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Tongkat ali
A Southeast Asian tree used in traditional medicine. Its root extracts are now sold as supplements promoted for testosterone and athletic performance.
Explained simply · Last reviewed
What it is
Tongkat ali (Eurycoma longifolia), also known as long jack or Malaysian ginseng, is a slow-growing evergreen tree native to Southeast Asia. LiverTox, the US government's liver-injury database, says its leaves, roots and bark have been used extensively in traditional medicine for many conditions. It says the tree has recently become a popular herbal supplement in the United States, as extracts of its roots have been promoted as increasing testosterone levels and improving athletic performance.
More about Tongkat ali
LiverTox, the US government's liver-injury database, says its leaves, roots and bark have been used extensively in traditional medicine for many conditions. It says the tree has recently become a popular herbal supplement in the United States, as extracts of its roots have been promoted as increasing testosterone levels and improving athletic performance.
LiverTox reports that more than 65 compounds have been found in its extracts, including glycosaponins, quassinoids such as eurycomanone, and canthin-6-one alkaloids. LiverTox says it is not clear which of them have the claimed effects of tongkat ali. It says tongkat ali is available over the counter in forms including raw powders, blends with tea or coffee, and capsules, alone or combined with other herbal products or dietary supplements.
A 2022 review of testosterone studies reports that seven of the nine studies it describes used the same commercial freeze-dried water extract of the root.
Also known as: Eurycoma longifolia, long jack, longjack, Malaysian ginseng
At a glance
Safety: known risks and 1 group who should avoid it or take extra care. See Safety ↓Claims made about Tongkat ali, and how strong the evidence is for each:
- Raises testosterone levels in men (a blood marker)Evidence rating: Limited
- Improves erectile function in menEvidence rating: Limited
- Reduces stress or improves moodEvidence rating: Insufficient
- Improves exercise performanceEvidence rating: Insufficient
- Improves semen quality or fertility in menEvidence rating: Insufficient
Each rating follows our published rules and the sources cited for it. We don’t add our own medical judgment. How we rate
Safety
Read this before the ratings below.
Risks
- LiverTox, the US government’s liver-injury database, gives tongkat ali a likelihood score of D: a possible rare cause of clinically apparent liver injury. It reports isolated cases of clinically apparent liver injury, which it describes as recent, in people taking tongkat ali, largely young male body builders, and states that the possibility of unacknowledged anabolic steroid use weakens the evidence that the injury was due to tongkat ali. It describes the liver injury reported as self-limited, and states that chronic injury has not been clearly described.
- LiverTox states that side effects of tongkat ali at conventional doses are uncommon but may include nausea, abdominal discomfort, diarrhea, headaches and rash, and that its long-term safety has not been well documented in humans. It reports that in small, rather short clinical studies side effects were usually described as uncommon, unrelated to therapy and minimal, with no changes in liver blood tests, but that the effects of long-term use and of higher doses have not been assessed in humans. It also states that there is no standardization of the purity and concentration of the extracts used.
- European Union: the European Food Safety Authority (EFSA) assessed one standardized hot-water extract of tongkat ali root, which the company applying for its approval proposed as a food supplement for adults other than pregnant and breastfeeding women. In an opinion adopted on 27 October 2021, its expert panel concluded that the safety of the extract had not been established under any condition of use. The panel found that the extract damaged chromosomes in a laboratory test on human cells and caused DNA damage in the stomach and duodenum of rats at the highest dose tested, and concluded that it “has the potential to induce DNA damage, which is of concern, particularly locally for tissues that represent first sites of contact”.
- EFSA’s expert panel noted that the available human studies of tongkat ali extracts were designed mainly to look for benefits and addressed only a limited number of safety endpoints, not ones relevant to the toxicity profile of the standardized hot-water root extract it assessed. EFSA’s opinion states that it covers only risks from consuming the extract it assessed, under the conditions of use its applicant proposed.
- A 2022 meta-analysis on testosterone reports that only one of the studies it describes reported adverse effects linked to tongkat ali, including gastrointestinal symptoms and itching, and that another observed adverse events in both the tongkat ali and placebo groups.
Who should avoid it or take extra care
- People with liver disease: LiverTox, the US government’s liver-injury database, states that cases may be more frequent and more severe in patients with pre-existing liver disease, and that most clinical studies of tongkat ali have excluded such patients.
Safety sources: Source [1]Source [2]Source [3]
What the evidence says
Each claim is rated on its own evidence. Ratings follow the scale on our methodology page.
Raises testosterone levels in men (a blood marker) Evidence rating: Limited
Men take it hoping it will raise their testosterone levels.
A 2022 review of five small trials found higher total testosterone with tongkat ali, but the trials disagreed widely; another review’s one trial found no significant rise.
Testosterone is a blood marker, and this page reports a change in it as a marker, not as a health benefit. A 2022 systematic review and meta-analysis pooled five randomized trials in men. It found a significant increase in total testosterone with tongkat ali compared with control. Its authors conclude that their analysis highlights the possible use of tongkat ali for enhancing testosterone production, and that more research is required before its use in clinical practice.
The authors also report limitations. The five trials had limited sample sizes and differed in design, population, amount and length of treatment. Their results disagreed substantially (an I-squared of 87%). A statistical test indicated publication bias, and two trials were entered twice, once for each treatment group. Split by starting level, the increase was significant in men whose testosterone was low. But that group rests on two trials, each entered twice, whose results disagreed substantially (an I-squared of 89%), and the authors report significant publication bias among them. In three trials of 88 men with normal levels, the increase was not significant. That is too little evidence to show an effect in them, not evidence that there is none.
A 2021 systematic review of herbs and testosterone found one randomized trial of tongkat ali, in 109 men aged 30 to 55 over twelve weeks. It reports no significant increase in testosterone compared with placebo. LiverTox, the US government’s liver-injury database, states that several studies in humans have shown mild increases in serum total testosterone, usually needing several weeks for a full response, with no rise in free testosterone or sex hormone binding globulin. The 2022 meta-analysis reports that three of the six studies it describes that measured free testosterone found a significant rise within the tongkat ali group, against starting levels rather than placebo; other studies reported no significant improvement.
Neither review reports GRADE certainty. With few small trials that disagree, this page rates the claim limited.
Sources: Source [1]Source [2]Source [3]
Improves erectile function in men Evidence rating: Limited
Men with erection problems take it hoping it will improve their erections.
A 2023 review found two trials of tongkat ali that reported better erectile function scores; it gave no certainty rating and called for more trials with more participants.
A 2023 systematic review of supplement ingredients for erectile dysfunction found two randomized trials that tested tongkat ali on its own, one lasting three months and one six months. It counted both as reporting improved erectile function scores. It states that a meta-analysis was not possible for tongkat ali.
The review states that it used the GRADE approach, but it reports no certainty rating for tongkat ali or any other ingredient. Noting some risk of bias in the trials for every ingredient, its authors write that they can only state that the ingredients they identified are potentially effective in improving erectile function on average. They add that more randomized trials with more participants are needed. With two trials, of 37 and 102 men, no pooled result and no certainty rating, this page rates the claim limited.
Sources: Source [1]
Reduces stress or improves mood Evidence rating: Insufficient
People under stress take it hoping it will calm them and lift their mood.
One trial, funded by the extract’s maker, found lower tension, anger and confusion scores than with placebo, but no significant change in overall mood score.
No systematic review of tongkat ali for stress or mood was found for this page. The cited evidence is one randomized, placebo-controlled trial in which 64 adults screened for moderate stress took tongkat ali or a placebo for four weeks; 63 completed it. On a mood questionnaire, tension, anger and confusion scores improved significantly with tongkat ali compared with placebo. The trial reports no effect between the groups on depression, vigor or fatigue scores, and the change in overall mood score was not statistically significant.
Salivary cortisol was lower, and salivary testosterone higher, than with placebo. These are markers, not measures of stress or mood themselves.
The trial was funded by the manufacturer of the extract it tested and carried out by a company that received that funding. One author was employed by the manufacturer, and another by a nutrition company that uses tongkat ali as one ingredient in an anti-stress dietary supplement.
One trial is too little evidence to rate this claim either way, so it is rated insufficient. That does not mean the trial found no effect.
Sources: Source [1]
Improves exercise performance Evidence rating: Insufficient
People who train take it hoping it will make them stronger or help them perform better.
One trial of 12 athletes in the heat found no significant effect, and LiverTox says testosterone rises have been associated with mild strength gains in training, not better athletic performance.
The only review found for this page that reports a separate result for tongkat ali is a 2021 meta-analysis of supplements for endurance exercise in hot conditions. It included one tongkat ali trial: a double-blind, randomized crossover study in 12 male recreational athletes, who ran on a treadmill for an hour and then did a 20-minute time trial in the heat. The result for tongkat ali was not statistically significant, and the review notes that the original trial also found no significant difference from placebo. One trial of 12 men is too little evidence to show an effect, and it does not show that there is none.
No systematic review of tongkat ali for strength, muscle mass or body composition was found for this page. LiverTox, the US government’s liver-injury database, states that the rises in testosterone seen with tongkat ali have been generally associated with “improved symptoms” and mild increases in muscle strength in response to resistance training, but have not been linked to improved athletic performance.
LiverTox’s annotated bibliography also describes two trials that measured strength. In men with androgen deficiency, strength rose with exercise training, but there were no consistent differences when tongkat ali was added. In 18 young rugby players, there were no differences from placebo in peak force or strength. The claim is rated insufficient.
Sources: Source [1]Source [2]
Improves semen quality or fertility in men Evidence rating: Insufficient
Men trying to father a child take it hoping it will improve their sperm.
One trial with no control group reported higher sperm concentration and a higher share of normally shaped sperm than at the start, in men who all took tongkat ali.
No systematic review, meta-analysis or health authority statement reporting a result for tongkat ali on sperm or fertility could be read in full for this page. The cited evidence is one trial with no control group: every man in it took tongkat ali, and no group took a placebo or nothing. The paper describes the men as the male partners of couples with unexplained infertility, attending a clinic in Kuala Lumpur, with low sperm concentration, reduced sperm movement and abnormally shaped sperm. They took a standardized water extract of tongkat ali root, and their semen was tested every three months for up to nine months.
The paper’s methods report that 350 men were recruited and 75 met the inclusion criteria and were treated, while its summary says all 350 were given the extract and 75 completed the first three months. Of the 75, 49 completed six months and 17 completed nine. Compared with the men’s own starting values, average sperm concentration and the share of normally shaped sperm were significantly higher at each three-month check. Sperm movement was significantly higher at three months only, and the rise in semen volume was not statistically significant. The paper’s summary and conclusion describe significant improvement in all semen measures, including volume; this page reports its results section and table.
The authors report 11 pregnancies without fertility treatment among the men’s partners (14.7%) during the study, and they call for “further studies in a larger group of patients”. The paper does not say who funded the study. The authors declare “no competing commercial interests in relation to the company that produced” the extract, and state that they did not receive grant support from it.
One uncontrolled trial is too little evidence to rate this claim either way, so it is rated insufficient. That does not mean the trial found no effect.
Sources: Source [1]
Which form the evidence used
Supplements are sold in several forms. This is what the sources on this page say about them — which form the research used, and any comparison those sources themselves made. Where they made none, this page does not rank the forms.
Water extract of the root, What the sources supportDetails
The authors of a 2022 review of testosterone studies report that seven of the nine studies they describe used the same commercial freeze-dried water extract of the root, and that this limits the potential influence of other components on the results. They also report, from an analysis of 41 products sold in Malaysia, that 24 contained eurycomanone, the marker compound such extracts are standardized to; 11 of those were at what the review calls the recommended level of eurycomanone, 9 were above it, and some products contained none. No cited source compared one form of tongkat ali with another, so this page cannot say whether any form works better or is safer than another. Source [1]
Sources
- Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical TrialsMedicina, 2022 · Meta-analysis · Primary source
- Examining the Effects of Herbs on Testosterone Concentrations in Men: A Systematic ReviewAdvances in Nutrition, 2021 · Systematic review · Primary source
- Tongkat AliLiverTox: Clinical and Research Information on Drug-Induced Liver Injury, National Institute of Diabetes and Digestive and Kidney Diseases, 2024 · Health authority summary · Primary source
- Dietary Supplements for Erectile Dysfunction: Analysis of Marketed Products, Systematic Review, Meta-Analysis and Rational UseNutrients, 2023 · Meta-analysis · Primary source
- Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjectsJournal of the International Society of Sports Nutrition, 2013 · Randomized controlled trial · Supporting source
- The Effect of Dietary Supplements on Endurance Exercise Performance and Core Temperature in Hot Environments: A Meta-analysis and Meta-regressionSports Medicine, 2021 · Meta-analysis · Primary source
- Eurycoma longifolia Jack in managing idiopathic male infertilityAsian Journal of Andrology, 2010 · Trial without a placebo group · Supporting source
- Safety of Eurycoma longifolia (Tongkat Ali) root extract as a novel food pursuant to Regulation (EU) 2015/2283EFSA Panel on Nutrition, Novel Foods and Food Allergens (EFSA Journal), 2021 · Health authority summary · Primary source
Page history
Show all 4 changes to this page
- — Rewritten to the content style guideline; ratings and sources unchanged.
- — Added male fertility and semen quality, rated insufficient. No review or health authority statement on it could be read in full; the one trial cited, Tambi and Imran 2010, has no control group. No existing claim, rating or source changed. Two narrative reviews of tongkat ali and exercise were read in full and not cited, because they add no tongkat ali result a reader needs beyond the sources already cited.
- — Published. The claims, the safety section and every source passed the site's source and wording reviews over two revision rounds. The owner's decisions on unread reviews and disclosures are recorded in docs/08-open-decisions.md.
- — First drafted. Testosterone (a blood marker) rated limited and erectile function rated limited, each on systematic reviews that report no GRADE certainty; stress and mood, and exercise performance, rated insufficient. Safety section leads on the LiverTox entry and the 2021 EFSA novel-food opinion.