Tongkat Ali is an herbal supplement with alleged aphrodisiac and testosterone-boosting effects. Men use it to enhance sexual health and performance, and some evidence backs them up. Early research is also exploring the impact of this plant on osteoporosis, diabetes, and anxiety. Read more below to learn about the science behind Tongkat Ali, including dosage, reviews, and side effects.
What is Tongkat Ali?
Eurycoma longifolia, commonly known as Tongkat Ali, long jack, or Malaysian ginseng, is a plant found in the Malaysian rainforest .
Men use it for erectile function and for enhancing libido, sexual performance, fertility, testosterone, earned it the nickname “Malaysia’s home-grown Viagra” .
Scientists are also exploring whether this plant affects:
- Bone formation 
- Muscle strength and athletic performance 
- Physical and mental energy levels and quality of life [5, 6]
- Anxiety and stress 
- Bacteria and yeast 
- Ulcers 
- Antioxidant defense 
- Blood sugar 
However, clinical trials are sparse. Only a handful of Tongkat Ali’s uses are supported by solid evidence.
Additionally, Tongkat Ali supplements have not been approved by the FDA for medical use. Supplements generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
Another serious concern is that some Tongkat Ali supplements from Malaysia have been found to contain toxic metals, drugs, or unknown plant compounds. If you decide to supplement, take careful measures to get a high-quality, pure herbal extract.
The stem and root extracts of Eurycoma longifolia contain:
- Quassinoids (e.g., eurycomaoside, eurycomanone, pasakbumin-B): The antiparasitic, and antiulcer effects of these compounds are an area of research [11, 8].
- Alkaloids, the antibacterial properties of which are being investigated [12, 10, 13].
Mechanism of Action
The mechanism of action of Tongat Ali in humans is unknown. Scientists believe this plant might increase testosterone levels by stimulating the production of testosterone from pregnenolone and 17-OH-pregnenolone. Others hypothesize it blocks aromatase, the enzyme that converts testosterone to estrogen. These mechanisms remain unproven [14, 4].
Potential Health Benefits of Tongkat Ali
Possibly Effective for:
1) Infertility in Men
Some clinical evidence suggests that Tongkat Ali may the quality of sperm in infertile men.
In one 12-week study (DB-RCT) of 109 men (ages 30 to 55), Tongkat Ali increased sperm motility and semen volume compared to placebo .
In another 9-month study of 75 men with infertility, Tongkat Ali supplements improved semen volume, sperm concentration, sperm motility, and sperm quality, thereby improving infertility .
Scientists think that Tongkat Ali might work by reversing the inhibitory effects of estrogen on testosterone production, based on animal studies. This mechanism has not been confirmed in humans [15, 16, 17].
2) Sexual Desire
According to some trials, Tongkat Ali may increase sexual desire in healthy men.
In a 12-week study (DB-RCT) of 109 men, Tongkat Ali increased libido and improved erectile function compared to placebo .
In another 12-week study (DB-RCT) of 26 men, a specific freeze-dried water extract of Tongkat Ali (Physta) improved sexual performance and increased the hardness and duration of erections .
Tongkat Ali also enhanced libido, sexual arousal, and performance in healthy, impotent, castrated, and old male rats, and middle-aged mice [19, 20, 21, 22, 23, 24].
Possibly Ineffective for:
Some clinical data suggests that Tongat Ali doesn’t improve physical performance in athletes.
In one trial of recreational male athletes, Tongat Ali (150 mg daily) 7 days before and one hour prior to endurance running did not improve performance. In another trial of healthy men, a specific brand of Tongat Ali extract (Physta) 300 mg daily for 12 weeks did not improve physical fitness, compared to placebo [25, 5, 26].
Insufficient Evidence for:
The following purported benefits are only supported by limited, low-quality clinical studies.
There is insufficient evidence to support the use of Tongkat Ali for any of the below listed uses.
Remember to speak with a doctor before taking Tongkat Ali supplements. Tongkat Ali should never be used as a replacement for approved medical therapies.
There is insufficient evidence to suggest that Tongkat Ali increases testosterone levels, though early studies show some promise.
A 5-week pilot study of 25 seniors found that Tongkat Ali increased testosterone levels and muscle strength in both men and women. Tongkat Ali supplementation also increased testosterone levels in a 4-week study of 76 men with hypogonadism (an impaired function of the testes) [27, 6].
Testosterone blood levels are used to monitor men with low testosterone levels. Urinary testosterone is mainly used in forensics to evaluate testosterone doping .
In a 15-week study (DB-RCT) of 13 recreational athletes, Tongkat Ali did not increase testosterone levels in the urine. Based on these findings, the authors concluded that supplementation should not breach the International Olympic Committee doping policies .
There is insufficient evidence to rate the effectiveness of Tongkat Ali for improving muscle strength.
Tongkat Ali supplements increased muscle strength in both men and women in a 5-week pilot study of 25 seniors .
Similarly, in a 5-week pilot study of 14 healthy men, Tongkat Ali increased muscle strength and size and improved athletic performance .
Large-scale studies are needed.
Stress and Anxiety
Insufficient evidence exists to determine the effects of Tongkat Ali on stress and anxiety.
A 4-week study on 63 moderately stressed people showed that Tongkat Ali root extract reduced stress hormone (cortisol) levels, tension, anger, and confusion .
Tongkat Ali also reduced the frequency of fighting episodes and increased exploratory behavior in mice, which points to less anxiety in animals. We can’t extrapolate these findings to humans and proper clinical trials are lacking .
Immune System Response
There is insufficient evidence about the effects of Tongkat Ali on the immune system.
In a 4-week study (DB-RCT) of 83 subjects, Tongkat Ali supplements increased T cells, CD4+ T cells, and naïve T cell numbers, which enhanced overall immune function .
Insufficient evidence exists to determine if Tongkat Ali affects weight loss. Proper, large-scale clinical trials are needed.
In one 12-week study of 109 healthy men, Tongkat Ali reduced fat mass, waist circumference, and hip size compared to placebo. However, weight loss was not the primary focus of this study .
In another (pilot) study of 14 healthy, Tongkat Ali supplements increased muscle strength and size while decreasing body fat after 5 weeks. No conclusions can be drawn from this study, since it lacked a placebo group and included such a small sample. No other studies have replicated its findings .
Some scientists are also investigating whether Tongkat Ali affects body weight and belly fat in mice, but research is still in the early stages .
Lacking Evidence (Animal Research)
No clinical evidence supports the use of Tongkat Ali for any of the conditions listed in this section.
Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
In cell culture, researchers are exploring whether Tongkat Ali activates the production of bone-building proteins (such as BMP-2, RUNX-2, and OCN) that increase bone formation [33, 34].
One research group suggested that Tongkat Ali prevents calcium loss in the bones of castrated male rats with osteoporosis. However, in another study, Tongkat Ali did not restore testosterone levels and bone volume in the castrated rats with osteoporosis. Far more studies are needed [35, 36, 37].
Researchers are looking at how Tongkat Ali might affect the following bacteria and parasites in the lab:
- Salmonella, E. coli, staph, and typhoid-causing bacteria) .
- Blastocystis sp, a parasite that causes intestinal problems .
- Toxoplasma gondii, a parasite causing toxoplasmosis .
They suspect its quassinoids may have microbe-fighting properties [11, 41, 42, 43].
However, the effects of Tongkat Ali on infections in humans are unknown.
Other Areas of Research
Other areas of Tongkat Ali cellular and animal research include its potential effects on:
- Blood sugar control 
- Blood pressure 
- Antioxidant (free radical scavenging) defense 
- Inflammation 
- Ulcers 
- Alcohol-induced stomach injuries 
These effects remain unexplored in humans.
Lastly, Tongkat Ali is traditionally said to reduce fever, but there are no clinical or animal studies to support this .
Supplementing with Tongkat Ali
Safety & Toxin Contamination Concerns
Oral Tongkat Ali supplements are possibly safe when used at the appropriate dosage for up to 9 months.
However, you should be extremely cautious when purchasing Tongkat Ali supplements.
Some supplements from Malaysia have been found to contain toxic metals like mercury, cadmium, and lead.
Some were also adulterated with sildenafil (Viagra). Others don’t contain Tongkat Ali at all but loosely-related species. Adulteration with certain toxic chemicals can be deadly .
Be sure to purchase supplements only from a trusted manufacturers and do not hesitate to demand a quality certificate.
Studies suggest Tongkat Ali may cause :
Tongkat Ali herbal coffee was associated with high blood pressure in pregnant women and fetal discomfort .
Pregnant and breastfeeding women should avoid Tongkat Ali due to a lack of safety data.
Supplement-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.
Tongkat Ali may reduce the absorption of beta blockers (such as propranolol) .
Tongkat Ali inhibits the metabolic activities of CYP1A2, CYP2A6, and CYP2C19 enzymes. These enzymes are part of the CYP540 family, which are responsible for breaking down or activating drugs. Inhibition of these enzymes may cause interactions with specific drugs (e.g., some antidepressants, beta-blockers, statins, warfarin, and antiepileptics) [52, 53].
Forms of Supplementation
Tongkat Ali is an herbal supplement available in the form of tablets, water-soluble powder, and coffee [49, 50].
Most clinical trials used 200mg to 400mg of a Malaysian Tongkat Ali water extract daily [29, 6, 27].
The opinions expressed in this section are solely those of the users who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.
Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or another qualified healthcare provider because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
Some users describe Tongkat Ali as unsafe and report an enlarged prostate, increase in fat gain, anger, and bad night sweats after taking the herb:
“It’s great if you get the real stuff. But many sources on the web just sell tribulus and put a Tongkat Ali label on the bottle.”
“NOT SAFE!!! It ENLARGED MY PROSTATE for THE REST OF MY LIFE at my 34 YEARS OLD!!!” Still have trouble peeing and I’m terrified of harming my kidneys. Don’t take this supplement.”
“I have more fat on my chest, back, and stomach.”
“This herb has a strong effect when an active dose is taken. I got more sexual thoughts and improved erections. Unfortunately, I also got more angry and aggressive from this herb. It made my testicles swell, with less “shrinkage” at flaccid state, thicker semen, testicular aching, bad night sweats, and increased body hair.”
Some users report a boost in libido, energy, and sexual activity, as well as a drop in blood pressure:
“After week 3 I felt a real boost and had a strong increase in my libido and my sexual activity.”
“I felt more energized, my libido improved and my blood pressure dropped.”
“Successfully works as an aphrodisiac.”
“ More energy, strength, and libido. I feel 25 years younger than my age!”
“I’m 56 now, and my libido declined since I was younger. Tongkat Ali made my sex drive back to when I was in my 30s, and my energy levels are higher. However, when I take it late at night I have trouble sleeping.”
“Proper use of the product is very effective.”
Other users report an increase in muscle strength and performance:
“At age 60, it gave me longer, stronger, and meatier erections and lots of them. I even get spontaneous erections during the day. My workouts are far more productive and I sleep like a baby.”
“The results in muscle strength and muscle growth are great.”
“The amount of weights that I began to lift in the gym was notable and my strength just seems to triple.”
Some people experienced reduced pain after taking Tongkat Ali:
“Suffer from arthritis and when on naproxen I still had irregular pains in various parts of the body (mainly hands). For over six weeks with Tongkat Ali, feel almost completely pain-free.”