Tongkat ali is the root of Eurycoma longifolia, a slow-growing tree from Southeast Asia that has been used in traditional medicine for centuries. The strongest human evidence is for a rise in total testosterone in men: a 2022 meta-analysis of five randomized trials found a significant increase, and it was clearest in men who started with low testosterone. Claims about erections, stress, muscle and fertility rest on a handful of small trials, and their results are mixed.
Quick facts about tongkat ali
| Feature | What the studies show |
|---|---|
| Form studied | A standardized water extract of the root. The 2022 review says most trials used one freeze-dried water extract standardized to 0.8 to 1.5% eurycomanone. |
| Doses in studies | 100 to 600 mg a day |
| Study length | From 3 days to 6 months |
| Main studied uses | Testosterone in men, erectile function, stress and mood, strength and body composition, semen quality |
| Strongest human evidence | Testosterone in men, from a 2022 meta-analysis of five randomized trials |
| Results are mixed for | Erectile function, strength and body composition. Evidence for fertility is limited. |
What the human evidence shows, strongest first
Two terms come up below. A randomized trial assigns people to the extract or to a placebo by chance. A meta-analysis pools the results of several trials into one statistical summary. Our guide, ingredient evidence vs marketing claims, explains these designs in more detail.
Testosterone in men
The 2022 systematic review and meta-analysis in 2022 systematic review and meta-analysis looked at nine studies of Eurycoma longifolia and testosterone in men. It pooled five randomized trials with 232 men. The pooled result was a significant rise in total testosterone in men taking the extract (standardized mean difference 1.35, 95% CI 0.57 to 2.14, p = 0.001). A standardized mean difference lets studies that measure differently be compared. The 95% confidence interval shows the uncertainty around the estimated average effect.
The rise was significant in men with low testosterone, defined in the review as under 300 ng/dL. It was not significant in men with normal levels. The authors say the results support a possible use for raising testosterone, and that more research is needed before clinical use.
Here is what each trial in that review reported:
| Trial | Men studied | Dose and length | What it reported |
|---|---|---|---|
| Leitão 2021, double-blind randomized trial | Men aged 40 to 59 with androgen deficiency, 9 on extract and 12 on placebo | 200 mg a day for up to 6 months | Testosterone rose from 278.2 to 400.3 ng/dL on extract. The placebo group went from 281.5 to 258.5 (p less than 0.05). |
| Chinnappan 2021, double-blind multicenter randomized trial | Healthy men aged 50 to 70, 35 per group | 100 mg or 200 mg a day for up to 12 weeks | Significant difference from placebo in men starting under 300 ng/dL. In the 200 mg arm, testosterone rose from 200.5 to 225.0 ng/dL, and placebo went from 183.0 to 177.9. |
| Chan 2021, randomized trial | Young men aged 18 to 30 | 600 mg a day for 2 weeks | Testosterone rose within the extract group (802 to 924 ng/dL). The review notes no between-group comparison was reported. |
| Quin 2021, doctoral thesis | Sedentary young men | 600 mg a day for 2 weeks and for 8 weeks | The 2-week arm rose. The review says the 8-week arm showed no improvement. |
| Ismail 2012, randomized trial | Healthy married men aged 30 to 55 | 300 mg a day for 12 weeks | No difference from placebo in testosterone. |
| George 2013, randomized trial | Healthy men | Not stated in the review | No difference from placebo in testosterone. |
| Tambi 2012, before-and-after study | 76 men with hypogonadism or late-onset hypogonadism | 200 mg a day for up to 1 month | Testosterone rose from 163 to 240 ng/dL. The review’s table lists no placebo group. |
A 2013 study described below also reported a 37% rise in testosterone in saliva. Its authors suggest the extract may free more testosterone from sex hormone-binding globulin (SHBG), the protein that binds testosterone in the blood. The paper says the exact mechanism is unknown.
Erectile function
The 2015 meta-analysis in 2015 erection meta-analysis pooled two randomized trials with 139 participants. It measured erections with the IIEF-5, a five-question score. Across all men, the difference from placebo at week 12 was not significant (weighted mean difference 0.91, 95% CI -1.50 to 3.33). In men who started with lower scores, the improvement was 2.15 points (95% CI 1.03 to 3.27). That improvement was not seen in men who started with higher scores. The authors wrote that the extract ‘may have clinical effect on erectile function’ and that more efficacy trials are warranted.
Is tongkat ali like prescription erection pills?
No. Tongkat ali is a root extract sold as a supplement, not a prescription drug. The 2013 study paper names tadalafil, sildenafil and vardenafil as prescription erectile dysfunction drugs. It also says some products labeled Eurycoma longifolia contained none of the root and were spiked with those drugs. Tongkat ali is not a substitute for prescribed treatment, so take erection problems to a clinician.
Stress, cortisol and mood
The 2013 study appeared in the 2013 mood and hormone study in the Journal of the International Society of Sports Nutrition. It randomized 64 adults with moderate stress to 200 mg a day of a standardized hot-water root extract or placebo for 4 weeks. 63 finished. Men and women were reported together. The study was funded by the company that makes the extract, and one author works for a company that makes tongkat ali extract. The authors conclude that daily supplementation ‘improves stress hormone profile and certain mood state parameters.’
| Measure after 4 weeks | Extract compared with placebo |
|---|---|
| Salivary cortisol (stress hormone) | 16% lower |
| Salivary testosterone | 37% higher |
| Cortisol to testosterone ratio | 36% lower |
| Tension | 11% lower |
| Anger | 12% lower |
| Confusion | 15% lower |
| Depression, vigor, fatigue | No difference between groups |
| Overall mood | 3% better, not significant (p = .083) |
Strength, body composition and women
The 2013 paper describes earlier trials. In young men, 100 mg a day with strength training gave greater gains in fat-free mass and one-rep-max strength over 8 weeks. In middle-aged women aged 45 to 59, 100 mg a day with twice-weekly strength training for 12 weeks increased fat-free mass more than placebo did.
Healthline’s tongkat ali review describes a 2014 trial of 25 active older adults. They took 400 mg a day for 5 weeks and gained more muscle strength than placebo. Healthline suggests the effects may depend on dose and length of treatment.
Semen quality and fertility
The 2022 review cites a 2010 study of infertile men. It reports better semen quality over 9 months and a rise in spontaneous pregnancies. Healthline summarizes the same 2010 study differently: 200 mg a day for 3 months in 75 male partners of couples with infertility, with better sperm concentration and motility and pregnancy in over 14% of couples. The two accounts give different durations, so treat the details as unsettled.
Doses used in studies
These are the amounts researchers gave, per day, in the studies above. They are not a recommendation.
| Daily dose | Study | Men or people studied | Length |
|---|---|---|---|
| 100 mg | Chinnappan 2021 | Healthy men aged 50 to 70 | Up to 12 weeks |
| 200 mg | 2013 mood and hormone study | Adults with moderate stress | 4 weeks |
| 200 mg | Leitão 2021 | Men aged 40 to 59 with androgen deficiency | Up to 6 months |
| 200 mg | Tambi 2012 | Men with hypogonadism or late-onset hypogonadism | Up to 1 month |
| 300 mg | Ismail 2012 | Healthy married men aged 30 to 55 | 12 weeks |
| 400 mg | Henkel 2014 | Older male cyclists aged 57 to 72 | 3 and 5 weeks |
| 600 mg | Chan 2021 | Young men aged 18 to 30 | 2 weeks |
| 600 mg | Quin 2021 | Sedentary young men | 2 and 8 weeks |
Tongkat ali side effects and safety
What EFSA concluded about safety
The European Food Safety Authority (EFSA) published a EFSA’s 2021 safety opinion on a standardized water extract of the root, submitted as a novel food. It was adopted on 27 October 2021. The panel concluded that the safety of this extract ‘has not been established under any condition of use.’ EFSA assessed risk only, not benefit. The proposed use was up to 200 mg a day for adults, excluding pregnant and breastfeeding women.
EFSA’s concern was DNA damage. A chromosome test in human cells was positive. In a rat test at 2,000 mg/kg body weight a day, DNA damage appeared in the stomach and duodenum. A 12-month rat study showed stomach changes at 1,000 mg/kg a day. EFSA also said the human studies it reviewed were designed to test benefits and measured only a few safety outcomes.
Is tongkat ali hard on your kidneys?
The answer is mixed. Healthline says a 2016 review found no liver or kidney changes in mice given specified weight-based doses of tongkat ali extract. The 2013 paper describes a two-month trial in 20 healthy men taking 600 mg a day, with no effect on liver or kidney measures. But EFSA notes that the advisory committee that first reviewed the application raised concern about adverse effects, especially in the liver and kidneys, in a submitted 2015 chronic rat study.
Side effects reported in studies
| Effect | Where it was reported | Detail |
|---|---|---|
| Unusual fatigue | 2013 mood and hormone study | Three subjects in the first two weeks, two on extract and one on placebo. No other side effects were reported. |
| Stomach upset and itching | Chinnappan 2021, as reported in the 2022 review | The review says this was the only trial it found that reported side effects. |
| Side effects in both groups | Ismail 2012, as reported in the 2022 review | Side effects occurred in both the extract and placebo groups. |
| DNA damage in stomach and duodenum | EFSA’s rat tests at high doses | Animal finding, not a trial result in people. |
| Mercury above limit | Healthline’s tongkat ali review, summarizing a 2006 study | 26% of 100 Malaysian supplements tested had mercury above the recommended limit. |
| Spiked with erection drugs | 2013 mood and hormone study | Some products labeled Eurycoma longifolia contained none of the root and were spiked with tadalafil, sildenafil or vardenafil. |
Medicine interactions
Healthline advises that people with medical conditions or who take medicines should speak with their healthcare provider before taking tongkat ali. Interactions with specific medicines are a question for your pharmacist or clinician, who can check your full medicine list before you start.
Who should talk to a clinician first
- Men who think they have low testosterone or are considering testing. The 2022 review notes that a 300 ng/dL threshold is generally recommended as the lowest limit of normal. It also says testosterone replacement is contraindicated in some men, including those with prostate cancer and those who want to preserve fertility. A clinician can order the right blood test and weigh your options.
- Anyone being treated for erection problems or taking a prescribed medicine. Tongkat ali is not a substitute for prescribed treatment.
- Pregnant or breastfeeding people. Healthline says they should not take it because research is lacking, and EFSA’s proposed use excludes them.
- Parents considering it for children. Healthline says its effects in children have not been researched.
What is still unknown
Most trials are small. Group sizes varied from small trials of about 8 to 9 men up to trials of more than 50 men per arm, such as Ismail 2012 with 54 and 55 men and the 76-man Tambi 2012 before-and-after study. The five randomized trials pooled 232 men. Results vary widely: the review’s inconsistency measure was 87%, and some trials found no change in testosterone. In men with normal levels, the pooled effect was not significant (standardized mean difference 0.76, 95% CI -0.54 to 2.06). The review’s statistics flagged possible publication bias in the low-testosterone group, which means small positive studies may be more likely to be published.
Most trials used the same commercial extract. The 2013 mood and hormone study was funded by the company that makes that extract, and one of its authors works for a company that makes tongkat ali extract. Check each other trial’s funding statement in its published paper before relying on it. The longest trial lasted 6 months. The longest animal study in EFSA’s review ran 12 months. The 2022 review cites an analysis of 41 Malaysian products. Of 24 containing eurycomanone, 11 fell within the recommended 0.8 to 1.5% range, 9 were above it, and some contained none. Ask the seller for batch test results before you buy.
How to read a label that lists tongkat ali
- Standardization. Look for the eurycomanone percentage. The recommended range in the 2022 review is 0.8 to 1.5%.
- Amount per serving. Compare the milligrams of extract with the doses in the table above. Make sure the number is for the extract itself.
- Extract type. The trials used water extracts. The 2013 paper reports toxic effects of alcohol extracts at high doses in animal tests.
- Proprietary blends. If tongkat ali sits inside a blend with a single total weight, you cannot tell how much you are getting. Ask the seller for the exact amount.
- Testing. Healthline advises looking for third-party testing, since supplements may contain more or less tongkat ali than the label lists and some have mercury.
- Coffee blends. Check the milligrams per cup or serving of extract, then compare with the doses above.
No product is named here as best. Use the label, the seller’s batch results and your pharmacist to compare options. For another herbal extract reviewed the same way, see our gymnema sylvestre benefits evidence page.
By ClinicalStudyConnect.com Research Desk