What Is Tongkat Ali? Testosterone Benefits, Dosing, and the Science

Tongkat ali (Eurycoma longifolia), also known as longjack or Malaysian ginseng, is a plant native to Southeast Asia that has long been used in traditional medicine as a male tonic. It has become one of the best-known herbal testosterone supplements, driven by a small number of clinical studies. This article reviews what those studies found, what they cannot tell us, and the safety and quality problems worth knowing about.

This article is educational and is not medical advice. Supplements are not intended to diagnose, treat or prevent any condition. Talk to a doctor before starting any supplement, especially if you take medication or have symptoms such as persistent fatigue or low libido.

What Is Tongkat Ali?

Eurycoma longifolia is a tree found in the rainforests of Southeast Asia. The root is the traditionally used part. It contains a mix of compounds including quassinoids such as eurycomanone. Commercial products range from raw root powder to concentrated, water-extracted preparations, and these are not interchangeable: the human studies below used specific standardized extracts.

How Might Tongkat Ali Affect Testosterone?

Several mechanisms have been proposed, including effects on cortisol, on sex hormone-binding globulin (SHBG) and on testosterone production in the testes. Most of this mechanistic evidence comes from animal and laboratory studies, and it has not been firmly established in men. Think of these as hypotheses rather than established explanations. For background on why the difference between free and total testosterone matters, see our explainer.

The Key Randomized Trial: Stressed Adults

The most widely cited trial was published in 2013 in the Journal of the International Society of Sports Nutrition. Sixty-four moderately stressed adults (32 men and 32 women) were randomized to 200 mg a day of a branded water-extracted product (Physta) or a look-alike placebo for 4 weeks; 63 were analyzed. Compared with placebo, the tongkat ali group had lower scores for tension (-11%), anger (-12%) and confusion (-15%), 16% lower salivary cortisol, and 37% higher salivary testosterone.^[1]

Read this result carefully. The sample was a mix of men and women, the measurements were from saliva, the trial lasted only 4 weeks, and it was funded by Biotropics Malaysia, which makes the extract, and one author was an employee of a company that manufactures tongkat ali extract.^[1] The 37% figure therefore cannot be assumed to apply to men with low testosterone, or to other products.

Other Evidence

An uncontrolled study gave 200 mg a day of a standardized water-soluble extract for one month to 76 patients with late-onset hypogonadism. Their Aging Males' Symptoms scores and serum testosterone improved, and the proportion with testosterone in the normal range rose from 35.5% to 90.8%.^[6] With no placebo group, the result cannot be attributed to the extract. Late-onset hypogonadism is a medical diagnosis that should be evaluated by a doctor, not self-treated with a supplement.

A 2022 systematic review and meta-analysis found nine studies, of which five randomized trials were pooled. It reported a significant increase in total testosterone with E. longifolia (SMD 1.352, 95% CI 0.565 to 2.138), including in hypogonadal men, and called it a possible and promising option while stating that more research is needed before clinical use.^[2] The wide interval and small number of trials mean the true effect size is uncertain.

Doses Used in Studies and Product Quality

Both studies above used 200 mg a day of a water-extracted product, for 4 weeks to 1 month.^[1][6] That is what was studied; it is not a recommendation, and no optimal or safe long-term dose has been established. Extract type, strength and eurycomanone content vary widely between products, so results from one branded extract may not carry over to another.

Quality is a documented concern. Researchers who screened ten commercial products containing E. longifolia found that spectra for two products bought online closely matched sildenafil (a prescription erectile dysfunction drug), suggesting a sildenafil analogue had been added.^[3] In a separate survey of 100 tongkat ali hitam products sold in Malaysia, 26% contained 0.53 to 2.35 ppm of mercury, above the 0.5 ppm quality limit for traditional medicines there.^[4] Undeclared drugs and heavy metals are a safety risk, especially for men taking nitrate or blood pressure medication.

Side Effects and Safety

We did not find robust long-term human safety data. A 2025 case report described a 71-year-old man who developed new-onset atrial flutter after starting tongkat ali, with other causes ruled out; a single case cannot prove cause, but it is a reminder that herbal products can affect the heart.^[5]

Tongkat Ali in Context

Tongkat ali has some encouraging but limited and partly industry-funded evidence. It is not a substitute for the basics. If your sleep is poor, your stress is unmanaged, or you are not training consistently, no supplement will make up for it. For a head-to-head look, see ashwagandha vs tongkat ali. You may also want to read about shilajit, cistanche tubulosa, the fadogia agrestis safety and evidence review, and our broader guide to what the evidence says about testosterone supplements.

How Thrive Helps

Thrive helps you build and track the sleep, training, stress and nutrition habits that shape your hormonal baseline. Try Thrive free. Thrive is a wellness app, not a medical device, and does not diagnose or treat any condition.