Tongkat Ali (Eurycoma longifolia), sometimes called "longjack," is a root long used in Malaysian and Indonesian traditional medicine — and today it's one of the more clinically studied botanicals in men's health. Here's a plain-language look at the actual research.
A Traditional Root With Real Modern Research
Tongkat Ali grows in the rainforests of Southeast Asia, where it has been used for generations as a folk remedy for fatigue, low libido, and general vitality. Unlike many traditional botanicals, Tongkat Ali has been the subject of a genuinely meaningful body of human clinical research over the past two decades.
Testosterone: The Strongest Evidence
This is where Tongkat Ali's research is most developed. Across nine randomized controlled trials, supplementation with Tongkat Ali extract was associated with a significant increase in total testosterone in both healthy adults and men with clinically low testosterone (hypogonadism). In some of these studies, a 200 mg daily dose brought testosterone levels into the normal range for more than 90% of participants who started with low levels.
Libido and Sexual Wellness
In a 12-week study, men who took 300 mg of Tongkat Ali extract twice daily reported an increase in subjective libido scores of just over 14% — a change researchers linked to rising testosterone levels. Tongkat Ali is also thought to support healthy blood flow by helping preserve cGMP, a signaling molecule involved in smooth muscle relaxation.
Fast Facts
- Nine randomized controlled trials link Tongkat Ali supplementation to increased testosterone.
- A 12-week study found a ~14% increase in subjective libido scores at 300 mg twice daily.
- A 2013 study found a 16% reduction in salivary cortisol at 200 mg/day in moderately stressed adults.
- Most other traditional claims about Tongkat Ali are less rigorously studied than these three areas.
Stress and Cortisol
A 2013 study of 63 adults with moderate stress found that 200 mg of Tongkat Ali extract per day reduced salivary cortisol levels by 16% compared to placebo, alongside self-reported reductions in stress, anger, and tension. Since chronic elevated cortisol can work against healthy testosterone levels, this stress-reducing effect may partly explain Tongkat Ali's hormonal benefits.
Keeping It in Perspective
Tongkat Ali is genuinely one of the better-researched botanicals in this category, but it's not a miracle herb — most other claims associated with it (like effects on fertility, muscle mass, or mood beyond stress reduction) are based on smaller or more preliminary studies. It's best thought of as a promising, moderately well-supported ingredient rather than a guaranteed fix.
Safety Considerations
Tongkat Ali is generally well tolerated at studied doses (typically 200–400 mg/day of standardized extract). As with any ingredient that affects hormone levels, check with a healthcare provider before use, particularly if you have a hormone-sensitive condition.
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