Several herbs have shown measurable increases in testosterone in clinical trials, with ashwagandha and fenugreek carrying the strongest evidence. Most studies report increases in the range of 10–20% over baseline, typically after 8 to 12 weeks of daily supplementation. That said, the size of the effect varies based on age, baseline hormone levels, and the specific extract used.
Ashwagandha
Ashwagandha is the most consistently studied herb for testosterone support. Across multiple trials, standardized extracts have produced testosterone increases between 15% and 17% compared to placebo groups. In one trial, 600 mg daily of a concentrated root extract for 8 weeks raised testosterone by 15.3%. Another using 675 mg daily for 90 days saw a 17.3% increase. A third study in overweight men aged 40–70 found a 14.7% increase after 8 weeks.
The mechanism is partly indirect. Ashwagandha lowers cortisol by acting on your body’s stress-response system. Cortisol and testosterone have an inverse relationship: when stress hormones stay chronically elevated, testosterone production drops. By bringing cortisol down, ashwagandha removes one of the brakes on testosterone output. This is why the effects tend to be more pronounced in people who are stressed, sleep-deprived, or overweight, since those groups typically have higher baseline cortisol.
Most trials use one of two branded extracts (KSM-66 or Shoden), standardized to specific concentrations of the plant’s active compounds. Generic ashwagandha powder hasn’t been tested the same way, so the results may not translate directly.
Fenugreek
Fenugreek seed extracts have shown reliable testosterone increases across several trials, with effects ranging from about 7% to 23% depending on the extract and population studied. In one 12-week trial of 120 overweight men, 600 mg daily of a standardized fenugreek extract raised total testosterone by 12.2%, while the placebo group actually dropped by 6.1%. A smaller study in young men (ages 18–24) found a 6.6% increase in total testosterone and a 12.3% increase in bioavailable testosterone after just 8 weeks on 500 mg daily.
Fenugreek contains specialized plant compounds called glycosides that appear to have both androgenic and anabolic effects. One interesting finding: a single-dose study showed a measurable testosterone increase within 10 hours, making fenugreek one of the few herbs with evidence of acute effects. Still, consistent daily use for at least 8 weeks produces the most meaningful changes. Dosages in successful trials ranged from 250 to 600 mg daily, always using extracts standardized for specific active compounds rather than raw fenugreek powder or the spice you’d use in cooking.
Tongkat Ali
Tongkat ali (also called longjack or Malaysian ginseng) has a growing body of evidence behind it. A 2022 meta-analysis pooling nine clinical trials found a statistically significant increase in total testosterone across studies, with the strongest effects seen in men who had low testosterone at baseline. Dosages ranged from 100 to 600 mg daily, with treatment periods lasting up to six months.
The evidence for free testosterone, the form your body actually uses, is less consistent. Three of six studies measuring free testosterone found significant increases, while the others did not. This suggests tongkat ali’s effects on usable testosterone may depend on individual factors like age and starting hormone levels. Most commercial products use a water-extracted form of the root, which is what the majority of trials tested.
Other Herbs With Limited Evidence
Forskolin
An extract from the plant Coleus forskohlii showed a 13.6% testosterone increase after 12 weeks at 500 mg daily in one study. The evidence is thin, limited to a single trial, but the result was statistically significant compared to placebo.
Asian Red Ginseng
Korean red ginseng at 3 grams daily for 4 weeks produced a modest 5.6% increase in total testosterone in one controlled trial. That’s a smaller effect than ashwagandha or fenugreek, and the study was short, so it’s hard to know whether longer use would produce a larger change.
Shilajit
Shilajit, a mineral-rich resin found in Himalayan rock, significantly increased total testosterone, free testosterone, and a testosterone precursor hormone called DHEAS after 90 days in one placebo-controlled study. The research is limited to small trials, but the results were consistent across multiple hormone markers.
Tribulus Terrestris Doesn’t Work
Tribulus is one of the most heavily marketed “testosterone boosters,” but the evidence doesn’t support the claim. A systematic review of ten clinical trials found that eight showed no significant change in testosterone. The only two studies reporting increases involved men who already had clinically low testosterone, and even then the increases were small (60–70 ng/dL) with poor study quality. If your testosterone is in a normal range, tribulus is unlikely to move it. It may have some benefit for erectile function through a completely separate mechanism involving nitric oxide and blood flow, but that’s not a testosterone effect.
How Long Before You See Results
Most successful trials ran for 8 to 12 weeks before measuring testosterone changes. That’s the realistic minimum timeframe. A few studies detected shifts earlier, including the fenugreek trial that found an acute response within 10 hours, but meaningful, sustained increases in testosterone take consistent daily use over two to three months.
If you want to verify the effect, get a baseline testosterone blood draw before starting supplementation and a follow-up test after 10–12 weeks. Test in the morning, since testosterone peaks early in the day and declines throughout the afternoon. Without blood work, you’re guessing.
Safety and Interactions
Herbal supplements have real biological activity, which means they can also cause real side effects or interact with medications. Liver toxicity is a documented risk with many herbal products, and the list of implicated supplements continues to grow. Fewer than 40% of people who take herbal products mention it to their doctor, which creates a blind spot for catching drug interactions.
Ashwagandha can cause gastrointestinal discomfort in some people, and because it modifies stress hormone pathways, it may interact with thyroid medications or immunosuppressants. Fenugreek can lower blood sugar, which matters if you take diabetes medication. Tongkat ali at high doses has been associated with restlessness and insomnia in some users.
The supplement industry is also poorly regulated. Products may contain less of the active compound than labeled, or include contaminants. Choosing products that use the same branded, standardized extracts tested in clinical trials (and that carry third-party testing certifications) reduces this risk considerably. The gap between a clinically tested extract and a cheap generic powder from an unknown manufacturer is not trivial.