Tongkat ali is a root extract sold for testosterone, libido, and stress, and the small human trials support a narrow version of that. In moderately stressed adults, four weeks of a standardized root extract lowered cortisol and raised testosterone. Pooled across five randomized trials, it raised total testosterone in men, with the clearest effect in men who were older or whose testosterone was low to start with, and little to show in younger men already in the normal range. The studied dose is 100 to 400 mg a day of a standardized water extract, most often 200 mg.
The evidence is thin: the trials are small and short, several are built around one branded extract, and some are funded by its maker. Product surveys have found mercury above the limit in a third of tongkat ali products, so a third-party-tested extract matters. The herb it is usually stacked with, Fadogia agrestis, has no human trials and an animal testicular-toxicity signal.
Findings & Outcomes
What It Is
Tongkat ali is the root of Eurycoma longifolia, a tall shrub native to the rainforests of Malaysia, Indonesia, and neighboring countries, where the bitter root has a long history in traditional medicine as a tonic for energy, stamina, and male vitality. Longjack and Malaysian ginseng are other names for the same plant. The active compounds are a family of bitter molecules called quassinoids, the best known being eurycomanone, together with related steroid-like compounds. A water extraction of the root concentrates them, and raw powder does not. Modern supplements sell it mainly for testosterone and libido, often stacked with a second herb, Fadogia agrestis.
What the Trials Show
The findings below are ranked by how much evidence stands behind each, and the order holds for almost any reader.
Two findings sit at the top. The pooled testosterone result draws on five randomized trials, and the stress-hormone result comes from a placebo-controlled trial that measured cortisol directly. Both concentrate in the men with the most room to move: those who were older or whose testosterone was low to start with. Below them sit the libido, erectile-function, and strength signals, each resting on one or two small trials. At the bottom is Fadogia agrestis, the herb tongkat ali is usually stacked with, which has no human trials at all.
Two limits run through the whole set:
- The evidence leans on one preparation. Several of the single trials used one branded water extract, Physta, and two of them were funded by its maker; the meta-analysis that pooled them declared no such funding. The results still stand, and the category rests on a narrower base than the count of studies suggests.
- The trials are short. Follow-up ran weeks, not years, so durability and longer-term effects are not yet mapped.
One of the findings is a comparison. Set against the whole shelf of marketed testosterone boosters, most of which do nothing measurable, tongkat ali is one of the few with any signal. That places it above most competitors and still short of proof. How strong the evidence is and how large the effect is are two different things.
Then there is the stack. Tongkat ali is very often sold with Fadogia agrestis, a West African shrub promoted on the same testosterone claim. Their evidence is not comparable: tongkat ali has small human trials; Fadogia agrestis has none, and the specifics of its animal signals are in the cautions below.
Take tongkat ali on its own. Fadogia agrestis has no human trial behind it and an animal testicular-toxicity signal, so pairing the two adds risk without adding studied benefit.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Progress Markers
Total testosterone rose in men across five trials (SMD 1.35), most in those low to start
Across the randomized trials pooled together, tongkat ali raised testosterone in men, and the increase was clearest in older men and men whose testosterone was low to start with.
A meta-analysis of five randomized trials found tongkat ali raised serum total testosterone in men (standardized mean difference 1.35, 95% CI 0.57 to 2.14), with the effect confirmed in the hypogonadal subgroup. A 12-week placebo-controlled trial in 105 men aged 50 to 70 with testosterone below 300 ng/dL saw total testosterone rise on 200 mg a day of a standardized extract. Measured in: Men, pooled from randomized trials of healthy and hypogonadal volunteers; the largest single RCT enrolled 105 men aged 50 to 70 with low testosterone.. The trials are small and heterogeneous, several are built around a single branded water extract (Physta) and some were funded by its manufacturer, and the effect is larger in hypogonadal or older men than in men already in the normal range. Follow-up was 4 to 12 weeks.
Who this may not transfer to:The pooled testosterone trials were in men, and the outcome is male serum testosterone in the context of hypogonadism and aging, so the finding does not transfer to women.
The studies · 3
Leisegang et al. 2022, Medicina · Medicina (Kaunas) 2022;58(8):1047
Chinnappan et al. 2021, Food Nutr Res · Food Nutr Res 2021;65:5647
Tambi et al. 2012, Andrologia · Andrologia 2012;44 Suppl 1:226-30
Counts once: this finding and 2 others here come from the same source, so they are one body of evidence, not separate confirmations.
Across 52 studies of testosterone boosters, most did nothing; tongkat was one of the few with a signal
When researchers reviewed the whole shelf of testosterone-booster supplements, most did nothing measurable; tongkat ali was one of the few with any measurable signal.
A systematic review of 52 studies covering 27 marketed testosterone-boosting ingredients found that most did not measurably raise total testosterone. Eurycoma longifolia was among the few judged possibly effective, for men with late-onset hypogonadism and for healthy men. Measured in: Systematic review across male athletes, men with late-onset hypogonadism, infertile men and healthy men.. The review's own verdict for tongkat ali is possibly effective, not established, and rests on the same small trial base graded elsewhere on this page; the label distinguishes it from ineffective ingredients rather than proving a large effect.
Who this may not transfer to:The review's outcome was serum total testosterone in male populations, so it does not speak to effects in women.
The study · 1
Morgado et al. 2024, Int J Impot Res · Int J Impot Res 2024;36(4):348-364
Anxiety And Stress
Cortisol fell about 16% and testosterone rose about 37% over four weeks under stress
In stressed adults, four weeks of a standardized extract lowered the stress hormone cortisol, raised testosterone slightly, and improved several mood scores.
In 63 moderately stressed adults, four weeks of a standardized hot-water root extract lowered salivary cortisol by about 16% and raised testosterone status by about 37%, with reductions in tension (-11%), anger (-12%) and confusion (-15%) on a standardized mood scale. Measured in: 63 adults (32 men and 31 women) screened for moderate stress, placebo-controlled.. A single small 4-week trial in a self-selected moderately stressed group, using one standardized extract; the mood measures are self-reported scales and the result has not been replicated at this size.
Who this may not transfer to:The trial enrolled both men (32) and women (31) and reported the pooled effect across the group.
The study · 1
Talbott et al. 2013, J Int Soc Sports Nutr · J Int Soc Sports Nutr 2013;10(1):28
Sexual Function
Erectile-function scores improved over 6 months in aging men on 200 mg a day
Over six months, a daily standardized dose improved erectile-function scores in aging men, most so when it was paired with regular exercise.
In a 6-month randomized trial in 45 men (mean age 47) with androgen deficiency of aging, 200 mg a day of a standardized extract improved erectile-function scores and total testosterone, with the largest improvement in the group that combined the extract with concurrent exercise training. Measured in: 45 men, mean age about 47, with androgen deficiency of aging (ADAM), randomized across four arms.. The trial had no arm testing the extract alone against training alone, so its independent contribution cannot be cleanly separated from the exercise, and the sample was small.
Who this may not transfer to:Erectile function is a male-specific outcome measured only in men, so it does not transfer to women.
The study · 1
Leitao et al. 2021, Maturitas · Maturitas 2021;145:78-85
Energy And Fatigue
Fatigue and aging-male symptoms fell over 12 weeks on 200 mg a day
Older men with low testosterone reported less fatigue and fewer aging-related symptoms on a standardized dose over 12 weeks.
In the 12-week placebo-controlled trial in 105 aging men with low testosterone, 200 mg a day of a standardized extract reduced Fatigue Severity Scale and Aging Male Symptoms scores compared with placebo, with the reduction appearing within two weeks. Measured in: 105 men aged 50 to 70 with testosterone below 300 ng/dL, placebo-controlled.. A single manufacturer-funded trial using symptom questionnaires; the outcomes are self-reported scales and the result has not been independently replicated at this size.
Who this may not transfer to:Measured only in aging men with low testosterone; the fatigue effect has not been tested in women or in men with normal levels.
The study · 1
Chinnappan et al. 2021, Food Nutr Res · Food Nutr Res 2021;65:5647
Counts once: this finding and 2 others here come from the same source, so they are one body of evidence, not separate confirmations.
Muscle And Strength
Handgrip strength rose in active seniors on 400 mg a day for five weeks
A couple of small studies found modest gains in muscle strength in older adults taking a standardized extract, though this was a secondary result and not the main question.
Muscle strength rose as a secondary endpoint in the 12-week placebo-controlled trial of a standardized extract in aging men, and an uncontrolled pilot in 25 physically active seniors (13 men, 12 women) taking 400 mg a day for five weeks reported increased handgrip force alongside higher testosterone. Measured in: Aging men in a 12-week RCT (strength as a secondary endpoint) and 25 physically active seniors aged 57 to 72 in an uncontrolled 5-week pilot.. Strength was a secondary endpoint in one trial and the supporting pilot had no control group, so the ergogenic signal is thin and not yet tested as a primary outcome.
Who this may not transfer to:The pilot included both men and women aged 57 to 72 and reported strength gains in both, while the RCT strength endpoint was in men.
The studies · 2
Chinnappan et al. 2021, Food Nutr Res · Food Nutr Res 2021;65:5647
Henkel et al. 2014, Phytother Res · Phytother Res 2014;28(4):544-50
Counts once: this finding and 2 others here come from the same source, so they are one body of evidence, not separate confirmations.
How it works
Fadogia agrestis raised testosterone in rats at 18 to 100 mg/kg, never tested in people
The testosterone reputation of Fadogia agrestis comes entirely from rat studies, where it raised testosterone and mating behavior. It has never been tested in people.
In male rats, an aqueous stem extract of Fadogia agrestis at 18, 50 and 100 mg/kg raised serum testosterone in a dose-related way and increased mounting and intromission frequency over five days. No human trial of Fadogia agrestis has been published. Measured in: Male albino rats; no human studies exist.. This is a rodent finding only, at doses and by a route that do not translate to human use, and the same research line reported testicular harm at sustained higher doses.
Who this may not transfer to:Measured only in male rats; no human trial of Fadogia agrestis has been done, so the finding does not transfer to people.
The study · 1
Yakubu et al. 2005, Asian J Androl · Asian J Androl 2005;7(4):399-404
How It Works
Anatomy of the Practice
1In the stress and hormone system
Tongkat ali acts on the hormonal stress response. In moderately stressed adults, four weeks of a standardized extract lowered cortisol and raised testosterone at the same time. The ratio between those two hormones is a rough marker of whether the body is building tissue or breaking it down, and this part of the mechanism has the most direct human measurement behind it.
2On free testosterone
Some testosterone in the blood is bound to a carrier protein, SHBG, and is not available to tissues. Part of the herb's action is a rise in the unbound fraction; one trial in older adults saw free testosterone rise as that carrier protein fell. The shift is modest and measured in small groups.
3Who it moves most
Any hormonal shift is larger in men who started with low testosterone and smaller in men already in the normal range, where there is less to change. The effect works through the body's own production, so it depends on a system that can still respond.
The quassinoids in the root, eurycomanone chief among them, raise testosterone in laboratory and animal studies by acting on the signaling that drives testosterone production in the testes and by influencing the enzyme that converts testosterone into estrogen. That mechanism fits the human trials, which measured a rise in testosterone and a drop in cortisol. It depends on a hormone system that can still respond, which is why the effect is smaller in a man whose levels are already normal.
Tongkat ali increases the body's own testosterone output. Testosterone therapy replaces testosterone from outside and raises it into a range a clinician targets, with monitoring for fertility and blood thickness. Reading a supplement result as a milder version of that therapy is the most common way this evidence gets stretched. The dose the trials used, 100 to 400 mg a day of a standardized water extract, is also specific, and it differs from the raw-root capsules and high-dose blends that fill the market.
Choosing and Using It
Ways to Do It
The levers that raise testosterone and steady stress hormones are mostly free, and they are the first thing to try for any man. A standardized extract is a low-cost addition on top of those basics, most useful for older men or men with confirmed low testosterone, and best decided with a clinician who can check your levels.
Losing excess weight, sleeping enough, treating sleep apnea, resistance training, and drinking less alcohol each raise testosterone or lower the stress hormones that suppress it. Together they move it more than any capsule, and they have the strongest evidence behind them. A supplement added on top of neglected basics does the smaller share of the work.
The human trials used a standardized water extract of the root, most often 200 mg a day and ranging from about 100 to 400 mg, taken for four to twelve weeks. Raw-root powder and undefined blends are not the material the research measured. If your aim is fatigue, stress, or low testosterone confirmed on a blood test, this is the studied range, and it is a decision to make with a clinician who can check your levels before and after.
Market surveys have found mercury above safe limits in tongkat ali products, and standardization varies widely between brands. A product carrying an independent testing mark, such as NSF or Informed Choice, or a published heavy-metal certificate of analysis, is the simplest way to know the capsule holds a defined extract and not contamination.
Because the trials ran weeks and not years, a defined trial of your own works better than an open-ended habit: a set dose for eight to twelve weeks, tracking one symptom or lab value, then a break to see what holds without it. That keeps the cost and the exposure bounded while the long-term picture is still thin.
The popular pairing with Fadogia agrestis adds an ingredient with no human trials and an animal testicular-toxicity signal at higher doses. Taking tongkat ali on its own keeps you on the ingredient studied in people. The specifics of the Fadogia signal are in the cautions below.
Go Deeper
- Testosterone therapy: the difference between low testosterone that needs treatment and the normal decline of aging, what medical treatment changes and what it leaves untouched, and the self-directed levers that come first.
- Ashwagandha: the other adaptogenic herb marketed for stress and testosterone, with its own small trial base, useful as a comparison for how these claims are graded.
The Chinese Medicine View
Tongkat ali grows in Southeast Asia and belongs to the traditional medicine of Malaysia and Indonesia, not to the classical Chinese pharmacopoeia. No channel, temperature, or flavor is assigned to it in the Chinese texts, and reading one back into it would be an invention. What the Chinese tradition offers is a category its use resembles: the warming tonics aimed at what the tradition calls Kidney Yang, the faculty it links to drive, warmth, stamina, and reproductive vitality. That framing is laid over the herb as interpretation, held apart from the trial data above.
Read through that lens, a bitter warming root taken to restore energy and male vigor sits close to the Yang-tonifying herbs the tradition uses for someone who is cold, depleted, tired, and low in drive. The resemblance is suggestive given where the modern trials point, toward testosterone, fatigue, and stress. It rests on a shared subject; the tradition had no concept of the hormone the trials measure.
Where the tradition earns its place here is the caution it attaches to warming tonics. Chinese medicine does not treat a Yang tonic as good for everyone. It is understood to suit the cold and depleted person and to burden the person who already runs hot or dry. The tradition reads signs like night sweats, a red flushed face, restlessness, or heat in the palms as Yin deficiency, and warming the system further is thought to add to that heat. That sits close to the modern reading, where the measured benefit falls mainly to the men who were depleted to begin with and thins out in those who were not. The framing is a way of thinking, not a claim about the molecule.
Cautions For This Practice
Extra restraintEverything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
Mercury above the limit in 36% of tongkat ali products tested
In a survey of 100 tongkat ali herbal preparations from the Malaysian market, 36% contained mercury from 0.52 to 5.30 ppm, above the permitted limit for traditional medicines, with contamination varying batch to batch. This is a market-quality problem rather than a property of the herb, measured in Malaysian products; it argues for standardized, independently tested extracts rather than unverified powders.Ang et al. 2004, Int J Toxicol
Fadogia agrestis harmed rat testicular function over 28 days of dosing
In male rats given an aqueous Fadogia agrestis stem extract daily for 28 days at 18, 50 and 100 mg/kg, testicular function indices shifted in a direction the authors described as adverse to testicular function, with recovery mainly at the lowest dose. Related work reported liver and kidney changes. This is an animal toxicity signal at sustained higher doses; human safety has not been studied, so the size and threshold of any risk in people is unknown rather than reassuringly absent.Yakubu et al. 2008, J EthnopharmacolYakubu et al. 2009, Hum Exp Toxicol
Fadogia agrestis, the common stack partner, has an animal testicular-toxicity signal and no human data
Fadogia agrestis is sold alongside tongkat ali on the same testosterone claim, and it has never been tested in a single human trial. Its reputation comes from rat studies, where a stem extract raised testosterone and mating behavior at low doses, and where daily dosing at higher amounts over four weeks altered the testicular tissue in a way the researchers described as adverse, with recovery mainly at the lowest dose. Related animal work also reported liver and kidney changes. Until there is human safety data, the cautious position is to keep to tongkat ali on its own.
Heavy-metal contamination in some products
Market surveys of tongkat ali preparations have found mercury above the permitted limit in a sizeable share of products, with levels varying batch to batch and by source. This is a product-quality problem, not a property of the herb, and it is the main reason to buy a standardized extract that carries independent heavy-metal testing.
Hormone-sensitive conditions and fertility treatment
Tongkat ali can shift testosterone and related hormones, so anyone with a hormone-sensitive condition, being treated for one, or undergoing fertility treatment should raise it with their clinician before starting. The direction and size of any hormonal effect in these situations has not been mapped in trials.
Existing medication and medical conditions
The human trials were short and run mostly in otherwise healthy men, so effects alongside long-term medication, or in people with significant heart, liver, or kidney conditions, are not well characterized. If you take regular medication or manage a chronic condition, tell the clinician who oversees it before adding tongkat ali, and keep to the doses and standardized extracts used in the research.
It is not a replacement for testosterone therapy
Confirmed low testosterone is a medical diagnosis made on morning blood tests, and its treatment is a decision for a clinician. Tongkat ali produces a modest shift within your own production and does not substitute for that assessment. Using it to self-treat symptoms that could reflect hypogonadism can delay a diagnosis that matters, so persistent symptoms should be investigated properly.
Pregnancy, breastfeeding, and use by women
Most of the human research is in men. Tongkat ali has not been studied for safety in pregnancy or breastfeeding, so the sensible course there is to avoid it. The small trials that included women were short and few, so its effects in women are not well established.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
Does tongkat ali actually raise testosterone?
Modestly, and mostly in men who were low to begin with. Pooled across the randomized trials, tongkat ali raised total testosterone, with the clearest effect in older or hypogonadal men and little to show in younger men already in the normal range. The trials are small and several are built around one branded extract, so the effect is modest and narrower than the marketing, and it works within your own production.
Is tongkat ali the same as testosterone therapy?
No. Testosterone therapy is a prescribed medicine that replaces testosterone and raises it into a target range, with effects on fertility and blood thickness that need medical monitoring. Tongkat ali is a root extract that produces a modest shift within your body's own production, measurable mainly in men who started low. If you have symptoms of low testosterone, the first step is a morning blood test and a clinician's read.
Should I stack tongkat ali with Fadogia agrestis?
The two are sold together, but their evidence is not comparable. Tongkat ali has small human trials; Fadogia agrestis has none, and the animal studies behind its reputation also found testicular harm when higher doses were given over several weeks. Taking tongkat ali on its own keeps you on the ingredient studied in people while human safety data for Fadogia does not exist.
What dose of tongkat ali did the studies use?
The human trials used a standardized water extract of the root, most often 200 mg a day, across a range of about 100 to 400 mg, taken for four to twelve weeks. That standardized extract differs from raw-root powder and from undefined blends, so the label matters. Because product quality and heavy-metal contamination vary, a third-party-tested extract at the studied dose is the version closest to what the research measured.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 13 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 9, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.