Verdict: Modest testosterone rise in men with low levels, weak in healthy men, real quality concerns, no VO2max benefit
Safety: EFSA says safety not established (DNA damage signal); mercury, lead and sildenafil found in some products
Key takeaways
A 2022 meta-analysis of five small trials found tongkat ali raised total testosterone, with the effect driven by men with low testosterone and not significant in healthy men
The trials were few, very heterogeneous and showed signs of publication bias, and most used a single branded extract
Tongkat ali products have been found contaminated with mercury and lead or spiked with sildenafil, and EFSA concluded its safety is not established
Tongkat ali (Eurycoma longifolia), also called Malaysian ginseng or longjack, is a Southeast Asian root that has become one of the most searched "testosterone boosters". Unlike many booster ingredients, it does have a meta-analysis behind it. The catch is that the effect is mostly seen in men with low testosterone, the trials are small, and the products themselves have a troubled quality record.
What it is
Tongkat ali is a shrub whose root has been used in traditional medicine in Malaysia and Indonesia for male sexual function, fertility and "energy". Supplements are usually hot-water root extracts, sometimes standardised to eurycomanone, a compound thought to be active. Most trials in the main meta-analysis used one branded, standardised extract.
Does it raise VO2max?
No. No trial has measured a meaningful rise in VO2max with tongkat ali, and there is no plausible route for it to enlarge the heart or increase blood volume, the main limits on VO2max (see what limits VO2max). Testosterone does affect haemoglobin, but a booster-sized nudge within the normal range is not the same as medical testosterone therapy (see testosterone, endurance training and VO2max).
Does it improve endurance performance?
There is no good evidence that it does. The research is about testosterone, mood and strength.
Leisegang et al., 2022 — systematic review and meta-analysis
This review (Medicina, 2022) included nine studies and pooled five randomised trials. Tongkat ali raised total testosterone overall, but the details matter:
- The effect was driven by men with hypogonadism (low testosterone). In healthy men the increase was not statistically significant.
- Heterogeneity was very high (I² about 87%), and the authors detected publication bias.
- Doses ranged from 100 to 600 mg a day, for anything from 3 days to 6 months, mostly of one branded extract.
- The authors called it "promising" but said more research is needed before clinical use.
Other trials
- Talbott et al., 2013 (JISSN): in 63 moderately stressed adults, 4 weeks of root extract improved some mood scores and lowered salivary cortisol while raising salivary testosterone compared with placebo. Salivary hormones are a rough measure.
- Henkel et al., 2014 (Phytother Res): 25 physically active adults aged 57–72 took 400 mg a day for 5 weeks. Total and free testosterone and handgrip strength increased, but there was no placebo group.
How it is used in studies
Trials used 100–600 mg a day, mostly of a standardised hot-water root extract. Products vary enormously: an analysis cited in the 2022 review tested 41 products: only 24 contained any eurycomanone at all, and just 11 of those met the recommended level. Results from one extract do not transfer to another.
Side effects, safety and anti-doping
Short trials report few side effects. The longer-term picture is less reassuring:
- EFSA (2021) assessed a tongkat ali root extract as a novel food and found it could cause DNA damage in lab and animal tests. It concluded that safety has not been established under any condition of use.
- Heavy metals: in a study of 100 tongkat ali products sold in Malaysia, 26% contained mercury above the national limit (Ang and Lee, 2006). Lead contamination has also been reported.
- Hidden drugs: products marketed with tongkat ali have been found spiked with sildenafil, the erectile dysfunction drug. Sexual enhancement is the most common category in FDA warnings about adulterated supplements, and muscle-building products are often spiked with steroids (Tucker et al., 2018).
Tongkat ali is not on the WADA prohibited list, but booster products are a major source of accidental positive tests. Geyer and colleagues (2004) found 14.8% of 634 supplements contained anabolic steroids not listed on the label. Under WADA's strict liability rule, athletes are responsible for anything in their sample. If you compete, use only products certified by Informed Sport or NSF Certified for Sport.
This page is not medical advice. Men with symptoms of low testosterone (low libido, erectile problems, fatigue, loss of muscle or low mood) should see a doctor for proper testing, since low testosterone can have treatable causes that a supplement would mask.
Who might benefit
Men with mildly low testosterone are the group where the data look best, but they should be diagnosed by a doctor first. For healthy men with normal levels, expect little. For strength and muscle, creatine and enough protein have far stronger evidence, alongside strength training. Ashwagandha is another herb with some hormone data and its own safety questions.
Bottom line
Tongkat ali is one of the better-studied herbal boosters, but the evidence is still small, heterogeneous and largely based on one branded extract, with clear effects only in men with low testosterone. EFSA's safety concern and documented contamination add real risk, and it will not raise VO2max. See the other testosterone boosters we review and how to improve VO2max for what works.
Frequently asked questions
What are the benefits of tongkat ali?
The best evidence is a modest rise in testosterone in men whose levels are low. Small trials also report better mood and stress hormones and better handgrip strength in older adults, but these are short, small and mostly test one branded extract.
Does tongkat ali increase testosterone?
In a 2022 meta-analysis of five randomised trials, it raised total testosterone overall, mainly in men with hypogonadism. In healthy men the increase was not statistically significant.
Is tongkat ali safe?
Short trials report few side effects, but EFSA concluded in 2021 that its safety is not established because a root extract showed DNA damage in lab tests. Some products have contained mercury, lead or the drug sildenafil.
Does tongkat ali improve endurance or VO2max?
No trial shows it raises VO2max or improves endurance performance. Training, sleep and enough food matter far more.
Sources
- Leisegang K, Finelli R, Sikka SC, Panner Selvam MK. Eurycoma longifolia (Jack) improves serum total testosterone in men: a systematic review and meta-analysis of clinical trials. Medicina (Kaunas). 2022;58(8):1047.
- Talbott SM, Talbott JA, George A, Pugh M. Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects. J Int Soc Sports Nutr. 2013;10:28.
- Henkel RR, Wang R, Bassett SH, et al. Tongkat Ali as a potential herbal supplement for physically active male and female seniors: a pilot study. Phytother Res. 2014;28(4):544–550.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens. Safety of Eurycoma longifolia (Tongkat Ali) root extract as a novel food pursuant to Regulation (EU) 2015/2283. EFSA Journal. 2021;19(12):6937.
- Ang HH, Lee KL. Contamination of mercury in tongkat Ali hitam herbal preparations. Food Chem Toxicol. 2006;44(8):1245–1250.
- Tucker J, Fischer T, Upjohn L, Mazzera D, Kumar M. Unapproved pharmaceutical ingredients included in dietary supplements associated with US Food and Drug Administration warnings. JAMA Netw Open. 2018;1(6):e183337.
- Geyer H, Parr MK, Mareck U, Reinhart U, Schrader Y, Schänzer W. Analysis of non-hormonal nutritional supplements for anabolic-androgenic steroids: results of an international study. Int J Sports Med. 2004;25(2):124–129.