Tongkat ali is a herbal supplement made from the root of a Southeast Asian plant called Eurycoma longifolia. It’s best known for its potential to support testosterone levels, reduce stress hormones, and improve body composition, and it has become one of the more popular natural supplements in the fitness and men’s health space. Most clinical trials use 100 to 400 mg per day of a standardized water extract, with effects typically appearing after four to twelve weeks.
Where It Comes From
The plant grows natively in Malaysia, Indonesia, Thailand, and Vietnam, where it goes by different local names: tongkat ali in Malaysia, pasak bumi in Indonesia, and tung saw in Thailand. It’s a slender tree, and virtually all the therapeutic interest centers on the root, which is dried and processed into powder or standardized extracts. The root contains a complex mix of bioactive compounds, with the most important group being quassinoids. Among these, one compound called eurycomanone appears to drive most of the plant’s health effects.
Commercial supplements typically come as a water-extracted root powder, sometimes standardized to contain a specific percentage of active peptides. The raw root itself is intensely bitter, which is why capsules and tablets dominate the market.
Effects on Testosterone
The headline claim for tongkat ali is that it raises testosterone, and there is real clinical evidence behind this. A systematic review and meta-analysis of human trials found a statistically significant increase in total testosterone levels among men taking tongkat ali supplements. The effect was particularly clear in men who started with low testosterone.
The size of the increase varies depending on the person and the dose. In one trial, men with low testosterone (averaging 51 years old) who took 200 mg per day saw their levels rise from an average of 163 to 240 ng/dL after one month. In another study, men taking 200 mg daily for up to six months saw levels climb from roughly 278 to 400 ng/dL. For men who already had healthy testosterone levels, the bumps were more modest. A group taking 400 mg per day for five weeks went from an average of 384 to 442 ng/dL.
What this means practically: tongkat ali is not going to produce the dramatic hormonal shifts you’d see with prescription testosterone therapy. But for men whose levels are on the low end, particularly due to aging or chronic stress, the research suggests a meaningful nudge upward. The effect also appears in women. A five-week trial of physically active seniors (ages 57 to 72) taking 400 mg daily found significant increases in both total and free testosterone, along with improved grip strength, in both men and women.
Stress and Cortisol Reduction
Tongkat ali’s effects aren’t limited to testosterone. A four-week trial gave 200 mg per day to 64 moderately stressed adults (split evenly between men and women) and measured changes in cortisol, the body’s primary stress hormone. The supplement group showed measurable improvements in mood and stress-related markers compared to placebo. This cortisol-lowering effect may partly explain the testosterone increase, since chronically elevated cortisol suppresses testosterone production. By bringing stress hormones down, tongkat ali may create conditions where the body produces more testosterone on its own.
Body Composition and Strength
Several trials have tested tongkat ali alongside exercise programs, and the combination consistently outperforms exercise alone. In one study, healthy men in their mid-twenties took 100 mg per day while following an intensive strength training program every other day for eight weeks. Compared to a placebo group doing the same workouts, the tongkat ali group gained more lean mass, lost more fat, and saw greater improvements in maximal strength and arm circumference.
Women see similar benefits. Middle-aged women (45 to 59 years old) who combined twice-weekly strength training with 100 mg per day for 12 weeks gained more fat-free mass than women doing the same training with a placebo. In a separate 12-week trial, men aged 30 to 55 taking 300 mg per day reported significant improvements in physical functioning on a quality-of-life survey.
These aren’t dramatic, supplement-ad-level results. They’re modest, consistent improvements that stack on top of an existing exercise routine.
Dosage and How Long It Takes to Work
Clinical trials have used doses ranging from 100 to 600 mg per day, but the most common and well-supported range is 100 to 400 mg per day of a standardized water extract. Recommendations based on the available human research typically call for 50 to 200 mg per day for general use.
Don’t expect overnight results. The timeline from clinical trials gives a rough guide:
- 2 to 4 weeks: Early changes in stress hormones and mood. Some testosterone increases visible in blood work, particularly at higher doses.
- 4 to 8 weeks: More noticeable improvements in energy, strength, and body composition when combined with exercise.
- 8 to 12 weeks: The timeframe where most trials measuring lean mass, fat loss, and physical functioning report their clearest results.
A two-month trial using 600 mg per day in healthy men aged 38 to 58 found no changes in blood markers, liver function, or kidney function, suggesting that even at higher doses, short-term use doesn’t appear to cause organ stress.
Safety and Side Effects
In animal toxicity studies, the lethal dose is extremely high (over 6 grams per kilogram of body weight), and a 13-week study found no adverse effects on body weight, blood chemistry, organ function, or tissue health. The calculated acceptable daily intake from that research was up to 1.2 grams per day for an adult, well above what any supplement provides.
Anecdotally, some users report sleep disruption, facial flushing, and restlessness, though these haven’t been confirmed in controlled studies. The more serious safety concern comes from the European Food Safety Authority (EFSA), which declined to approve tongkat ali extract as a novel food in the EU. Their review flagged potential DNA damage at high doses in lab and animal testing, particularly in tissues that first contact the substance (the stomach and upper intestine). This doesn’t mean tongkat ali causes cancer in humans at normal supplement doses, but it does mean the long-term safety picture is incomplete.
In the United States and Canada, tongkat ali is sold legally as a dietary supplement. It has been on the market internationally since at least 2009. Pregnant and lactating women were excluded from the proposed use in the EFSA application, and most researchers consider them a population that should avoid it.
Quality Problems in the Supplement Market
One of the biggest practical risks with tongkat ali isn’t the plant itself but the products claiming to contain it. An analysis of 100 tongkat ali products sold in Malaysia found that 26% contained mercury levels above the country’s safety limit of 0.5 parts per million, with some reaching as high as 2.35 ppm. Some products sold under the tongkat ali name have been banned in the US, Canada, and Singapore for containing undeclared prescription drugs or fake ingredients entirely.
If you’re choosing a supplement, look for products that use a standardized water extract, ideally with third-party testing for heavy metals and contaminants. Patented, clinically tested extracts are generally more reliable than generic root powder from unknown sources. The extract used in most published human trials is a water-based preparation standardized to its active peptide content, which is a useful benchmark when comparing products.