Ashwagandha (Withania somnifera) is an herb used for centuries in Ayurvedic medicine and now appears in a large share of men’s testosterone and stress formulas. Unlike many trendy ingredients, it has a reasonable number of human trials behind it. Here is what they show, and where the hype goes further than the evidence.
Testosterone
Several small randomized, placebo-controlled trials have measured testosterone in men taking ashwagandha root extract:
- In young men doing resistance training, 8 weeks of ashwagandha (around 300 mg twice daily) produced greater gains in strength and muscle size than placebo, along with a larger rise in testosterone.
- In overweight and middle-aged men, trials of 8 to 16 weeks reported modest increases in testosterone and DHEA-S compared with placebo.
Bottom line: the direction of the evidence is positive, but the studies are small, several were funded by extract manufacturers, and the increases are modest. Ashwagandha is not a replacement for medical treatment of low testosterone.
Strength and training
This is one of ashwagandha’s better-supported uses. Across several trials in men who lift, ashwagandha groups gained somewhat more strength than placebo groups over 8 to 12 weeks. The effect is meaningful but not dramatic, and training consistency matters far more.
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Stress and sleep
Many trials in adults report lower perceived stress scores and lower cortisol, and some report better sleep quality, particularly in people with high stress or insomnia. Because poor sleep and chronic stress both suppress testosterone, this may be part of how ashwagandha helps men.
Doses and extract types
- Most trials used root extracts at 300–600 mg per day, often split into two doses.
- Well-studied branded extracts include KSM-66 and Sensoril. Standardized extracts list their withanolide content, which helps compare products.
- Effects in studies appeared after 8 weeks or more.
Safety and who should avoid it
Ashwagandha is well tolerated by most healthy adults in the short term, but there are real cautions:
- Liver: rare cases of liver injury have been reported. Stop and see a doctor if you notice yellowing skin, dark urine or abdominal pain.
- Thyroid: it may raise thyroid hormone levels. Avoid it if you have a thyroid condition unless your doctor approves.
- Medications: it may interact with sedatives, thyroid medication, immunosuppressants and diabetes or blood pressure medication.
- Autoimmune conditions: it may stimulate the immune system.
Some European countries have restricted or reviewed ashwagandha products, reflecting these concerns. Use it for defined periods and tell your doctor you are taking it.
How to choose an ashwagandha supplement
- Look for a standardized root extract with the dose in milligrams
- Check the dose matches the 300–600 mg range used in studies
- Prefer products tested by a third party
- Avoid proprietary blends that hide how much ashwagandha is actually in the product
Many testosterone-support formulas include ashwagandha. Compare them in our testosterone supplement guide.
Does ashwagandha increase testosterone?
Small trials report modest increases, mostly in men training with weights or in overweight and middle-aged men. The effect is smaller than marketing suggests.
How long does ashwagandha take to work?
Most studies measured results after 8 to 12 weeks of daily use.
Is it safe to take ashwagandha every day?
Short-term daily use appears safe for most healthy adults, but rare liver injury has been reported. Avoid it with thyroid conditions and check with your doctor if you take medication.