THE SHORT VERSION: The strongest research signals are for healthy testosterone within the normal range (clearest in older men) and for libido and sexual well-being in healthy men 30 to 55. Stress, energy, and strength results are early or mixed. Read them as promising, not proven. Consistency wins. Trials gave it daily for 4 to 12 weeks, and it works on top of training and sleep, not instead of them.
Tongkat ali has a big reputation and a smaller, real evidence base. Below is our scorecard: what the research supports, what's promising, and what's still unproven. Then who tongkat ali suits, how to use it well, and the straight answer on safety.
What Is Tongkat Ali?
Tongkat ali is the root of Eurycoma longifolia, a slender shrub native to Southeast Asia. It's one of the region's best-known traditional herbs and one of the most studied botanicals in men's health today.
The plant grows in the rainforests of Malaysia, Indonesia, Thailand, Vietnam, and neighboring countries.[1] For generations, traditional healers there used the root as a tonic for energy, strength, aging, and male vitality.[1] That history is why researchers took an interest. It isn't proof on its own, but it pointed science in a direction worth testing.
What's actually in the root? The headline compounds are quassinoids, a family of bitter plant compounds concentrated in the root. The most abundant is eurycomanone, a quassinoid that labs use as a marker to check that an extract contains what it should.[1][2] The root also carries proteins, polysaccharides, and glycosaponins, which are plant sugar compounds.[2]
Modern supplements don't use raw root shavings. The root is extracted in hot water and concentrated into a powder. Most of the human trials used one branded, standardized water extract, Physta®, made by a Malaysian company that also funded much of the research.[3][4]
What Does Tongkat Ali Do for Men? The Scorecard
Tongkat ali supports healthy testosterone levels within the normal range and supports male vitality and libido.* How strong the evidence is depends on the benefit, and on who's taking it.
The research base is real but small. The most recent meta-analysis, a study that pools results from other studies, could combine just five randomized controlled trials.[5] Most positive trials ran 4 to 12 weeks, enrolled a few dozen to about a hundred men, and were funded by the extract's manufacturer.[3][4] That doesn't make the results wrong. It means you should weigh each benefit on its own evidence. Here's how we grade them.
| Benefit | What the research shows | Our grade |
|---|---|---|
| Testosterone | Total testosterone was higher than placebo in older men whose levels started below 300 ng/dL. No significant change in healthy men 30 to 55. | Supported, population-dependent |
| Libido and sexual well-being | Sexual desire and sexual well-being scores improved versus placebo in healthy men 30 to 55 over 12 weeks. | Promising |
| Stress response and mood | Lower salivary cortisol and better tension, anger, and confusion scores in one 4-week trial. | Preliminary |
| Energy and fatigue | Fatigue scores improved in one trial of older men. Not consistently measured elsewhere. | Limited |
| Strength and body composition | Small grip-strength gains in older adults. No change in trained adults over 4 weeks. | Mixed |
| Traditional use | Generations of use as a root tonic in Southeast Asia. | History, not clinical proof |
The sections below walk through each row, with the studies behind it.
Testosterone: Supported, but It Depends on Who You Are
Tongkat ali supports healthy testosterone levels within the normal range.* The clearest results, though, come from older men whose levels started low, not from healthy younger men.
The largest placebo-controlled trial enrolled men aged 50 to 70 whose total testosterone started below 300 ng/dL. After 12 weeks on 200 mg a day of a standardized extract, average total testosterone moved from about 200 to 225 ng/dL, while the placebo group stayed flat.[3] Free testosterone, the unbound fraction your tissues can use directly, rose within groups but was not significantly different from placebo.[3]
A 2022 meta-analysis of five trials found tongkat ali was associated with higher total testosterone overall. The effect was more pronounced in men who started below 300 ng/dL and smaller in men with normal starting levels. The authors flagged high variability between studies and signs of publication bias, meaning positive studies may be overrepresented.[5]
Now the result that matters most if you're a healthy man in your 30s or 40s. In a 12-week trial of 109 healthy men aged 30 to 55 taking 300 mg a day, testosterone did not change significantly.[4]
So set your expectations accordingly. If your levels are already healthy, don't expect a dramatic new number on a lab report. Expect support for the range you already have. For the full study-by-study breakdown, read Tongkat Ali and Testosterone: What the Research Actually Shows.
Libido and Sexual Well-Being: The Signal That Fits Men 30 to 55
Tongkat ali supports male vitality and libido,* and this is where the trial closest to our audience delivered. Most men assume libido is a testosterone story. In this study, it wasn't.
The trial followed 109 healthy men aged 30 to 55 for 12 weeks on 300 mg a day of a standardized extract or a placebo. By week 12, the tongkat ali group reported about 14% higher sexual desire, and their overall sexual well-being scores improved more than placebo.[4] Scores for physical functioning, a quality-of-life measure covering everyday activity, also improved versus placebo.[4]
Here's the interesting part. Testosterone didn't change significantly in that same trial, so whatever drove the libido result, it doesn't appear to have run through a measurable testosterone shift.[4]
Keep it in proportion. A 2015 meta-analysis that pooled two randomized trials on sexual-function scores found no significant overall difference, with large variation between the studies.[6] Our read: a promising signal in healthy men, built on a small number of trials. That's why we grade it "promising" rather than "supported."
Stress Response and Mood: Early but Worth Watching
The stress research is genuinely interesting, and genuinely early. One small trial carries most of the weight.
Cortisol is your body's main stress hormone. It's useful in short bursts and wearing when it stays elevated. In a 4-week placebo-controlled trial, 63 moderately stressed adults took 200 mg a day of a standardized tongkat ali extract. Their salivary cortisol was lower than placebo, and their mood-questionnaire scores improved for tension (11%), anger (12%), and confusion (15%).[7]
Supporting evidence came from the large trial in older men, where cortisol also fell in the 200 mg group over 12 weeks.[3]
The caveats are real. The stress trial pooled men and women, measured hormones in saliva rather than blood, and ran just four weeks.[7] And a 2024 trial in exercise-trained adults found no change in cortisol or mood over four weeks.[8] Grade: preliminary. If stress management is your main goal, think of tongkat ali as a supporting piece next to sleep, training, and recovery, not the plan itself.
Energy and Fatigue: Limited Evidence So Far
Expect steady support, not a jolt. Energy is one of the top reasons men try tongkat ali, but the direct evidence is limited.
The clearest data point comes from the 12-week trial in older men. On a standard fatigue-severity questionnaire, scores in the 200 mg group dropped by about half, from roughly 58 to 29, while the placebo group didn't move.[3] That's a striking result. It's also one trial, in men aged 50 to 70 whose testosterone started below 300 ng/dL, so it may not translate to a 35-year-old with healthy levels.
Tongkat ali is not a stimulant. There's no caffeine in the root, and nothing about it should feel like a pre-workout. Men who notice an energy difference typically describe it as growing gradually with consistent daily use, which fits how the trials were run.
Prime Labs Tongkat Ali Plus is formulated to support energy, drive, and motivation.* We grade the research behind energy as "limited" because that's what it is. If you want training-day energy, that's a job for a pre-workout. Tongkat ali plays a longer game.
Strength and Body Composition: Mixed Results, Including a Null Trial
Tongkat ali won't put muscle on you by itself. The strength data are mixed, and one well-designed trial found nothing.
On the positive side, a small pilot study gave 400 mg a day to 25 physically active adults aged 57 to 72 for five weeks and reported gains in grip strength. It had no placebo group, so it can't separate the extract's effect from everything else.[9] The larger placebo-controlled trial in older men also found a small grip-strength gain, from about 60 to 63 kg over 12 weeks.[3]
Now the null result. In 2024, researchers gave 400 mg a day or a placebo to 33 exercise-trained adults for four weeks. They found no differences in lean mass, fat mass, grip strength, mood, or sleep.[8] On body fat specifically, the healthy-men trial showed only a non-significant trend among overweight participants.[4]
The U.S. Department of Defense's supplement-safety program sums it up fairly: a few studies suggest tongkat ali might support muscle strength in men, and it doesn't appear to help endurance performance.[10]
Our take: training is what develops strength. If that's your top goal, creatine has far deeper evidence. Start with our creatine guide, then use tongkat ali as support for workout performance and stamina* on top of a real program.
Who Is Tongkat Ali For?
Tongkat ali is for men 30 and up who already train, sleep, and eat with intent, and want to support drive, vitality, and healthy testosterone levels within the normal range.* It's a support piece for a solid routine, not a shortcut around one.
Men 30 to 55 focused on vitality: the healthy-men trial showed its clearest gains in libido and sexual well-being, not testosterone numbers.[4]
Men 50 and older: the strongest testosterone results came from older men whose levels had drifted lower.[3][5]
Men who train consistently: in a six-month trial in middle-aged men, the best results came from tongkat ali combined with a structured training program.[11]
Prime Labs Tongkat Ali Plus is not intended for women or anyone under 18. Talk to your doctor before taking it if you use blood thinners, SSRIs, MAOIs or other antidepressants, or hormone medications, or if you have a hormone-sensitive condition or a kidney or liver condition. And if you're worried about your hormone levels, skip the guesswork: see a doctor and get tested.
Is Tongkat Ali Safe?
In trials up to 12 weeks, tongkat ali was generally well tolerated, but long-term safety hasn't been established.
In the largest trial, the side effects reported were mostly mild stomach complaints such as constipation or indigestion, plus one case of itching, and none were judged related to the extract. There were no meaningful changes in liver enzymes, cholesterol, or blood pressure over 12 weeks.[3] In the healthy-men trial, safety measures were comparable to placebo.[4]
Two official sources add context. The NIH's LiverTox database lists tongkat ali as a possible rare cause of liver injury, based on limited case reports, and notes long-term safety is not well documented in humans.[12] In 2021, European food-safety regulators concluded that the safety of a standardized tongkat ali extract as a novel food had not been established, citing unresolved genotoxicity questions from lab and animal tests, not findings in people.[13] Product quality matters too: tongkat ali products sold elsewhere have been found contaminated with heavy metals or spiked with undeclared drugs.[10]
The practical takeaway: stay within the label directions, buy from a brand that discloses every dose and tests its product, and loop in your doctor if you take medication. For the full picture, read Is Tongkat Ali Safe? Side Effects, Tolerability & How to Take It Right.
How Do You Get the Most From Tongkat Ali?
Take it every day, stay in the studied range, and stack it on top of training and sleep. That's the formula the research actually tested.
Take tongkat ali daily. Every positive trial gave it every day for 4 to 12 weeks.[3][4][7] Skipped days are the most common reason a supplement "doesn't work."
Stay in the studied dose range. Trials used 100 to 400 mg a day of a standardized water extract, and typical use runs in the same range.[3][4][12] One two-capsule serving of the tongkat ali we make provides 400 mg of extract, so we suggest one serving a day.
Train with intent. In the six-month trial, tongkat ali paired with three training sessions a week gave the strongest results.[11] Pair it with creatine on training days for strength support.
Protect your sleep. Recovery is where training pays off. No supplement makes up for chronic short nights.
Give it 12 weeks, then reassess. That's the longest common timepoint in the trials. Results may vary. More on timing in How Long Does Tongkat Ali Take to Work, and Should You Cycle It?
Don't double up on testosterone-support formulas. Overlapping ingredients make it easy to exceed the studied range without realizing it.
Worth knowing: the trials used standardized water extracts, mostly Physta®, at 100 to 400 mg a day. Prime Labs Tongkat Ali Plus uses a 100:1 extract, which describes how much raw root was concentrated into the extract. A ratio isn't a standardized potency measure, and our formula wasn't the product tested in these studies. Our full dosing breakdown is in Tongkat Ali Dosage: How Much Per Day, and What "100:1" Means.
The Approach We Don't Recommend: Megadosing
More isn't better. Some bodybuilding products sell 1,000 mg or more a day, well past the range used in research.[12] No trial shows a bigger dose delivers a bigger result, and the liver-injury case LiverTox describes involved a bodybuilding product.[12] Stick to the label and never exceed 4 capsules in 24 hours.
