Ashwagandha for Stress: What the Trial Evidence Actually Supports

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What the published trials show

• Stress and anxiety: An 8-week (60-day) RCT of 300 mg twice daily (600 mg/day) of KSM-66 extract produced a 44.0% reduction in PSS-10 (Perceived Stress Scale) scores vs. a 5.5% reduction in the placebo group Chandrasekhar 2012.
• Cortisol: Small trials report lower cortisol in chronically stressed adults over about 8 weeks, with the largest drops where baseline cortisol was elevated and smaller changes in adults already in the normal range.
• Sleep quality: Small trials report modest improvements in subjective sleep scores at 8-12 weeks. Persistent insomnia is worth raising with a clinician rather than self-treating.
• Resistance training adaptation: Significant gains in strength and lean mass in previously untrained young men over 8 weeks (bench press +46.0 kg vs. +26.4 kg placebo) Wankhede 2015.
• Testosterone: Some trials show small increases in adults with stress-related low testosterone, returning toward (not exceeding) normal range. The dramatic claims around testosterone are overstated.
• Cognitive performance: A few small trials report modest improvements in memory and executive function in older adults; the evidence is preliminary.

“A high-concentration full-spectrum Ashwagandha root extract safely and effectively improves an individual’s resistance towards stress and thereby improves self-assessed quality of life.”

— Chandrasekhar et al., Indian J Psychol Med, 2012 view source

What the trials used (not a prescription)

• Doses studied: most trials used 300-600 mg daily of a standardised root extract (KSM-66 and Sensoril are the most-studied; both are standardised for withanolide content).
• Duration: the trials ran 8-12 weeks, and effects built gradually.
• Long-term use: few trials ran beyond 12 weeks, so long-term safety data are limited.
• Your situation: whether ashwagandha is appropriate for you, and how much, is a question for your pharmacist or clinician — particularly with the cautions below.

Cautions and contraindications

• Autoimmune disease. Ashwagandha may stimulate certain immune pathways. Adults with autoimmune thyroid disease (Hashimoto’s), rheumatoid arthritis, lupus, multiple sclerosis should not start without medical guidance.
• Pregnancy and lactation. Not recommended — insufficient safety data.
• Thyroid medication. Ashwagandha can raise thyroid hormone levels. Anyone on levothyroxine or other thyroid treatment should talk to their doctor before starting, as their levels may need checking.
• Sedative medications. Benzodiazepines, anticonvulsants, sleep medications — ashwagandha can amplify sedative effects.
• Surgery. Tell your surgical team if you take it; stopping about 2 weeks before a scheduled procedure is commonly advised because of theoretical anaesthesia interactions.
• Liver. Rare cases of liver injury have been reported. Stop and seek medical care if jaundice, dark urine or unusual fatigue appear, and check with a clinician first if you have liver disease.
• Standard prescription medications. Discuss with a pharmacist before starting, especially if you take multiple medications.

Practical takeaways

• Ashwagandha has modest published evidence for stress, anxiety scores, sleep quality, and resistance-training adaptation — not evidence that it treats an anxiety disorder or insomnia.
• The effect sizes are modest, not dramatic. In the trials, daily use of standardised extracts produced measurable but small improvements over 8-12 weeks.
• Doses studied: 300-600 mg of standardised root extract (KSM-66 or Sensoril) daily for 8-12 weeks. Ask a pharmacist or clinician whether it is appropriate for you.
• Contraindications matter: autoimmune disease, pregnancy, thyroid medication, sedatives. Talk to a doctor or pharmacist.
• Marketing claims around testosterone, immune system, and dramatic performance gains overstate the evidence.

References