Ashwagandha may modestly increase testosterone in men, but the evidence is less definitive than supplement marketing suggests. Clinical trials have reported increases of roughly 15% in some male participants over 8 weeks, though even within those studies, the data has inconsistencies that make researchers cautious about the size of the effect. The herb likely works best as a supporting factor rather than a powerful hormonal intervention.
What the Clinical Trials Actually Show
The most-cited evidence comes from an 8-week randomized controlled trial of 50 healthy men (average age 35) who took 600 mg of a standardized root extract daily. The ashwagandha group showed improved sexual function scores and what appeared to be a 15% increase in serum testosterone compared to placebo. However, Examine, a widely respected independent research database, flagged an inconsistency: one of the study’s own figures actually suggested the opposite of what the text claimed, which casts some doubt on the testosterone finding specifically.
Other trials have found more consistent results in men dealing with infertility. Studies on men with low sperm counts have shown that ashwagandha can improve sperm count and motility while shifting reproductive hormone levels in a favorable direction. A 90-day study on male infertility reported significant improvements in both sperm quality and hormone profiles after three months of daily use. These fertility-focused studies tend to show clearer benefits, possibly because there’s more room for improvement when hormone levels start below optimal.
In women, the picture is different. One controlled trial found that testosterone levels increased in male participants but showed virtually no change in females. Ashwagandha did reduce cortisol (the body’s primary stress hormone) in both sexes, which points to a stress-related mechanism rather than a direct hormonal one.
How It Likely Works
Ashwagandha doesn’t act like a hormone replacement. Instead, it appears to create conditions that let your body produce testosterone more efficiently. The primary pathway involves stress reduction. Chronic stress keeps cortisol elevated, and high cortisol directly suppresses the signaling chain between your brain and testes that drives testosterone production. By lowering cortisol, ashwagandha may remove a hormonal bottleneck.
Beyond cortisol, researchers believe ashwagandha’s active compounds (called withanolides) help reduce inflammation, oxidative stress, and insulin resistance. All three of these factors can independently drag testosterone levels down. This means the herb is more likely to help men whose testosterone is being suppressed by lifestyle factors like poor sleep, chronic stress, or metabolic issues than men who already have well-optimized health habits. If your testosterone is low because of a primary medical condition, ashwagandha alone is unlikely to fix the problem.
Dosage and Timeline
Most clinical trials showing hormonal effects have used 200 to 600 mg per day of a standardized extract. The extract type matters: KSM-66, standardized to at least 5% withanolides, is the most frequently studied formulation. Lower-quality products with unstandardized root powder may not deliver comparable results.
Don’t expect overnight changes. Some effects on mood and stress may appear within 2 to 4 weeks, but measurable hormonal shifts typically require 8 to 12 weeks of consistent daily use. The fertility studies that showed the strongest results ran for a full 90 days. If you’re going to try it, commit to at least two months before evaluating whether it’s working for you.
Who Should Avoid It
Ashwagandha increases levels of thyroid hormones T3 and T4, likely as a downstream effect of its stress-modulating properties. For most people, this is insignificant. But if you have an overactive thyroid (hyperthyroidism), ashwagandha can push thyroid hormone levels dangerously higher. People taking thyroid medications of any kind, whether for an overactive or underactive thyroid, should avoid mixing them with ashwagandha because the herb can interfere with the medication’s ability to regulate hormone levels predictably.
Gastrointestinal discomfort is the most commonly reported side effect in otherwise healthy people, and it tends to be mild. Taking ashwagandha with food usually helps.
Putting It in Perspective
Ashwagandha is not a testosterone therapy substitute. The potential 15% increase seen in trials, even if fully accurate, would take a man with a testosterone level of 400 ng/dL to roughly 460 ng/dL. That’s a meaningful nudge for someone sitting near the lower end of normal, but it won’t transform clinically low testosterone into a healthy range. For context, resistance training alone can produce similar or larger acute hormonal shifts.
Where ashwagandha fits best is as one piece of a broader approach: adequate sleep, regular strength training, healthy body weight, and managed stress. If chronic stress is a major factor in your life and you suspect it’s dragging your hormones down, ashwagandha has reasonable evidence behind it as a supportive tool. If you’re looking for a supplement to dramatically raise testosterone on its own, the current research doesn’t support that expectation.