Tongkat Ali

Eurycoma longifolia Jack was described by the botanist William Jack (1795–1822) in Malayan Miscellanies, printed at Bencoolen (now Bengkulu) on Sumatra in 1822, according to the International Plant Names Index. Kew’s Plants of the World Online (POWO) accepts the name, places it in Simaroubaceae within the order Sapindales, and recognizes two subspecies, subsp. longifolia and subsp. eglandulosa. POWO gives the native range as Borneo, Cambodia, Laos, Peninsular Malaysia, Myanmar, the Philippines, Sumatra, Thailand, and Vietnam. Local names reviewed by Rehman and colleagues (Molecules 2016) include tongkat ali and Malaysian ginseng in Malaysia, pasak bumi or bedara pahit in Indonesia, ian-don in Thailand, and cay ba benh in Vietnam, and LiverTox adds Long Jack and “natural Viagra.” The name tongkat ali is not unique: Rehman and colleagues note that at least three other plants, including Polyalthia bullata and a Goniothalamus species, share it locally, one reason that DNA testing of commercial products matters.

Rehman and colleagues describe a tall, slender, shrubby tree that grows in sandy soil. Its pinnately compound leaves can reach 1 m long, with numerous opposite or nearly opposite leaflets, lance-shaped to broadly lance-shaped, 5 to 20 cm long and 1.5 to 6 cm wide, with smooth edges. The flowers are tiny, reddish, and either male or female, packed densely together, and the fruits are ovoid drupes (stone fruits) 1 to 2 cm long with a distinct ridge, turning dark reddish brown when ripe. The medicinal part is the long, twisted root. The same review estimates that collectors harvest about 21,000 kg a year against a demand of more than 54,000 kg, notes that the species’ genetic diversity is falling because of widespread harvesting, and reports that it is now planted in Malaysia partly to conserve wild stands. EFSA’s 2021 assessment describes one commercial extract as made from dried root chips of wild plants identified by DNA fingerprinting.

LiverTox counts more than 65 compounds in Eurycoma longifolia extracts, including glycosaponins, quassinoids (eurycomanone, eurycomanols, and eurycomalactones), canthin-6-one alkaloids, phenolic compounds, a coumarin, tannins, and triterpenes. Quassinoids are bitter, degraded triterpenes found only in part of the quassia family, and Rehman and colleagues describe them as the major share of the root’s chemistry; eurycomanone, also called pasakbumin-A, is the one most often used to standardize extracts. Hot-water extracts, by contrast, consist mostly of proteins, polysaccharides, and glycosaponins. Chinnappan and colleagues (Food and Nutrition Research 2021) give the specification for Physta as 0.8 to 1.5% eurycomanone, at least 22% protein, 30% polysaccharide, and 40% glycosaponin, and EFSA notes that this matches a Malaysian national standard for the extract published in 2011. Marketers call the protein and peptide fraction “eurypeptides”; Talbott and colleagues (Journal of the International Society of Sports Nutrition 2013) cite extracts standardized to 22% eurypeptides. Products vary enormously: the extract in one Malaysian drug interaction study contained only 0.027% eurycomanone, while a capsule in a 2025 case report was labeled at 2%.

Tongkat ali’s reputation comes from the forest medicine of the Malay Peninsula, Sumatra, and Borneo. Rehman and colleagues summarize its traditional uses: the root is boiled into a water decoction and taken as an aphrodisiac and for intermittent fever (malaria), lumbago, indigestion, fever, and jaundice, and as a strengthening tonic after childbirth; decoctions of the leaves are used to wash itchy skin, the fruits for dysentery, the bark against intestinal worms, the taproot for high blood pressure, and the root bark for diarrhea and fever. LiverTox adds diabetes, rheumatism, asthma, and depression to the list. The name, “Ali’s walking stick,” is said to refer to its aphrodisiac reputation, although some authors trace it to the long, twisted roots. Bhat and Karim (Fitoterapia 2010) describe the plant as used traditionally for malaria, as an aphrodisiac, and for diabetes, infections, and fever, and laboratory work in the 1990s found that its quassinoids were active against chloroquine-resistant Malaysian malaria parasites in the test tube.

Western botany named the tree in 1822, when William Jack published Eurycoma longifolia. Its commercial history is far more recent. In 1992 Malaysia brought traditional medicines into the third phase of its drug registration system, with an emphasis on quality and safety that included heavy metals, and pharmacy researchers at Universiti Sains Malaysia used that framework in the early 2000s to survey tongkat ali products for mercury and lead. A Malaysian national standard for the standardized water extract followed in 2011, and the government helped fund research, including a 2018 trial supported by a grant scheme under the Ministry of Agriculture and Agro-Based Industry. Low and colleagues (Journal of Ethnopharmacology 2013) noted teas, coffees, and carbonated drinks premixed with the root extract, and by 2016 Rehman and colleagues counted more than 200 Eurycoma longifolia products registered with Malaysia’s National Pharmaceutical Control Bureau, where it is sold as a traditional herbal medicine.

Exports turned tongkat ali into a global “testosterone booster.” EFSA records that the standardized water extract has been on international markets since 2009, and Physta also appears under the name LJ100: the typeset journal version of the 2012 Ismail trial calls the extract “LJ100/Physta.” LiverTox describes recent popularity in the United States, where root extracts are promoted to raise testosterone and improve athletic performance, and Balasubramanian and colleagues (Journal of Sexual Medicine 2019) found tongkat ali among the most popular ingredients in the six top-ranked erectile dysfunction supplements on Amazon. Wahab and colleagues (International Journal of Environmental Research and Public Health 2022) rated 321 websites about tongkat ali as generally low in quality; the most common claims were raising testosterone (37.7%), treating malaria (34.9%), and improving libido (33.6%). When an applicant sought authorization to sell the extract as a food supplement in the European Union, EFSA concluded in 2021 that its safety had not been established. Fadogia agrestis, a West African shrub also sold in supplements and sometimes weighed against tongkat ali, has as far as we could find been studied only in rats.

The leading theory is that tongkat ali nudges the body’s own testosterone production, but the human evidence for how is limited. In laboratory work, Low and colleagues (Journal of Ethnopharmacology 2013) found that eurycomanone increased testosterone output from isolated rat testis cells (Leydig cells), apparently by blocking aromatase, the enzyme that converts testosterone to estrogen, and at high concentrations by inhibiting phosphodiesterase enzymes. People do not respond so neatly. In a placebo-controlled study by Chan and colleagues (Andrologia 2021), 32 young men took 600 mg a day for two weeks: total and free testosterone rose, but so did estradiol, an estrogen, while the pituitary hormones that drive the testes, luteinizing hormone and follicle-stimulating hormone, did not change. LiverTox summarizes the human studies as showing mild rises in total testosterone without increases in free testosterone or sex hormone-binding globulin (the protein that carries testosterone in the blood), and in the largest trial free testosterone did not differ from placebo.

Other proposed mechanisms rest on laboratory and animal work. Rehman and colleagues describe the “eurypeptides” of water extracts as complex polypeptides said to boost androgen production through dehydroepiandrosterone (DHEA) and to lower sex hormone-binding globulin, but we found no human study that tested this fraction on its own, and in the largest Physta trial DHEA rose within the treated groups without differing from placebo. Tee and colleagues (BioMed Research International 2016) found that a solvent fraction of the root relaxed rat aortas and inhibited angiotensin-converting enzyme, the target of a common class of blood pressure drugs, in the test tube. Tsai and colleagues (Nutrients 2020) reported that powdered root, given by mouth for eight weeks, lowered blood sugar in diabetic mice. A standardized quassinoid mixture slowed the growth of human prostate cancer cells in culture and, by injection, in mice (Tong and colleagues, PLoS One 2015). None of these effects has been shown in people, and the blood pressure and blood sugar findings matter mainly as possible interaction risks.

Little is known about how the body handles tongkat ali. In rats, Rehman and colleagues report that eurycomanone given by mouth reached much lower blood levels than an injected dose, even at five times the amount, peaking about 4.4 hours after dosing. Animal studies show low acute toxicity: the dose that kills half the animals was 1,500 to 2,000 mg/kg for an alcohol extract and more than 3,000 mg/kg for a water extract in mice. Low and colleagues (Phytotherapy Research 2014) saw no toxic signs in pregnant rats given a quassinoid-rich extract, whose offspring were normal, and set a no-observed-adverse-effect level of 100 mg/kg a day. EFSA, however, highlighted genetic toxicity. The extract caused chromosome damage in human cells in the test tube, and in a follow-up animal test it damaged DNA in the stomach and duodenum, the tissues it touches first, at 2,000 mg/kg, an effect EFSA judged was due to genotoxicity rather than general cell damage. For athletes, Chen and colleagues (International Journal of Preventive Medicine 2014 and 2019) found that 200 to 400 mg a day did not change the urinary testosterone-to-epitestosterone ratio used in doping tests.

Testosterone is the main reason people buy tongkat ali, and the evidence shows a modest rise, mainly in men with low levels. Leisegang and colleagues (Medicina 2022) found nine studies, seven of which used Physta, and pooled five randomized trials in 232 men: total testosterone rose with a large standardized mean difference of 1.35, but heterogeneity was high (87%), tests suggested publication bias, and in men with normal levels the pooled rise was not statistically significant. The review itself received no external funding. Its largest trial, by Chinnappan and colleagues (Food and Nutrition Research 2021), randomized 105 men aged 50 to 70 with total testosterone under 300 ng/dL to Physta 100 mg, 200 mg, or placebo for 12 weeks. On 200 mg, average testosterone went from 200.5 to 225.0 ng/dL against 183.0 to 177.9 on placebo, and fatigue and aging-symptom scores improved; free testosterone did not differ between groups. Biotropics Malaysia funded the trial and two authors were its employees. An earlier uncontrolled study by Tambi and colleagues (Andrologia 2012) gave 200 mg a day for a month to 76 of 320 men with late-onset hypogonadism and reported better symptom and testosterone scores. A urology review of testosterone boosters by Morgado and colleagues (International Journal of Impotence Research 2024) judged tongkat ali “possibly effective” for men with late-onset hypogonadism and healthy men, based on three studies. Verdict: a small, real-looking effect on total testosterone in men with low levels, from mostly sponsor-funded trials of one extract, and no substitute for a medical diagnosis.

Libido and erectile function results are mixed. Kotirum and colleagues (Complementary Therapies in Medicine 2015) found only two eligible placebo-controlled trials, with 139 men; overall, scores on the five-item International Index of Erectile Function did not improve significantly (a difference of 0.91 points, with a confidence interval running from −1.50 to 3.33), although men who started with worse function improved by about 2 points. In the main Physta trial, Ismail and colleagues (Evidence-Based Complementary and Alternative Medicine 2012) gave 300 mg a day or placebo to 109 men aged 30 to 55 for 12 weeks and reported better erectile function and physical functioning scores and 14% higher libido scores by week 12, although testosterone did not change compared with placebo; Biotropics funded the trial and two authors were employees. A trial of Physta combined with Polygonum minus, another Malaysian herb, reported better erection hardness, but only 26 men completed it and three of the five authors worked for Biotropics (Udani and colleagues 2014). In a six-month Brazilian trial of 45 men with symptoms of androgen deficiency, Leitão and colleagues (Maturitas 2021) found the best erectile scores with 200 mg of tongkat ali plus exercise training. Verdict: possible small benefits in men with existing problems, not reliable enough to rely on.

Fertility claims rest largely on uncontrolled studies. Tambi and Imran (Asian Journal of Andrology 2010) gave 200 mg a day of a standardized extract to 350 men with unexplained infertility, but only 75 completed three months; in those men, semen volume, sperm concentration, normal shapes, and motility improved, and 11 partners (14.7%) became pregnant. There was no control group, and losing nearly four in five participants makes the results hard to interpret. In the Ismail trial, semen was analyzed in only 36 men; in a subgroup of 11 with low starting values on tongkat ali, motility rose from 33.8% to 48.8%, while in the placebo group it rose from 36.3% to 44.6%, a change that was not statistically significant. Erasmus and colleagues (Andrologia 2012) found no harm to human sperm exposed to the extract in the test tube at concentrations like those reached in use, though very high concentrations may be harmful. Verdict: interesting but very weak. A couple having difficulty conceiving needs a medical evaluation of both partners, and a supplement should not delay it.

Stress and mood rest on one small, company-funded trial. Talbott and colleagues (Journal of the International Society of Sports Nutrition 2013) gave Physta 200 mg a day or placebo for four weeks to moderately stressed adults. Among the 63 analyzed, 32 men and 31 women, tension fell by 11%, anger by 12%, and confusion by 15% compared with placebo, salivary cortisol was 16% lower, and salivary testosterone 37% higher. Biotropics Malaysia funded the study, which was run by SupplementWatch; one author worked for Biotropics and another for a company selling a tongkat ali stress product. A longer trial by George and colleagues (Food and Nutrition Research 2018), funded by a Malaysian government grant with a Biotropics employee as lead author, gave tongkat ali with multivitamins or placebo to 93 people for 24 weeks and found no significant overall differences between groups in quality of life, mood, or stress, only improvements within the treated group and in a few age subgroups. Verdict: not established, and resting almost entirely on research connected to one manufacturer.

Sports performance trials have been mostly disappointing. LiverTox concludes that rises in testosterone have been linked to mild gains in strength alongside resistance training but not to better athletic performance. Chen and colleagues (International Journal of Preventive Medicine 2019) assigned 40 young men to placebo, 200 mg a day of tongkat ali, resistance training, or both for eight weeks; training improved leg power with or without the herb, and the herb alone did not. Zakaria and colleagues (Biology of Sport 2023) gave 400 mg a day or placebo to 18 rugby sevens players for a week before a damaging leg-press session and found no difference in force, jump performance, soreness, muscle-damage markers, or salivary testosterone or cortisol. A small study by Henkel and colleagues (Phytotherapy Research 2014) reported stronger handgrips and higher testosterone in 25 active older men and women after five weeks of 400 mg a day, but it had no placebo group. Verdict: no convincing benefit for strength, endurance, or recovery in trained people, and products sold for bodybuilding carry extra contamination risks.

Traditionally the root is boiled into a bitter water decoction. Modern products include raw root powder, root chips, capsules of crude powder or extract, and instant coffees and teas premixed with the extract; Rehman and colleagues counted more than 200 Eurycoma longifolia products registered in Malaysia. LiverTox gives the typical dose in traditional medicine as 100 to 400 mg a day and notes that capsules sold online for testosterone and bodybuilding offer 1,000 to 1,600 mg. Those figures are not comparable, because a milligram of raw root powder is not a milligram of concentrated extract. A drug-to-extract ratio, such as the 20:1 stated for Physta in one trial, describes how much dried root went into the extract but not which compounds it contains, and we found no published trials of most retail products.

Almost all clinical data come from standardized hot-water extracts, most often Physta, a freeze-dried extract standardized to 0.8 to 1.5% eurycomanone with set levels of protein, polysaccharide, and glycosaponin. Trials we reviewed used 100 to 600 mg a day for one week to six months: 200 mg in the largest testosterone trial and the stress trial, 300 mg taken as four 75 mg capsules in the main sexual-function trial, 400 mg in most sports studies, and 600 mg for two weeks in young men. The applicant to EFSA proposed up to 200 mg a day for adults, excluding pregnant and breastfeeding women, but EFSA did not accept that the extract was safe at any intake. We found no regulator that has set a recommended medicinal dose, and results from Physta cannot be assumed to apply to other extracts, root powders, or coffee blends.

Quality is the biggest practical problem. Abubakar and colleagues (Pharmaceutical Biology 2018) used DNA barcoding on tongkat ali herbal products and found only 37% authentic and 27% adulterated, and one product that passed the DNA test lacked the expected marker compound, eurycomanone. Surveys by Ang and colleagues in Malaysia found mercury above the national 0.5 ppm limit in 36 of 100 tongkat ali products in 2004 and in 26 of 100 “tongkat ali hitam” products in 2006, and lead above the limit in eight of 100 herbal products in 2003, all eight sold under tongkat ali or Eurycoma names. Singapore’s Health Sciences Authority recalled “XP Tongkat Ali Supreme” in 2009 after finding tadalafil in its capsule shells, and Said and colleagues (Food Chemistry 2014) found that two of ten Eurycoma products, both bought online, had infrared spectra closely matching a sildenafil medicine, suggesting a hidden sildenafil-like drug. The US Food and Drug Administration (FDA) warns that many “male enhancement” and stamina products contain dangerous hidden ingredients and that its list of tainted products covers only a fraction of them. Anyone who still chooses tongkat ali should prefer a single-ingredient product with independent testing for identity, heavy metals, and drug adulterants.