Tongkat ali (Eurycoma longifolia) is one of the most well-researched natural herbal extracts for testosterone and hormonal health. The plant originates from the rainforests of Malaysia and Indonesia and has been used in Southeast Asian folk medicine for hundreds of years. Over the past two decades it has climbed onto biohacking radars worldwide – and for good reason. There are real studies on real humans, not just rats.
This guide covers what the research actually says, how tongkat ali works mechanistically, who benefits most, how to dose it and how to choose a serious supplement. We take the sober analysis, not the hype version.
What is tongkat ali?
Tongkat ali is also known as longjack or eurycoma longifolia. The root contains over 65 identified bioactive compounds – the most important being eurycomanones (quassinoids), eurypeptides and glycosaponins. The chemical complexity is part of why the research can be difficult to interpret: it is not a single-molecule drug with one clear mechanism, but a mixture of compounds acting via multiple parallel pathways.
The Malaysian government invested public research funding in tongkat ali as far back as the 1990s via the Forest Research Institute of Malaysia – unusual for an herb and a sign there is real substance behind the interest.
What does the research say about testosterone?
The central question is whether tongkat ali actually raises testosterone – and the answer is yes, but with an important qualification.
A systematic review and meta-analysis published in 2022 in Medicina pooled data from five randomised controlled trials involving 232 men. Results showed a statistically significant increase in total testosterone (SMD = 1.352, 95% CI 0.565–2.138, p = 0.001). That is a meaningful effect size – but who benefits most is the critical question.
The strongest effects were seen in men with low baseline testosterone (below 300 ng/dL). In hypogonadal men the improvement was both statistically and clinically significant. In healthy men with normal testosterone levels the trend was positive but not statistically robust.
Sober conclusion: Tongkat ali appears to restore testosterone that has dropped below normal – not pump levels above your natural ceiling. Researchers describe it as a "restorer" rather than a "booster".
An early key study in Andrologia followed 76 older men with diagnosed hypogonadism taking 200 mg standardised extract daily for one month. Before treatment only 35.5% had testosterone within the normal range. Afterwards: 90.8% – and symptom scores on the AMS scale improved dramatically.
How does it work mechanistically?
- SHBG release: Eurypeptides are thought to release testosterone from SHBG (sex hormone-binding globulin) – a transport protein that keeps testosterone inactive. Less SHBG binding means more free, biologically active testosterone without the body needing to produce more.
- LH stimulation: Eurycomanone stimulates release of luteinising hormone (LH) from the pituitary, driving testosterone synthesis in the Leydig cells of the testes.
Study overview
| Study | Population | Dose | Duration | Result |
|---|---|---|---|---|
| Leisegang et al. 2022 (meta-analysis) | 232 men, 5 RCTs | 100–600 mg/day | Varied | SMD = 1.352, p = 0.001 |
| Tambi et al. 2012 | 76 hypogonadal men | 200 mg/day | 4 weeks | Normal T: 35.5% → 90.8% |
| Henkel et al. 2014 | 25 seniors 57–72 yrs | 400 mg/day | 5 weeks | Significant increase, both sexes |
| Leitão et al. 2021 | 45 men with ADAM | 200 mg/day | 6 months | Significant increase with exercise |
Cortisol and stress – the other half of the picture
Chronic stress drives cortisol up and testosterone down – a hormonal pattern contributing to fatigue, irritability, poor recovery and increased fat storage. Tongkat ali appears able to break that cycle.
The most cited stress study, published in the Journal of the International Society of Sports Nutrition, included 63 moderately stressed adults. Half took 200 mg standardised extract daily, half placebo. After four weeks the supplement group showed a 16% reduction in salivary cortisol, a 37% increase in salivary testosterone and a 36% improvement in the cortisol-to-testosterone ratio.
Athletic performance, muscle and fertility
Tongkat ali is popular among fitness enthusiasts – but does the performance evidence hold up? Data is promising but limited. A study on older active men (57–72 years) showed increased muscle strength over five weeks with 400 mg/day.
What tongkat ali is not: anabolic steroids. It does not stimulate androgen receptors directly and does not produce the dramatic muscle gains steroids give. It is best suited as support for the hormonal environment – not as a primary muscle builder.
Sperm quality and male fertility
An often-overlooked area is fertility effects. Studies have shown improvements in sperm count, sperm motility and sperm quality in infertile men treated with tongkat ali extract. For couples working on fertility optimisation, tongkat ali may be a relevant adjunct to discuss with a doctor.
Who benefits most?
- Most benefit: Men over 35–40 with signs of declining testosterone – lower energy, reduced libido, worse training results, poor recovery
- Good benefit: Active men and women with high stress levels where the cortisol-testosterone balance is affected
- Fertility focus: Men with reduced sperm quality – research supports positive effects
- Limited benefit: Young healthy men with testosterone at the high end of the normal range
Yellow, red and black tongkat ali – what is the difference?
The market sells "red", "yellow" and "black" tongkat ali as if they were variants of the same plant. This is misleading. Yellow tongkat ali (Eurycoma longifolia) is the scientifically studied variant with all clinical evidence behind it. Red (Stema tuberosa) and black are entirely different plants with little or no clinical research. We have a detailed guide on the differences.
Dosage
- Extract quality is everything – look for products standardised to at least 1–2% eurycomanones. LJ100 and Physta are the two well-studied extract forms.
- Take in the morning with food – tongkat ali has a mildly energising effect and may disrupt sleep if taken late.
- Effects become noticeable after 2–4 weeks of consistent use.
- Cycling: 5 days on / 2 days off, or continuously for up to 12 weeks, are common protocols.
Safety and side effects
Tongkat ali is well-tolerated by most at recommended doses and does not bind to androgen receptors like anabolic steroids. Possible side effects: mild sleep disturbance (do not take in the evening), slight stomach discomfort (minimised with food), increased heart rate in sensitive individuals at high doses.
EFSA issued a 2021 warning that tongkat ali showed potential to cause DNA damage at high doses in animal studies. Human data at normal doses does not show this, but stay within recommended amounts.
Stacking with other supplements
- Tongkat ali + Ashwagandha: Complementary mechanisms – tongkat ali raises LH and supports testosterone; ashwagandha lowers cortisol that would otherwise suppress production.
- Tongkat ali + Fadogia Agrestis: Popular biohacking stack – tongkat ali via SHBG release, fadogia via LH stimulation.
- Tongkat ali + Zinc: Zinc deficiency lowers testosterone; the combination addresses deficiency and optimisation simultaneously.
Find Noop's tongkat ali in our hormones and libido collection.
FAQ
Is tongkat ali legal?
Yes. Tongkat ali is a legal dietary supplement in the EU and is not banned by WADA.
How long does it take for tongkat ali to work?
Most studies show measurable effects after 2–4 weeks of daily use. Hormonal changes take time.
Can tongkat ali replace testosterone replacement therapy (TRT)?
No. Tongkat ali supports the body's own production – it does not supply testosterone from outside. For clinically diagnosed hypogonadism, TRT is the medical standard.
Can women take tongkat ali?
Yes. Some research shows effects on stress and energy. Pregnant and breastfeeding women should avoid it.
Which tongkat ali extract is best?
Physta (standardised to 0.8% eurycomanones and 22% polysaccharides) and LJ100 (standardised to 40% glycosaponins) have the most clinical evidence. Choose products with stated standardisation and third-party analysis (COA).