Tongkat Ali has been called “Malaysian ginseng” for decades, though it shares no botanical relationship with actual ginseng. The plant has become one of the more popular testosterone-boosting supplements in recent years, particularly among men concerned about age-related hormone decline.

I should be upfront: the research on Tongkat Ali is genuinely interesting but still limited. Most studies involve small sample sizes, and several come from Malaysian research groups who have obvious incentives to promote their national product. That said, some findings are intriguing enough to warrant a closer look.

What is Tongkat Ali?

Tongkat Ali (scientific name Eurycoma longifolia) is a tall, slender tree that grows in sandy soils across Southeast Asia, reaching heights of 10 to 15 metres. It belongs to the Simaroubaceae family and grows wild in Malaysia, Indonesia, Thailand, and Myanmar.

Traditional healers in these regions have used the roots, stems, and bark for centuries to treat fever, pain, dysentery, fatigue, and sexual complaints. The bitter taste of the root extract is something people frequently mention, though modern capsule forms avoid this problem entirely.

The plant contains several active compounds that researchers believe are responsible for its effects:

Quassinoids (particularly eurycomanone) - thought to be the main active components
Alkaloids - nitrogen-containing compounds common in medicinal plants
Triterpenes - a class of compounds also found in many adaptogens

Malaysian researchers have studied Tongkat Ali more extensively than scientists elsewhere, which makes sense given its cultural importance there. The extract is standardised in various ways, with “200:1” and “100:1” concentrations being common in commercial products.

What does the research actually show?

1. Erectile function

Erectile dysfunction affects a surprising number of men, with prevalence estimates ranging from 1-10% in men under 40 to 40-50% in men over 40. By age 70, organic causes (rather than psychological ones) account for most cases [1].

Here’s where things get complicated. A meta-analysis looking at two randomised controlled trials with 139 total participants found that Tongkat Ali supplementation did not significantly improve erectile function scores when compared to placebo [1].

However, subgroup analysis told a different story. Men who started with lower baseline erectile function scores (suggesting more severe dysfunction) saw meaningful improvements of around 5.2 points on the IIEF-5 scale. Men with mild dysfunction saw no benefit.

What to make of this? The subgroup finding is interesting, but subgroup analyses are notoriously unreliable. The sample sizes were small, and the trials came from research groups with potential bias. I wouldn’t bet the farm on Tongkat Ali for erectile dysfunction, but I also wouldn’t dismiss it entirely for men with more pronounced symptoms.

2. Testosterone levels

Testosterone declines naturally with age in men. This isn’t controversial. What’s more debated is whether modest declines warrant treatment and whether supplements offer meaningful help.

A randomised, double-blind, placebo-controlled study looked at men aged 50-70 with testosterone levels below 300 ng/dL (the threshold often used to define low testosterone) [2]. After 12 weeks of Tongkat Ali supplementation (200mg daily of standardised extract), the supplement group showed:

Higher total testosterone levels
Better quality of life scores
Reduced fatigue symptoms
Fewer symptoms associated with male ageing

This is probably the cleanest study on Tongkat Ali and testosterone. The improvements were statistically significant, though the sample size was still modest. Whether the testosterone increase would be clinically meaningful for symptoms depends on individual circumstances.

For younger men with normal testosterone levels, I’m sceptical there’s much benefit. The body generally maintains hormone levels within a set range, and supplementation tends to work better when there’s an actual deficiency to correct.

3. Male infertility

Male fertility problems contribute to roughly 40-50% of infertility cases, often involving issues with sperm count, motility, or morphology [3]. The condition sometimes gets overlooked since fertility discussions often focus on women.

A three-month study gave 75 men with unexplained infertility (no identified structural or hormonal cause) 200mg of standardised Tongkat Ali extract daily [3]. The results showed improvements in:

Semen volume
Sperm concentration
Sperm motility (how well they swim)
Sperm morphology (normal vs abnormal shapes)
Percentage of normal sperm overall

Did this translate to more pregnancies? The study didn’t follow up long enough to answer that question definitively. But the sperm parameter improvements were substantial enough to suggest potential clinical relevance.

This is one of the more promising applications for Tongkat Ali, though I’d want to see replication studies before recommending it as a primary treatment. It might be reasonable to try as part of a broader approach to male infertility.

4. Immune function

The immune system is extraordinarily complex, making supplement claims about “boosting immunity” often meaningless. What does boosting immunity even mean? More white blood cells? Faster responses? Neither is inherently good if it leads to autoimmune reactions or excessive inflammation.

That caveat aside, one randomised controlled trial looked at 84 middle-aged adults (both men and women) with self-reported low immunity over four weeks [4]. The Tongkat Ali group showed:

Improved immune function scores on a standardised assessment
Increased total T cell counts
Higher CD4+ T cell numbers (the “helper” cells that coordinate immune responses)
More naïve T cells (these respond to new pathogens)

The immune changes are interesting from a mechanistic standpoint. Whether they translate to fewer infections or better health outcomes remains unknown. Four weeks is too short to measure real-world immune benefits.

5. Stress and cortisol

Tongkat Ali is classified as an adaptogen, a category of substances thought to help the body resist physical and mental stressors. The adaptogens category includes ginseng, ashwagandha, and Rhodiola rosea.

Some research has examined Tongkat Ali’s effects on cortisol, the primary stress hormone. Chronically elevated cortisol is associated with various health problems including weight gain, immune suppression, and mood disturbances.

A small study in stressed adults found that four weeks of Tongkat Ali supplementation reduced cortisol levels and improved mood parameters compared to placebo [5]. The stress-reducing effects may partly explain improvements seen in testosterone (since chronic stress suppresses testosterone production) and immune function.

The adaptogenic research on Tongkat Ali isn’t as robust as for some other herbs in this category, but the early findings are consistent with traditional uses.

Side effects

Based on available clinical trials, Tongkat Ali appears reasonably safe at standard doses. Studies using 200mg daily for up to 9 months or 400mg daily for 3 months have not reported serious adverse events [6].

Reported side effects include:

Insomnia
Restlessness
Anxiety or agitation
Increased body temperature

These make sense pharmacologically if Tongkat Ali genuinely raises testosterone and reduces cortisol. Both changes could theoretically increase alertness and energy, which becomes problematic if taken too close to bedtime.

I’d suggest starting with lower doses and taking it in the morning rather than evening if you’re concerned about sleep disruption.

Who should avoid Tongkat Ali? (6 contraindications)

1. Pregnant or breastfeeding women

No safety data exists for Tongkat Ali during pregnancy or lactation. Given the potential hormonal effects, avoidance is sensible until research proves otherwise. The same applies to children.

2. People with liver or kidney problems

The body processes Tongkat Ali through the liver and eliminates it via the kidneys. Without specific safety studies in people with impaired organ function, it’s impossible to know whether normal doses could accumulate to harmful levels.

3. Quality concerns and contamination

This one is less about the herb itself and more about the supplement industry. Testing has found some Tongkat Ali products contaminated with mercury, cadmium, lead, and other toxic metals [7]. Even more concerning, some products have been found to contain undeclared sildenafil (Viagra) as an adulterant [8].

If you’re going to try Tongkat Ali, choose products from reputable manufacturers who provide third-party testing certificates. Don’t buy the cheapest option from unknown brands.

4. Hormone-sensitive conditions

Because Tongkat Ali may raise testosterone levels, people with conditions that could worsen from higher androgens should avoid it. This includes:

Prostate cancer or benign prostatic hyperplasia
Male breast cancer
Heart disease (testosterone can affect cardiovascular risk)
Sleep apnoea (may worsen with testosterone)
Polycythaemia (high red blood cell counts)

Women with hormone-sensitive conditions (certain breast cancers, endometriosis, uterine fibroids) should also avoid Tongkat Ali due to potential hormonal effects.

5. Drug interactions with propranolol

Propranolol is a beta-blocker used for high blood pressure, heart arrhythmias, and anxiety. Research suggests Tongkat Ali may interfere with propranolol’s effectiveness [6]. If you take this medication, discuss with your doctor before using Tongkat Ali.

6. CYP enzyme interactions

Tongkat Ali inhibits several liver enzymes involved in drug metabolism: CYP1A2, CYP2A6, and CYP2C19 [9]. If you take medications processed by these enzymes, Tongkat Ali could cause drug levels to rise, potentially increasing side effects.

Medications affected include:

Amitriptyline (antidepressant)
Omeprazole, lansoprazole, pantoprazole (acid reflux medications)
Diazepam (anxiety medication)
Warfarin (blood thinner)
Theophylline (asthma medication)
Verapamil (heart medication)

This isn’t an exhaustive list. If you take prescription medications, check with a pharmacist about potential interactions before starting Tongkat Ali.

What’s a reasonable dose?

Most clinical trials have used 200-400mg daily of standardised extract. The “standardised” part matters because raw root powder contains far less of the active compounds. Products standardised for eurycomanone content (typically 1-2%) are more likely to match what was used in research.

For testosterone and fertility applications, 200mg daily seems sufficient based on available studies. Higher doses haven’t shown clearly superior results and may increase side effect risk.

The bottom line

Tongkat Ali has some genuine research behind it, which puts it ahead of many supplements marketed for similar purposes. The testosterone and fertility findings are the most compelling, though both need larger, longer studies for confirmation.

I’d consider Tongkat Ali potentially useful for:

Men over 50 with documented low testosterone levels
Men with unexplained fertility problems (as part of a comprehensive approach)
Possibly for stress management in otherwise healthy adults

I wouldn’t recommend it for:

Young men with normal testosterone hoping for a performance boost
Anyone expecting dramatic results
People unwilling to research product quality carefully

The supplement isn’t magic, but it may offer modest benefits for the right person. As with most things in health, individual responses vary considerably.

References

Kotirum S, Ismail SB, Chaiyakunapruk N. Efficacy of Tongkat Ali (Eurycoma longifolia) on erectile function improvement: systematic review and meta-analysis of randomized controlled trials. Complement Ther Med. 2015;23(5):693-698. https://pubmed.ncbi.nlm.nih.gov/26365449/
Henkel RR, Wang R, Bassett SH, et al. Tongkat Ali as a potential herbal supplement for physically active male and female seniors—a pilot study. Phytother Res. 2014;28(4):544-550. https://pubmed.ncbi.nlm.nih.gov/23754792/
Ismail SB, Wan Mohammad WMZ, George A, et al. Randomized Clinical Trial on the Use of PHYSTA Freeze-Dried Water Extract of Eurycoma longifolia for the Improvement of Quality of Life and Sexual Well-Being in Men. Evid Based Complement Alternat Med. 2012;2012:429268. https://pubmed.ncbi.nlm.nih.gov/23243445/
George A, Suzuki N, Abas AB, et al. Immunomodulation in Middle-Aged Humans via the Ingestion of Physta Standardized Root Water Extract of Eurycoma longifolia Jack-A Randomized, Double-Blind, Placebo-Controlled, Parallel Study. Phytother Res. 2016;30(4):627-635. https://pubmed.ncbi.nlm.nih.gov/26816234/
Talbott SM, Talbott JA, George A, Pugh M. Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects. J Int Soc Sports Nutr. 2013;10(1):28. https://pubmed.ncbi.nlm.nih.gov/23705671/
Mayo Clinic. Eurycoma longifolia. https://www.mayoclinic.org/drugs-supplements-eurycoma-longifolia/art-20363970
Low BS, Das PK, Chan KL. Standardized quassinoid-rich Eurycoma longifolia extract improved spermatogenesis and fertility in male rats via the hypothalamic-pituitary-gonadal axis. J Ethnopharmacol. 2013;145(3):706-714. https://pubmed.ncbi.nlm.nih.gov/23261483/
Baki A, Paek KY. Production of chemical compounds in Eurycoma longifolia (Tongkat Ali) by tissue culture. Adv Appl Microbiol. 2014;89:103-121. https://pubmed.ncbi.nlm.nih.gov/24731345/
Teh CH, Abdulghani M, Morita H, et al. Comparative X-ray and conformational analysis of a new crystal of 13α,21-dihydroeurycomanone with eurycomanone from Eurycoma longifolia and their anti-estrogenic activity using the uterotrophic assay. Planta Med. 2015;77(2):128-132. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC4512589/