Ashwagandha is a small evergreen shrub whose root has been used in Indian Ayurvedic medicine for centuries. Modern supplements are usually root or root-and-leaf extracts standardised to compounds called withanolides, which are thought to be the main active ingredients. It is often described as an adaptogen, a term for herbs said to help the body cope with stress.
For men, the interest is mainly in testosterone, libido and fertility. A 2026 meta-analysis of 23 placebo-controlled trials (1,706 participants) found that ashwagandha lowered the stress hormone cortisol and raised testosterone in men by an average of about 57 ng/dL, with no effect in women1. The trials used a range of extracts and amounts, and the authors called for more standardised studies.
If you have symptoms of low testosterone, such as low sex drive, fewer morning erections or persistent tiredness, get a proper blood test so a doctor can check for hypogonadism and its causes.
Does ashwagandha raise testosterone?
Pooled trials show an average rise in testosterone in men compared with placebo, alongside lower cortisol. The size of the effect has varied between trials.
In the largest pooled analysis so far, ashwagandha increased testosterone in men compared with placebo and also reduced cortisol1. The authors noted variation between trials, which used different extracts and amounts, and called for more standardised studies.
One well-designed crossover trial in overweight men aged 40 to 70 with mild fatigue gives a closer look. Men taking an extract (the trial used one delivering 21 mg of withanolide glycosides a day) for eight weeks had a 14.7% greater rise in salivary testosterone and an 18% greater rise in DHEA-S, another hormone linked to vitality, than on placebo. Fatigue, vigour and sexual wellbeing improved during both the ashwagandha and placebo phases2. For context on how testosterone normally shifts with age, see how testosterone changes after 40.
What have studies found on ashwagandha and fertility?
Studies in men with low sperm counts found higher sperm concentration, semen volume and motility after 90 days. Most compared men with their own starting results, and the reviewers called for larger randomised trials.
A 2018 systematic review found four clinical trials of ashwagandha in infertile men, one of them randomised. After 90 days, men with low sperm counts had increases of 167% in sperm concentration, 59% in semen volume and 57% in motility compared with their starting levels, along with higher testosterone and LH. No side effects were reported3.
Sperm take weeks to develop (see how long sperm take to regenerate), so fertility studies need to run for several months. If you are trying to conceive, a semen analysis and a GP appointment help show where to focus.
Is ashwagandha safe?
Most trial participants tolerate it, but it is not risk-free. Rare cases of liver injury have been reported, and it may nudge thyroid hormone levels.
A case series from Iceland and the US Drug-Induced Liver Injury Network described five people who developed jaundice, itching, nausea and lethargy after two to 12 weeks of taking ashwagandha supplements. None developed liver failure, and liver tests returned to normal within one to five months in the four patients who were followed up4. Stop taking it and see a doctor promptly if you notice yellowing of your skin or eyes, dark urine or persistent itching.
Pooled trials also found a small rise in the thyroid hormone T41. Talk to a doctor before using ashwagandha if you have a thyroid condition or take thyroid medication, have liver disease, or take any regular prescription medicine.
Common questions
How long does ashwagandha take to work?
Trials in men have typically run for eight weeks2 to 90 days3. Any effect on sperm is likely to take several weeks to show, because sperm take that long to develop.
Does ashwagandha increase libido?
Ashwagandha research in men has focused mainly on hormones, stress and fertility. In a placebo-controlled trial of middle-aged men, testosterone rose with ashwagandha, and sexual wellbeing improved over the course of the study in both phases2. Stress, sleep and relationships matter too; see our guide to how stress affects erections and libido.
Read more on this
Supplement ingredients for men’s sexual health: what the research shows
How stress affects erections and libido
How testosterone changes after 40 (and what actually helps)
Sources
- Fornalik M, et al. Hormonal Modulation with Withania somnifera: Systematic Review and Meta-Analysis of Randomized-controlled Trials. Planta Med. 2026;92:790-805. PubMed
- Lopresti AL, et al. A Randomized, Double-Blind, Placebo-Controlled, Crossover Study Examining the Hormonal and Vitality Effects of Ashwagandha (Withania somnifera) in Aging, Overweight Males. Am J Mens Health. 2019;13(2):1557988319835985. PubMed
- Durg S, et al. Withania somnifera (Indian ginseng) in male infertility: An evidence-based systematic review and meta-analysis. Phytomedicine. 2018;50:247-256. PubMed
- Björnsson HK, et al. Ashwagandha-induced liver injury: A case series from Iceland and the US Drug-Induced Liver Injury Network. Liver Int. 2020;40(4):825-829. PubMed
Not medical advice. Written by Eric Stephens from the research cited above; not reviewed by a doctor. If something worries you, see a GP.