal (HPA) axis modulation, inflammatory signaling, and neurotransmitter-related pathways.

HPA-axis regulation is often cited as one explanation for observed stress and cortisol effects
GABAergic and serotonergic pathways are frequently discussed in the literature
Inflammatory markers such as NF-κB, IL-6, and TNF-α are often referenced in mechanistic discussions
Mitochondrial and energy-related mechanisms are sometimes proposed in performance-related studies

Standardization matters: KSM-66 (root extract) and Sensoril (root + leaf extract) are among the most commonly studied commercial extract forms.

Human Clinical Trials Summary

Stress & Anxiety Reduction

Study	Design	Dose	Duration	Key Findings	PMID
Chandrasekhar et al., 2012	RCT, n=64	300mg KSM-66 2x/day	60 days	Reduced anxiety scores and serum cortisol versus placebo in chronically stressed adults.	23439798
Lopresti et al., 2019	RCT, n=60	240mg daily (Shoden)	60 days	Reported reductions in stress-related outcome measures and cortisol in the active-treatment group.	30854916
Salve et al., 2019	RCT, n=60	125mg, 250mg, or 600mg/day	8 weeks	All dose groups showed improvement in perceived stress scores, with stronger effects at higher doses.	32021735
Auddy et al., 2008	RCT, n=98	125–500mg Sensoril	60 days	Reported dose-related improvements in stress-related measures and serum cortisol.	18786858

Testosterone & Male Reproductive Health

Study	Design	Dose	Duration	Key Findings	PMID
Wankhede et al., 2015	RCT, n=57	300mg KSM-66 2x/day	8 weeks	Study reported improvements in strength and recovery, with testosterone-related changes also discussed.	26609282
Ahmad et al., 2010	Prospective, n=75	5g root powder/day	3 months	Reported improvements in semen-related parameters in infertile men.	19501822
Lopresti et al., 2019	RCT, n=43	600mg/day	8 weeks	Study discussed endocrine-related changes in overweight men, including testosterone-related markers.	30854916

Athletic Performance & Body Composition

Study	Design	Dose	Duration	Key Findings	PMID
Wankhede et al., 2015	RCT, n=57	300mg KSM-66 2x/day	8 weeks	Reported greater gains in strength and recovery outcomes in the active group.	26609282
Shenoy et al., 2012	RCT, n=40	500mg aqueous extract 2x/day	8 weeks	Reported improvement in cardiorespiratory endurance measures.	23125505
Ziegenfuss et al., 2018	RCT, n=50	300mg Sensoril 2x/day	12 weeks	Reported improvements in some recovery and performance-related measures in trained participants.	29520932

Sleep Quality

Study	Design	Dose	Duration	Key Findings	PMID
Langade et al., 2019	RCT, n=60	300mg KSM-66 2x/day	10 weeks	Reported improvements in sleep quality and sleep onset measures versus placebo.	31728244
Deshpande et al., 2020	RCT, n=150	120mg Shoden	6 weeks	Study reported improvements in sleep-related measures in the active-treatment group.	32540634

Dosages Used in Studies

KSM-66 (Root Extract)

Stress/anxiety studies commonly used 300mg 2x/day
Sleep-related studies often used similar daily totals
Performance-related studies also frequently used divided dosing

Sensoril (Root + Leaf)

Stress-related studies used lower to moderate daily doses
Some performance-related studies used divided daily dosing

Shoden / High-Withanolide Extracts

Sleep/stress studies used lower total daily doses

Unstandardized Preparations

Root powder and aqueous extracts have also been studied

Safety & Contraindications

Ashwagandha is generally well tolerated in many clinical studies, though tolerability can vary by dose, extract type, and individual health context.

Common side effects: Mild gastrointestinal discomfort, drowsiness, or digestive upset
Clinical cautions: Thyroid-related effects and medication interactions are sometimes discussed in the literature
Pregnancy / autoimmune context: Extra caution is commonly advised

Note: Rare case reports have discussed possible liver-related adverse events. People with liver conditions or complex medical histories should consult a qualified healthcare professional.

Evidence Summary

Stress / Anxiety: Strong evidence (Grade A−) — Multiple randomized trials support benefit in stress-related outcomes.
Sleep Quality: Moderate evidence (Grade B) — Controlled trials suggest potential benefit, though not all extracts and populations are identical.
Athletic Performance: Moderate evidence (Grade B) — Some trials suggest improvements in strength, recovery, or endurance-related outcomes.
Testosterone / Male Reproductive Health: Moderate evidence (Grade B−) — Findings are promising but should be interpreted cautiously across populations and endpoints.
Cognitive / Broader Health Outcomes: Preliminary evidence (Grade C) — More rigorous replication is needed.

References

Chandrasekhar K, Kapoor J, Anishetty S. 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. Indian J Psychol Med. 2012;34(3):255-262. PMID: 23439798
Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract. Medicine (Baltimore). 2019;98(37):e17186. PMID: 30854916
Salve J, Pate S, Debnath K, Langade D. Adaptogenic and Anxiolytic Effects of Ashwagandha Root Extract in Healthy Adults. Cureus. 2019;11(12):e6466. PMID: 32021735
Wankhede S, Langade D, Joshi K, et al. Examining the effect of Withania somnifera supplementation on muscle strength and recovery. J Int Soc Sports Nutr. 2015;12:43. PMID: 26609282
Ahmad MK, Mahdi AA, Shukla KK, et al. Withania somnifera improves semen quality by regulating reproductive hormone levels and oxidative stress. Fertil Steril. 2010;94(3):989-996. PMID: 19501822
Shenoy S, Chaskar U, Sandhu JS, Paadhi MM. Effects of eight-week supplementation of Ashwagandha on cardiorespiratory endurance. J Ayurveda Integr Med. 2012;3(3):111-114. PMID: 23125505
Langade D, Kanchi S, Salve J, et al. Efficacy and Safety of Ashwagandha (Withania somnifera) Root Extract in Insomnia and Anxiety. Cureus. 2019;11(9):e5797. PMID: 31728244
Ziegenfuss TN, Kedia AW, Sandrock JE, et al. Effects of an Aqueous Extract of Withania somnifera on Strength Training Adaptations and Recovery. Nutrients. 2018;10(11):1807. PMID: 29520932

Last updated: March 2026. This page summarizes published peer-reviewed research and is not medical advice. Consult a healthcare provider before starting any supplement.

Ashwagandha Clinical Studies