Tongkat Ali (Eurycoma longifolia)
Tongkat ali is a root extract of Eurycoma longifolia standardised to eurycomanone and glycosaponins, used as an aphrodisiac and testosterone-support supplement. Several small human trials suggest it can modestly raise testosterone in men with low baseline levels and improve stress hormones and libido, but the evidence base is small and much of it is industry-linked. Marketed under branded extracts such as LJ100 and Physta.
01 Overview
Quassinoids such as eurycomanone are proposed to increase testosterone by reducing sex-hormone-binding globulin binding and supporting steroidogenesis, and the herb also appears to lower cortisol and improve stress-related mood in some trials. Reported benefits are most pronounced in hypogonadal, older or stressed men, with little clear effect in already-eugonadal young athletes.
Users take standardised extracts daily for libido, wellbeing and a mild hormonal lift rather than as a pharmaceutical androgen. It is broadly well tolerated. A recurring quality concern is mercury and lead contamination of some raw-root products, so standardised, tested extracts are preferred.
02 Mechanism
Quassinoid-rich root extract (chiefly eurycomanone) proposed to free bound testosterone from SHBG, support Leydig-cell steroidogenesis and lower cortisol, improving the testosterone-to-cortisol ratio.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Standardised extract | 200–400 mg/day | Oral | Typical dosing of water-standardised extracts (e.g. ~2% eurycomanone). |
| Higher trial dosing | 400–600 mg/day | Oral | Upper range used in some fatigue/hormone studies. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Improved libido and erectile satisfactionRepeatedly reported in questionnaire-based trials, particularly in men with reduced baseline sexual function. | subjective | Observational | |
| Modest testosterone increase in low-T menSome placebo-controlled trials show raised testosterone in hypogonadal or stressed subjects; little effect in eugonadal young men. | small | Clinical | |
| Lower cortisol / improved stress ratioReported reductions in cortisol and improved testosterone:cortisol ratio in stressed adults. | modest | Observational |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Insomnia / restlessnessStimulating effect can disrupt sleep, especially with later-day dosing. | Mild | Common | Anecdotal | |
| Heavy-metal contaminationSome raw-root Eurycoma products have tested positive for mercury and lead above safety limits. | Moderate | Product-dependent | Observational | |
| Irritability / agitationSome users report irritability or feeling 'wired' at higher doses. | Mild | Uncommon | Anecdotal |