Research dossier
Clinical research on Tongkat Ali
7 trials reviewed across 4 indications.
Strongest evidence
Testosterone & androgen support
Mechanism
Quassinoids in the root extract — chiefly eurycomanone — are proposed to reduce conversion of testosterone to estrogen and to lower SHBG, freeing more bioavailable testosterone. The mechanism is plausible but not definitively mapped in humans.
The 2022 meta-analysis (5 RCTs, n=267) found a significant testosterone rise, largest in men starting below 300 ng/dL. But heterogeneity was extreme (I²=87%), small-study bias was flagged, and most trials used the same manufacturer's extract. Real signal in low-T older men; weak and inconsistent in healthy young men.
Most credible in older or hypogonadal men (baseline T <300 ng/dL). Evidence in young, eugonadal men is thin and easily overstated by marketing.
Trials cited
Eurycoma longifolia and total testosterone (meta-analysis of 5 RCTs)
positive · Meta-analysis
Leisegang et al., 2022, Medicina (Kaunas)n=267Nine studies were screened and five RCTs (n=267) pooled. Tongkat ali raised total testosterone with a large standardized effect (SMD 1.35, 95% CI 0.57–2.14, p=0.001). The effect was largest in men with baseline testosterone below 300 ng/dL.
Heterogeneity was very high (I²=87%) and Begg's test flagged small-study/publication bias (p=0.02). Most included trials used the same commercial extract and several were manufacturer-linked. A real signal, but fragile and likely inflated.
Physta® in ageing men with low testosterone
positive · RCT
Chinnappan, George et al., 2021, Food & Nutrition Researchn=105Industry-fundedDouble-blind multicentre RCT in 105 low-testosterone older men. The 200 mg Physta® group raised total testosterone significantly vs placebo from week 4 onward, with reductions in aging-symptom and fatigue scores in both active groups.
Manufacturer-linked (Physta® is made by Biotropics Malaysia; authors include company-affiliated staff). Selected for low baseline testosterone — the population where benefit is most expected.
Tongkat ali in physically active seniors (pilot)
positive · Pilot
Henkel et al., 2014, Phytotherapy Researchn=25Small open pilot: 5 weeks of 400 mg/day raised total and free testosterone and grip strength in both men and women. In women the free-testosterone rise tracked a drop in sex-hormone-binding globulin.
Pilot study, n=25, no placebo control reported for the strength outcomes. Encouraging but hypothesis-generating, not confirmatory.
Tongkat ali in late-onset hypogonadism (single-arm)
positive · Observational
Tambi et al., 2012, Andrologian=7676 men with late-onset hypogonadism took 200 mg/day for one month; the share with normal testosterone rose from ~35% to ~91%, and symptom scores improved.
Open-label, single-arm, no placebo group — the dramatic numbers are uncontrolled and cannot separate the extract from regression to the mean or measurement timing. Frequently cited as if it were an RCT; it is not.
Stress & cortisol
Mechanism
Proposed modulation of the cortisol-to-testosterone ratio under stress, shifting the body away from a catabolic state. Mechanistically reasonable, clinically underpowered.
Rests on essentially one 4-week RCT (n=63) showing a ~16% drop in salivary cortisol and mood improvements. Encouraging but single, short, small, and using salivary hormones that fluctuate heavily. Not an established stress treatment.
Tested only in moderately stressed adults over 4 weeks. No long-term or clinical-anxiety data.
Tongkat ali for stress hormones and mood
positive · RCT
Talbott et al., 2013, Journal of the International Society of Sports Nutritionn=63Industry-fundedIn 63 moderately stressed adults, 4 weeks of 200 mg/day lowered salivary cortisol (~16%), raised salivary testosterone (~37%), and improved tension, anger, and confusion scores vs placebo.
Short (4 weeks), small, and uses salivary rather than serum hormones. Manufacturer-supplied extract; the headline +37% testosterone is a salivary measure prone to large swings.
Male sexual function & fertility
Mechanism
Downstream of any testosterone or SHBG effect, plus possible direct effects on sperm motility seen in subgroup analyses.
Two RCTs report improved erectile-function scores, with semen-parameter gains limited to men with low baseline values. The standalone supplement effect is modest; the clearer ADAM result came from combining it with exercise. Industry funding and subgroup-restricted fertility findings warrant caution.
Erectile and fertility signals are strongest in men with low baseline testosterone or poor baseline semen quality — not a general male-fertility booster.
Physta® for quality of life and sexual well-being
mixed · RCT
Ismail, George et al., 2012, Evidence-Based Complementary and Alternative Medicinen=109Industry-fundedIn 109 healthy middle-aged men, 12 weeks of 300 mg/day improved SF-36 physical functioning and IIEF erectile-function scores vs placebo, with libido and semen-parameter gains in a subgroup with low baseline values.
Funded by Biotropics Malaysia Berhad (the manufacturer); two authors were company employees. Semen and libido gains were limited to subjects with low baseline values, inviting selective reporting.
Tongkat ali ± concurrent training in ADAM
mixed · RCT
Leitão et al., 2021, Maturitasn=45Four-arm RCT crossing supplement with exercise. Erectile function improved across active arms, but the largest, clearest gains came from the combination of exercise plus tongkat ali — the supplement alone was the weaker mover.
Only 45 men split across four arms (~11 each) — underpowered to isolate the supplement's standalone effect. The standout result is for exercise plus supplement, not supplement alone.
Muscle strength & body composition
Mechanism
Hypothesized via raised free testosterone supporting lean mass and force production.
A single 5-week pilot (n=25) reported grip-strength gains in seniors. There is no adequately powered, placebo-controlled trial of tongkat ali for muscle or athletic performance. Ergogenic claims outrun the data.
One small uncontrolled pilot. Treat strength/performance claims as unproven.
Tongkat ali in physically active seniors (pilot)
positive · Pilot
Henkel et al., 2014, Phytotherapy Researchn=25Small open pilot: 5 weeks of 400 mg/day raised total and free testosterone and grip strength in both men and women. In women the free-testosterone rise tracked a drop in sex-hormone-binding globulin.
Pilot study, n=25, no placebo control reported for the strength outcomes. Encouraging but hypothesis-generating, not confirmatory.
4 forms of Tongkat Ali compared
Standardized water (hot-water) root extract
The form used in essentially every positive RCT
Best forTestosterone, stress, sexual functionAll the credible human data use standardized aqueous root extracts — not raw root powder. Standardization is usually quoted as a eurycomanone percentage or an extract ratio (often quoted as ~50:1 or 100:1, though ratio alone says nothing about active content).
Physta®
Physta® standardized extract
Standardized to 0.8–1.5% eurycomanone plus defined glycoprotein/polysaccharide fractions
Best forThe extract behind most of the published trialsMade by Biotropics Malaysia. Seven of nine studies in the 2022 meta-analysis used it. This is both a strength (consistent material) and a weakness (most evidence is manufacturer-linked and not independently replicated).
LJ100®
LJ100® standardized extract
Standardized to 40% glycosaponins, 22% eurypeptides, ~0.8–1.5% eurycomanone
Best forTestosterone and sexual-function formulasA licensed extract (originating from MIT/government research) used in several trials. Like Physta®, it is a defined, standardized material — preferable to unstandardized root powder.
Raw root powder (unstandardized)
Unknown and inconsistent — no defined eurycomanone content
Best forCheap bulk powder; not the form studiedRaw, unstandardized powder is not what the trials used. Active quassinoid content is unverified, and unstandardized Malaysian/Indonesian root products are the category most associated with heavy-metal contamination.
Side effects and drug interactions
Side effects
Insomnia and restlessness
Common
The stimulating, slightly androgenic profile can disrupt sleep, especially when dosed late in the day.
Irritability or agitation
Uncommon
Some users report increased irritability or 'edgy' energy, plausibly linked to the testosterone/cortisol shift.
GI upset
Uncommon
Mild nausea or stomach discomfort, generally dose-related.
Heavy-metal exposure from contaminated product
Severe
Not an effect of the herb itself but of poor sourcing. Independent surveys of Malaysian tongkat ali products found mercury (and in some cases lead, cadmium, arsenic) above local limits in a substantial fraction of products. This is a real, documented risk — not a theoretical one.
Worse with:tongkat ali root powder
Gentler:physta, lj100, tongkat ali water extract
Drug interactions
Additive effect
antihypertensivesantidiabetic drugs (insulin, sulfonylureas)Animal and small human data suggest possible blood-pressure and glucose-lowering effects that could be additive with medication.
Monitor blood pressure and blood glucose if combining; the human evidence is limited, so caution is precautionary.
Other
testosterone replacement therapyanti-androgenshormone-sensitive conditionsAny genuine androgenic effect could compound TRT or oppose anti-androgen therapy, and is theoretically unwanted in hormone-sensitive cancers (e.g. prostate).
Discuss with a clinician before combining with hormone therapy or if you have a hormone-sensitive condition.
Additive effect
anticoagulantsantiplatelet drugsSome in-vitro and animal data suggest antiplatelet activity; clinical relevance is unclear.
Use caution before surgery or alongside blood thinners.
Other critical caveats
- Most of the positive human evidence comes from one standardized extract (Physta®) and trials linked to its manufacturer. Independent replication is limited — read the testosterone claims as promising but not established.
- Heavy-metal contamination is a documented, real-world problem: independent surveys of Malaysian tongkat ali products found mercury above local limits in roughly a quarter to a third of products tested, plus lead, cadmium, and arsenic in some. Buy only standardized extracts with a third-party certificate of analysis.
- The famous single-arm Tambi study (testosterone normalizing in ~91% of hypogonadal men) had no placebo group and is uncontrolled — it is routinely miscited as proof of efficacy.
- Benefit is concentrated in older or hypogonadal men (baseline testosterone <300 ng/dL). Evidence that it does anything meaningful for healthy young men is weak.
Frequently asked
Does tongkat ali actually raise testosterone?
Modestly, and mostly in the men who need it. A 2022 meta-analysis of 5 RCTs found a significant testosterone increase, biggest in men starting below 300 ng/dL. But the trials were small, statistically heterogeneous, showed signs of small-study bias, and mostly used one manufacturer's extract. In healthy young men the effect is weak and easy to overstate.What dose and form should I use?
Trials used 200–400 mg/day (some up to 600 mg) of a standardized water extract — Physta® or LJ100® standardized to roughly 0.8–1.5% eurycomanone. Avoid raw, unstandardized root powder: the active content is unverified and it's the form most linked to heavy-metal contamination.Is tongkat ali safe? What about mercury?
The extract itself is generally well tolerated short-term (some insomnia, irritability, mild GI upset). The bigger issue is sourcing: independent surveys found mercury above limits in a meaningful share of Malaysian tongkat ali products, plus other heavy metals. Only buy products with a third-party heavy-metal certificate of analysis.Does it help with stress?
One 4-week RCT (n=63) found a ~16% drop in salivary cortisol and better mood scores. That's one short, small, manufacturer-supplied study using salivary hormones — encouraging but far from established. Don't treat it as a proven stress remedy.Will it boost strength or athletic performance?
There's no good evidence for that. The only strength data come from a single 5-week pilot in 25 seniors with no proper placebo control. Ergogenic and bodybuilding claims run well ahead of the science.
References
- 01Leisegang et al., 2022 — Eurycoma longifolia and total testosterone, meta-analysis (Medicina)
- 02Chinnappan & George et al., 2021 — Physta® in ageing men, RCT (Food & Nutrition Research)
- 03Talbott et al., 2013 — Tongkat ali, stress hormones and mood, RCT (J Int Soc Sports Nutr)
- 04Ang & Lee, 2006 — Contamination of mercury in tongkat ali herbal preparations (Food Chem Toxicol)
- 05Examine.com — Eurycoma longifolia (Tongkat Ali)
Last reviewed2026-05-24