Supplement
Tongkat Ali (Eurycoma longifolia)
Total testosterone in men with low testosterone.
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
Tongkat ali is a root from Southeast Asia sold to raise testosterone. In men with low testosterone, small studies of root extracts found that levels rose. The studies did not agree well with each other, and the largest was paid for by a maker. A higher hormone level is a blood number. It is not the same as feeling or functioning better.
As studied, and the trials
Leisegang et al. (2022; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 36013514) pool 5 randomized trials: total testosterone higher (SMD 1.35) with I-squared about 87 percent, significant in men with low testosterone and not in healthy men. The largest placebo-controlled trial (Chinnappan et al., 2021; PMID 34262417; 105 men, 12 weeks) was funded and co-authored by the extract's maker. The record's original citation (Leitao et al., 2021; PMID 33541567) tested the extract with and without concurrent training and found the largest gains with both, so it does not isolate the extract. Chan et al. (2021; PMID 33559971) is a 2-week trial in healthy young men. Inconsistent, small, largely maker-run evidence on a hormone level: C. Morgado et al. (2024; PMID 37697053) rate it possibly effective in late-onset hypogonadism.
Read the grade that matches your goal. How EBL grades by use →
- Dose studied
- 200 mg/day
- Form graded
- Standardized Eurycoma longifolia (eurycomanone)
- Evidence behind the C
- PMID 34262417 →PMID 36013514 →PMID 33541567 →PMID 33559971 →
A letter describes the human evidence, not the product, the manufacturer, or the ingredient's worth.
See the full evidence record →Total testosterone in men with low testosterone, a hormone level, on small trials of standardized root extracts, the largest maker-funded.
As studied: dose, form, population and duration for every use
A grade describes the intervention that was tested. Where the product on the shelf differs from it, this says so.
The trial that would change this grade.
A positive trial of this shape, supported by further trials, would move this entry to B.
Why the current trials fall short
The letter rests on a hormone level; an independent replication The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. at adequate size would reach the surrogate cap.
Why people believe itTwo human sources; no published case reports of benefit; two reports of harm.
The case for tongkat ali, a Southeast Asian root, is that it raises testosterone. Small trials, some funded by an extract maker, found higher testosterone in men with low levels, and it is widely sold to men for energy and sexual function.
What supporters point to, and what each source actually shows. None of it is enough to move this letter higher; the trial described above under Evidence wanted is what would.
- Human trial, blood or body markerIn 32 healthy young men, 600 mg a day for two weeks raised testosterone compared with placebo An inactive substitute made to look like the real treatment, so participants cannot tell which one they received.. A hormone level over two weeks, in men without low testosterone. PMID 33559971
- Human trial, a different useIn 45 men with symptoms of low testosterone, 200 mg a day for 6 months improved erectile function scores, most when combined with exercise training. A different use, scored by the men themselves, and the trial had no exercise-only comparison. PMID 33541567
A case report describes what happened to one or a few patients. It cannot show the treatment caused the change, and reports of success are published more often than reports of failure.
A PubMed search in October 2026 found no published case report of benefit for this use.
- A 71-year-old man developed a fast, irregular heart rhythm, atrial flutter, after starting tongkat ali, and no other cause was found. The authors call the link probable. PMID 41080360
- A 47-year-old man developed jaundice and liver injury shortly after starting tongkat ali and improved after stopping it. PMID 38646387
Searched PubMed, October 2026: 2 case report record(s) returned. Both records describe harm and are listed. None describes benefit.
How this letter has changed · latest: October 2026 · Corrected
The record rested on Leitao et al. (2021; PMID 33541567) described as affecting testosterone-related measures; that trial's primary outcome was erectile function and its largest gains were in the extract-plus-training arm, so it does not isolate the extract. The use is now named as total testosterone in men with low testosterone, following Leisegang et al. (2022; PMID 36013514), whose pooled rise is significant in that group and not in healthy men. Added: Chinnappan et al. (2021; PMID 34262417), the largest placebo-controlled trial, funded and co-authored by the extract's maker, stated beside the letter; Chan et al. (2021; PMID 33559971); Morgado et al. (2024; PMID 37697053); Kotirum et al. (2015; PMID 26365449). A dose field now states the standardized water extracts at 100 to 600 mg/day, and the track field no longer names product brands. C unchanged. Applied the written grade definition under the editor's standing instruction of October 2026 (Arnold Sandlow, D.C.).PMID 26365449 PMID 33541567 PMID 33559971 PMID 34262417 PMID 36013514 PMID 37697053
Every change to a letter on this site is dated and published. The full evidence log →
Commercial disclosure
EBL earns no commission on any supplement it grades. A purchase made through the dispensary link below pays EBL nothing, the practitioner discount goes to you in full. The dispensary is Fullscript, a practitioner dispensary, and many of the professional-grade brands in it are sold mainly through practitioners rather than in health food stores. Grades are assigned by published rubric before any commercial relationship exists and are never influenced by one. Full disclosure.
As studied: standardized water extracts of the root, 100 to 600 mg/day; 200 mg/day for 6 months in the cited exercise trial, 100 or 200 mg/day for 12 weeks in the largest testosterone trial. Results do not transfer to unstandardized root powders sold under the same name.
Standardized extracts/forms were used in the cited trials; product quality varies.
The summary of the cited 6-month trial does not state a time of day or whether doses were taken with food (PMID 33541567).
Checked against the published summary; the full paper could not be read. What the cited trials did, not a schedule. Every supplement, by trial timing →
Hormone-sensitive conditions, including prostate cancer. Pregnancy. Products vary widely in extract standardization and heavy-metal contamination has been reported in this category.
Testosterone therapy and other hormonal medication: the studied effect is on the androgen axis, so the concern is additive rather than opposing. Antihypertensives and diabetes medication: additive lowering has been reported. These are mechanistic cautions; no human interaction study has measured them.
Mechanism-based, no human interaction study located. The drug interactions described for Tongkat Ali (Eurycoma longifolia) are mechanism-based. A PubMed search for human interaction, pharmacokinetic or co-administration studies pairing it with antihypertensive, testosterone returned no results in August 2026. The caution stands on pharmacology, not on a trial, and is labeled as such. Basis: pharmacological mechanism, not a human study. Searched PubMed in August 2026: 2 queries, 0 human results.
Total and free testosterone at baseline and 12 weeks, the primary endpoints The one outcome a trial names in advance as its main test. Results on other outcomes carry less weight. of the trials, with SHBG. The positive trials used standardized water extracts of the root, not unstandardized powders.
Primary evidenceSix papers, each linked to its PubMed record.
Leitao et al. (Maturitas, 2021; PMID 33541567): 45 men with androgen deficiency of aging, four arms of placebo, 200 mg/day extract, concurrent training, or both for 6 months; the primary outcome was erectile function (IIEF-5) with the Aging Male Scale and total testosterone alongside, and the largest gains were in the extract-plus-training arm; the design does not isolate the extract's effect on testosterone. Chinnappan et al. (Food Nutr Res, 2021; PMID 34262417): 105 men aged 50 to 70 with testosterone below 300 ng/dL, 100 or 200 mg/day of a standardized water extract or placebo for 12 weeks; total testosterone rose, the primary endpoint; funded by the extract's maker, with two of its employees among the authors. Chan et al. (Andrologia, 2021; PMID 33559971): 32 healthy young men, 600 mg/day for 2 weeks; testosterone and free testosterone rose against placebo; university funded. Leisegang et al. (Medicina (Kaunas), 2022; PMID 36013514): meta-analysis of 5 randomized trials; pooled standardized mean difference 1.35 for total testosterone with I-squared about 87 percent, confirmed in the hypogonadal subgroup and not significant in healthy men. Morgado et al. (Int J Impot Res, 2024; PMID 37697053): systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. of testosterone boosters rating this extract possibly effective in late-onset hypogonadism. Kotirum et al. (Complement Ther Med, 2015; PMID 26365449): meta-analysis of 2 randomized trials on erectile function, no overall difference. Grade C: small, inconsistent and largely maker-run evidence on a hormone level, positive in men with low testosterone and not in healthy men.
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These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. The grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
Who responds: this record's trial reading reports no subgroup that identifies who responds.
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How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("Eurycoma longifolia"[tiab] OR "tongkat ali"[tiab]) AND testosterone[tiab] AND (randomized controlled trial[pt] OR meta-analysis[pt] OR placebo[tiab]) AND humans[mesh]Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →