Ashwagandha, an herb used for centuries in traditional Indian medicine, has the strongest evidence in men for modestly raising testosterone, lowering cortisol-driven stress, and improving sperm quality. Several smaller but promising trials also point to gains in muscle strength, sleep, and sexual function. The picture is not all upside, though: reports of liver injury and thyroid disruption have emerged, and the supplement market’s loose quality controls add a layer of risk that the headlines rarely mention.
Testosterone and Hormonal Effects
The most-discussed claim about ashwagandha for men is that it boosts testosterone. Multiple randomized controlled trials support a real but moderate effect. In a crossover study of overweight men aged 40 to 70, ashwagandha supplementation raised testosterone by about 15% compared to placebo, along with an 18% bump in DHEA-S, a hormone precursor produced by the adrenal glands.1PubMed Central. A Randomized, Double-Blind, Placebo-Controlled, Crossover Study Examining the Hormonal and Vitality Effects of Ashwagandha (Withania somnifera) in Aging, Overweight Males A separate trial in young men doing resistance training found a larger jump of roughly 96 ng/dL in the ashwagandha group versus 18 ng/dL in the placebo group.2PubMed Central. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial
A stress-focused trial paints a slightly more cautious picture. Men taking ashwagandha saw about an 11% testosterone increase, which was individually significant compared to baseline but did not reach statistical significance when compared head-to-head with the placebo group.3PubMed Central. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract That matters: the effect seems real enough to show up repeatedly, but it is not enormous, and individual responses vary. Men starting with very low testosterone due to a medical condition should not expect ashwagandha to replace clinical treatment. For men with levels in the normal range, the nudge upward may contribute to some of the downstream benefits discussed below, but it is unlikely to produce dramatic, noticeable hormonal shifts on its own.
Fertility and Sperm Quality
The fertility data is where ashwagandha’s numbers look most striking, though the studies are small and mostly conducted in men who already had low sperm counts. A pilot study in men with clinically low sperm concentration found a 167% increase in sperm count, a 53% increase in semen volume, and a 57% improvement in sperm motility after 90 days of supplementation.4PubMed Central. Clinical Evaluation of the Spermatogenic Activity of the Root Extract of Ashwagandha (Withania somnifera) in Oligospermic Males: A Pilot Study Those percentages sound massive, but keep in mind the starting point: these men had very poor baseline numbers, so large relative jumps do not necessarily mean the final values reached outstanding levels.
A systematic review and meta-analysis pooling data from observational studies confirmed the general direction of these findings, reporting statistically significant improvements in semen volume, sperm concentration, and motility. Among men with normal sperm counts who were trying to conceive, about 14% achieved pregnancy during the study period.5Phytomedicine. Withania somnifera (Indian ginseng) in male infertility: An evidence-based systematic review and meta-analysis The review noted that only one randomized controlled trial was available at the time, so most of the pooled data came from before-and-after comparisons without a placebo group. That weakens the certainty somewhat, but the consistency of results across several studies is encouraging for men dealing with subfertility.
One proposed mechanism links back to cortisol. Chronic stress damages sperm quality through oxidative stress, and ashwagandha’s antioxidant and cortisol-lowering properties may be part of why sperm parameters improve. Researchers have also noted rises in luteinizing hormone, which signals the testes to produce testosterone and supports sperm development.5Phytomedicine. Withania somnifera (Indian ginseng) in male infertility: An evidence-based systematic review and meta-analysis
Stress and Cortisol
Ashwagandha is classified as an adaptogen, a loose category of herbs thought to help the body manage stress. The cortisol-lowering effect is one of the more consistently replicated findings. In a randomized, double-blind trial of stressed but otherwise healthy adults, those taking ashwagandha extract had significantly lower cortisol levels than the placebo group, along with lower perceived-stress scores, better sleep quality scores, and higher self-reported happiness.6PubMed Central. Efficacy and Safety of Ashwagandha Root Extract on Cognitive Functions in Healthy, Stressed Adults: A Randomized, Double-Blind, Placebo-Controlled Study
This stress-reduction angle is relevant to men specifically because chronically elevated cortisol can suppress testosterone production and impair sleep, libido, and recovery from exercise. It also contributes to visceral fat accumulation. So even if ashwagandha’s direct testosterone-raising effect is modest, the indirect benefit of keeping cortisol in check may amplify the practical results men care about.
Sleep Quality
Several trials have tested ashwagandha specifically for sleep, and a meta-analysis of five studies found it improved sleep quality, reduced the time it takes to fall asleep, increased total sleep time, and decreased the amount of time spent awake after initially falling asleep.7PLOS ONE. Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis These benefits appeared in both healthy volunteers and people with insomnia, though the effects were more pronounced in those who had trouble sleeping to begin with.8PubMed. 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
The meta-analysis authors rated the quality of evidence as low to moderate, which is common for herbal supplement research. Still, the consistency across studies makes this one of the better-supported claims. For men who lift weights or train regularly, improved sleep directly translates to better recovery and muscle growth, which may partly explain why the exercise studies show results beyond what the strength-training stimulus alone would predict.
Strength and Exercise Performance
If you exercise, ashwagandha may give you a slight edge. A systematic review using Bayesian analysis across multiple trials concluded that ashwagandha was more effective than placebo for improving variables related to physical performance, including strength, cardiorespiratory fitness, and fatigue recovery.9PubMed Central. Effects of Ashwagandha (Withania somnifera) on Physical Performance: Systematic Review and Bayesian Meta-Analysis An eight-week trial found significant improvements in bench press and leg press strength in both men and women taking the extract, along with greater gains in arm, chest, and thigh girth compared to placebo.10PubMed Central. Effects of Ashwagandha (Withania somnifera) standardized root extract on physical endurance and VO2max in healthy adults performing resistance training
The practical magnitude matters here. Ashwagandha is not going to replace consistent training, adequate protein, or proper sleep. Think of it as a potential minor accelerator rather than a game-changer. The combination of slightly higher testosterone, lower cortisol, and better sleep quality may contribute to an environment in which muscle recovery and adaptation happen a bit more efficiently.
Sexual Function
Beyond fertility and hormones, a few trials have looked at how men actually experience their sex lives. A randomized trial in healthy adult men found that those taking ashwagandha root extract for eight weeks reported a 40% improvement on a standardized male sexual function questionnaire, compared to 25% in the placebo group. The ashwagandha group also showed a 17% rise in serum testosterone.11PubMed Central. Effect of standardized root extract of ashwagandha Withania somnifera on well‐being and sexual performance in adult males: A randomized controlled trial A separate trial focusing specifically on sexual health domains found that eight weeks of ashwagandha improved orgasmic function, sexual desire, and overall satisfaction compared to placebo.12Journal of Ayurveda and Integrative Medicine. Efficacy and safety of eight-week therapy with Ashwagandha root extract in improvement of sexual health in healthy men
These results are worth some skepticism. Self-reported sexual function is heavily influenced by placebo effects and expectation, and the trials are small. But the consistency of the direction across multiple studies and the plausible biological underpinning (lower stress, higher testosterone, better sleep) make it a reasonable area for continued research.
Cognitive Benefits
A smaller body of evidence suggests ashwagandha may sharpen some aspects of mental performance, at least acutely. A study measuring cognitive function after a single dose found improvements in working memory and sustained attention. Participants taking ashwagandha maintained reaction times over several hours, while those on placebo showed signs of mental fatigue and slower responses.13PubMed Central. Effects of Acute Ashwagandha Ingestion on Cognitive Function The herb did not improve accuracy, though, suggesting it helps you stay alert rather than making you smarter in any deep sense. This is early-stage research, and the cognitive claims should be held much more loosely than the stress or fertility data.
Liver Injury
This is the risk that gets the least attention and arguably deserves the most. A growing number of case reports describe liver damage linked to ashwagandha use. A case series from Iceland and the U.S. Drug-Induced Liver Injury Network documented five patients who developed jaundice between two and twelve weeks after starting ashwagandha. Symptoms included nausea, itching, and abdominal discomfort. Liver function normalized within one to five months after stopping the supplement, but the episodes were prolonged and unpleasant.14PubMed Central. Ashwagandha-induced liver injury: A case series from Iceland and the US Drug-Induced Liver Injury Network
A separate case series from India confirmed additional cases and noted that the active compounds in ashwagandha, called withanolides, may cause irreversible binding to liver cell DNA as a possible mechanism of injury.15PubMed Central. Ashwagandha-induced liver injury—A case series from India and literature review A systematic review of all published case reports found that liver injury patterns include inflammation-dominant, bile-flow-blockage, or mixed types. Most patients recovered after stopping ashwagandha, but severe cases required intensive care, and at least one required a liver transplant.16The Egyptian Journal of Internal Medicine. Ashwagandha-induced liver injury: a systematic review of case reports
To be clear, these are rare events relative to how many people take ashwagandha. A 12-month observational safety study of standardized root extract reported only 18 mild adverse events, all of which resolved on their own.17PubMed Central. Safety of 12-Months Administration of Ashwagandha (Withania somnifera) Standardized Root Extract in Healthy Adults: A Prospective, Observational Study But “rare” is cold comfort if you are the one whose liver enzymes spike. If you use ashwagandha regularly and develop unexplained fatigue, dark urine, or yellowing skin, stop taking it and get your liver checked.
Thyroid Disruption
Ashwagandha can push thyroid hormone levels up, which is occasionally marketed as a benefit for sluggish thyroid function. The problem is that this effect is unpredictable and can overshoot. Case reports describe thyrotoxicosis, a condition where thyroid hormones run dangerously high. One involved a 73-year-old woman who had been self-treating hypothyroidism with ashwagandha for two years and developed a rapid heart rhythm along with lab values showing suppressed thyroid-stimulating hormone. Her symptoms resolved after she stopped the supplement.18PubMed Central. Ashwagandha as a Unique Cause of Thyrotoxicosis Presenting With Supraventricular Tachycardia
Thyrotoxicosis from ashwagandha has also been reported in previously healthy people with no thyroid problems at all. Because the condition can progress to a thyroid storm or eventually lead to permanent hypothyroidism, researchers have urged caution, especially for anyone already taking thyroid medication.19PubMed Central. Painless Thyroiditis by Withania somnifera (Ashwagandha) Men with diagnosed thyroid conditions or a family history of thyroid disease should discuss ashwagandha with a doctor before trying it.
Other Side Effects and Drug Interactions
Beyond the liver and thyroid issues, a critical review of both preclinical and clinical evidence flagged gastrointestinal side effects, immune hypersensitivity, and endocrine disruption as concerns with prolonged or high-dose use.20PubMed Central. Potential Adverse Effects of Ashwagandha: A Critical Review of Preclinical and Clinical Evidence Mild GI complaints like nausea or loose stools are the most commonly reported side effects in trials and are generally not serious.
The immune-modulation angle is worth knowing about. Animal studies suggest ashwagandha can suppress certain overactive immune responses, which sounds appealing for autoimmune conditions. But the clinical evidence in humans with autoimmune disease is almost nonexistent, and ramping up or suppressing immune activity in unpredictable ways could theoretically cause flares in susceptible people.21PubMed Central. Ashwagandha as an Adaptogenic Herb: A Comprehensive Review of Immunological and Neurological Effects Men on immunosuppressive drugs or with conditions like lupus or rheumatoid arthritis should be cautious.
Dosage and Duration
Most clinical trials used between 300 mg and 600 mg of a standardized root extract per day, typically split into two doses. Studies focused on exercise performance have sometimes used higher doses, up to about 1,250 mg daily. Benefits in most trials began emerging around the eight-week mark, with fertility studies typically running for 12 weeks. A year-long safety study of a standardized extract found no concerning trends in lab values over that period.17PubMed Central. Safety of 12-Months Administration of Ashwagandha (Withania somnifera) Standardized Root Extract in Healthy Adults: A Prospective, Observational Study
The word “standardized” matters. Different ashwagandha products contain wildly different concentrations of withanolides, the active compounds responsible for most of the herb’s biological effects.22PubMed Central. Pharmacological Insights Into Ashwagandha (Withania somnifera): A Review of Its Immunomodulatory and Neuroprotective Properties A product labeled “ashwagandha 600 mg” that uses raw root powder delivers far less active content than a concentrated extract standardized to a specific withanolide percentage. If you are trying to replicate what the clinical trials tested, look for products that specify withanolide content and match the extract type used in published research.
Contamination in Supplements
Because ashwagandha is sold as a dietary supplement rather than a drug, it is not subject to pre-market approval in most countries. That creates a contamination problem. A laboratory analysis of adaptogenic herbal supplements, including ashwagandha products, found that the majority of tested samples exceeded permissible limits for lead and nickel as defined by European Pharmacopoeia and WHO guidelines. Cadmium and mercury levels were within acceptable limits, but lead and nickel exceedances were widespread and in many cases far above threshold values.23PubMed Central. Heavy Metal Contamination in Adaptogenic Herbal Dietary Supplements: Experimental, Assessment and Regulatory Safety Perspectives
Heavy metal contamination is not unique to ashwagandha; it is a known problem across the herbal supplement industry. But it adds a genuine health risk on top of whatever the herb itself does. Choosing products that carry third-party testing certifications from organizations like NSF International, USP, or ConsumerLab can reduce this risk, though it cannot eliminate it entirely. Men who plan to take ashwagandha long-term should factor supplement quality into their decision at least as seriously as they consider dosage.
Metabolic Effects Still Under Investigation
An emerging area of interest is ashwagandha’s potential role in insulin sensitivity and metabolic health. Lab and animal research has shown that the herb can inhibit certain enzymes involved in carbohydrate digestion, increase insulin secretion from the pancreas, and improve how organs respond to insulin.24PubMed Central. Ashwagandha (Withania somnifera) in insulin resistance and metabolic syndrome: A literature review on mechanisms These findings are largely preclinical, meaning they have been observed in cell cultures and animal models rather than in large human trials. The mechanisms are biologically plausible and could eventually prove relevant for men dealing with early-stage metabolic dysfunction, but it would be premature to take ashwagandha specifically for blood sugar management based on current evidence. If this area interests you, it is worth watching for human trials in the next few years.