Ingredient Guide
Tongkat Ali: Benefits, Dosage, and What the Research Says
Supporting testosterone, stress resilience, and male vitality - here is what the clinical evidence actually shows
Written by Jessica Medson
Tongkat Ali (Eurycoma longifolia, also marketed as Longjack) is a root extract from a Southeast Asian tree used for centuries in traditional medicine to support male vitality. A 2022 systematic review and meta-analysis of five randomized controlled trials found a statistically significant increase in total serum testosterone in men supplementing with standardized extract (SMD = 1.35; 95% CI: 0.56 to 2.14; p = 0.001), with the largest effects seen in men with low baseline levels. Human research also suggests it may help maintain healthy cortisol levels within the normal range and support semen quality, though most studies are short-term and some evidence gaps remain.
What Is Tongkat Ali?
Tongkat Ali (Eurycoma longifolia Jack), also sold under the names Longjack and Malaysian ginseng, is a slender flowering tree native to the tropical rainforests of Southeast Asia - particularly Malaysia, Indonesia, and Thailand. Traditional healers throughout the region have prepared the plant's bitter root as a tea or decoction for centuries, primarily to support male energy, libido, and general vitality. The Malay name translates loosely to "Ali's walking stick," a longstanding reference to the root's reputation for supporting male vigor.
Modern supplement science focuses on standardized extracts of the root, which concentrate the plant's bioactive compounds for consistent dosing. The ingredient has been reviewed extensively: the Natural Standard Research Collaboration published an evidence-based systematic review covering pharmacology, human clinical evidence, interactions, and safety.13 A 2017 systematic review of 11 human clinical studies concluded there is "convincing evidence" supporting Tongkat Ali's role in male sexual health.10 Most commercial preparations are standardized hot-water root extracts or freeze-dried water extracts, typically used at 200-400 mg per day in trials.
It is worth noting upfront that while the ingredient has a promising research profile, most individual trials are small to moderate in size, and the broader evidence base is still developing. Where evidence is strong, this article says so; where it is preliminary, it says that too.
How Does Tongkat Ali Work?
The root of E. longifolia contains several classes of bioactive compounds. The most studied for hormonal effects are quassinoids - particularly eurycomanone - along with eurypeptides, glycosaponins, and polysaccharides. Current evidence points to at least two complementary mechanisms by which the extract may support testosterone levels in men.
Stimulation of the Hypothalamic-Pituitary-Gonadal (HPG) Axis
Bioactive constituents in Tongkat Ali appear to promote endogenous testosterone synthesis at the level of Leydig cells in the testes, likely via activation of the hypothalamic-pituitary-gonadal axis. This supports the body's own production rather than introducing exogenous hormones - a meaningful mechanistic distinction from conventional testosterone replacement therapy.9
SHBG Binding and Aromatase Inhibition
Eurycomanone and related quassinoids have been proposed to compete with testosterone for binding to sex hormone-binding globulin (SHBG), the protein that keeps testosterone in an inactive, bound form in the bloodstream. By competing for SHBG binding sites, these compounds may increase the fraction of free, biologically active testosterone available to target tissues. Separately, preclinical research suggests eurycomanone may inhibit aromatase, the enzyme that converts testosterone into estradiol, though this mechanism has not yet been confirmed in human trials.9
These mechanisms help explain why clinical trials consistently show proportionally larger testosterone effects in men with low or borderline baseline levels compared to men whose levels are already within the normal range.1 For men with healthy testosterone, effects - if any - are more modest and less consistent across studies.
Testosterone Support and Hormonal Balance
Supporting healthy testosterone levels - particularly in men experiencing age-related hormonal decline or hypogonadism - is the most studied application of Tongkat Ali and the area with the strongest clinical evidence.
What the research shows
A 2022 systematic review and meta-analysis pooled data from five randomized controlled trials (n = 232 men) and found a statistically significant increase in total serum testosterone in men receiving standardized E. longifolia extract (SMD = 1.352; 95% CI: 0.565 to 2.138; p = 0.001).1 Among hypogonadal men with baseline testosterone below 300 ng/dL, the effect size was even larger (SMD = 1.861; 95% CI: 0.719 to 3.002; p = 0.002).1 The authors noted substantial heterogeneity across studies (I² = 87%) and significant publication bias - meaning results from positive trials are more likely to be published - so effect size estimates should be interpreted with appropriate caution.
In a cohort study of 320 men with late-onset hypogonadism, 76 patients received 200 mg of a standardized water extract daily for one month. Testosterone levels normalized in 90.8% of treated men after one month, compared with 35.5% at baseline. Aging Male Symptoms (AMS) scores also improved significantly (p < 0.0001).2
A randomized, double-blind, placebo-controlled multicentre trial enrolled 105 men aged 50-70 with testosterone below 300 ng/dL. At 12 weeks, both the 100 mg and 200 mg Physta® daily groups showed significant within-group increases in total testosterone. The 200 mg group showed significant improvement as early as week 4. AMS scores and fatigue severity both improved significantly from week 2 onward in both active treatment groups.6
A 12-week RCT of 109 men aged 30-55 taking 300 mg of freeze-dried water extract (PHYSTA) daily found significant improvements in erectile function scores and physical functioning quality of life, and a 14% increase in libido by week 12.5
A five-week pilot study of 25 physically active seniors (13 men, 12 women, ages 57-72) supplementing with 400 mg daily reported significant increases in both total and free testosterone concentrations and muscular force in men and women. Male participants also showed increases in hemoglobin and erythrocyte counts.7
- Bottom line: The most consistent clinical benefit is in men with low or low-normal testosterone. The evidence tier for this outcome is Tier A (human RCT and meta-analysis). Effects in men with testosterone already in the healthy range are less well-established, and the research base - while the strongest available for this ingredient - still consists primarily of small to moderate-sized trials with noted publication bias.
Stress Hormones, Cortisol, and Mood
An often-overlooked area of Tongkat Ali research is its potential as an adaptogen - a substance that may help the body manage chronic low-grade stress. This is more than a peripheral claim: the hypothalamic-pituitary-gonadal (HPG) axis and the hypothalamic-pituitary-adrenal (HPA) axis, which governs cortisol release, are closely interrelated. Sustained elevated cortisol is known to suppress testosterone production, and Tongkat Ali may act on both axes simultaneously.
What the research shows
A randomized, placebo-controlled trial enrolled 63 moderately stressed adults (32 men, 31 women) who received either 200 mg of standardized Tongkat Ali hot-water root extract or placebo daily for four weeks. Participants were screened for moderate stress levels (not clinical anxiety or depression). Compared to placebo, the Tongkat Ali group showed statistically significant changes across all measured stress and mood markers:3
- Salivary cortisol reduced by 16% (a meaningful decrease within the normal physiological range)
- Salivary testosterone increased by 37%
- Tension reduced by 11%, anger by 12%, and confusion by 15% on the validated Profile of Mood States (POMS) questionnaire
The authors concluded that the extract "improves stress hormone profile and certain mood state parameters" in people experiencing everyday chronic stress from sources including workload, dieting, sleep deprivation, and exercise training.3
- Bottom line: This is a single well-designed RCT in a mixed-sex sample. Replication in larger independent trials is needed before firm conclusions can be drawn. The findings are mechanistically plausible and represent a meaningful direction for future research. This is a Tier A signal from one study - encouraging but not yet definitive.
Male Fertility and Sperm Quality
Beyond testosterone, Tongkat Ali has been evaluated for its potential to support male reproductive function - specifically, whether it may help maintain healthy semen parameters in men facing fertility challenges.
What the research shows
A prospective clinical study enrolled 350 men with idiopathic male infertility (unexplained poor semen parameters). Participants received 200 mg of standardized Tongkat Ali extract daily and underwent semen analyses every three months for up to nine months. Among those completing a full treatment cycle, all measured semen parameters improved significantly - including volume, sperm concentration, percentage of normal morphology, and motility. Notably, 11 of 75 partners (14.7%) achieved spontaneous pregnancy during the observation period.4 This study did not include a placebo control group, which limits the strength of interpretation.
The 12-week PHYSTA RCT (n = 109 men, ages 30-55) also reported sperm motility improvements of 44.4% and semen volume increases of 18.2% in the subgroup of men with lower baseline sperm values, compared to placebo.5
A 2017 systematic review of 11 human clinical studies concluded that most reported a "remarkable association" between Eurycoma longifolia use and efficacy in supporting male sexual health, including fertility-related semen parameters.10 A 2015 meta-analysis of two RCTs examining erectile function found modest improvement in mild-to-moderate cases, though the pooled effect across both trials did not reach statistical significance - reinforcing that individual responses and baseline severity matter.8
- Bottom line: Evidence for semen parameter support is encouraging, particularly in men with existing fertility challenges. The strongest individual study (Tambi and Imran, 2010) lacks a placebo arm, so caution in interpretation is appropriate. Combined with supportive RCT data, the overall evidence is Tier A in direction but with notable study limitations.
Safety, Side Effects, and Interactions
Tongkat Ali is generally well-tolerated in short-term clinical trials at doses of 200-400 mg per day of standardized extract. A comprehensive preclinical toxicology evaluation found no mutagenicity, no clastogenicity (chromosome-breaking activity), and no test-compound-related organ toxicity over a 13-week exposure period in animal models, with the acceptable daily intake for adults calculated at approximately 1.2 g/day - roughly 12 times the typical human supplementation dose.11 Human RCTs have consistently reported no serious treatment-related adverse events.56
Reported side effects
- Mild gastrointestinal symptoms (nausea, stomach discomfort): the most commonly noted adverse effects in clinical trials; generally mild and self-resolving.
- Restlessness or sleep disruption at higher doses: likely related to increased androgenic activity or mild central stimulation; typically dose-dependent and reversible.
- Liver injury (rare): Case reports of clinically apparent liver injury - including in bodybuilders using high-dose or combination herbal stacks - have been documented and are reviewed in the NIH LiverTox database.14 Causality is difficult to establish when multiple products are co-ingested, but the signal is real. Individuals with pre-existing liver conditions should consult a healthcare provider before use and should discontinue and seek medical evaluation if symptoms of liver injury appear (yellowing of skin/eyes, dark urine, upper-right abdominal pain).
Contraindications and special populations
- Pregnancy and breastfeeding: Safety has not been established. Use is not recommended during pregnancy or while nursing.
- Hormone-sensitive cancers: Because Tongkat Ali may support testosterone production, individuals with hormone-sensitive cancers (e.g., prostate cancer, some breast cancers) should avoid use without explicit physician approval.
- Testosterone replacement therapy (TRT) or other androgen therapies: Combining Tongkat Ali with exogenous hormones may amplify hormonal effects unpredictably. Disclose use to your prescribing provider.
- Anticoagulants and blood thinners: Preclinical data suggest possible effects on prothrombin and partial thromboplastin time.11 Use with caution if taking anticoagulant medications; inform your healthcare provider.
- Antidiabetic medications: Preclinical evidence and some review data suggest possible glucose-regulatory activity.13 Monitor blood glucose if combining with diabetes medications.
Product quality and heavy metals
Standardized root extracts from verified suppliers with third-party heavy-metal testing are strongly preferred. Historically, some Southeast Asian herbal products - including Tongkat Ali preparations - have been found to contain elevated levels of lead and mercury. Look for products with certificates of analysis from independent laboratories.13
Long-term safety
Most human trials have lasted 4-12 weeks. Data beyond 12 weeks in humans are very limited. Long-term safety cannot be confirmed from available evidence, and periodic re-evaluation with a healthcare provider is prudent for ongoing use.
Tongkat Ali Dosage Guide
Doses below are drawn from human clinical trials using standardized hot-water or freeze-dried aqueous root extracts. Unstandardized powders, tinctures, or extracts of unknown concentration may differ substantially in potency. Always follow the dosage recommended on your specific product's label and consult a healthcare provider about what is appropriate for your situation.
| Goal | Typical Dose | Timing | Notes |
|---|---|---|---|
| General testosterone and hormonal support (adult men) | 200 mg/day | Once daily with food | Most commonly used dose in RCTs; standardized water extract preferred; minimum 4-12 weeks to assess benefit |
| Stress hormone and mood support | 200 mg/day | Once daily with food; allow at least 4 weeks | Based on Talbott et al. 2013 RCT in moderately stressed adults (both sexes); cortisol and mood improvements observed at 4 weeks |
| Testosterone support in aging men with low T (50-70 yrs) | 100-200 mg/day | Once daily with food for 12 weeks | Both doses significantly increased testosterone vs baseline in RCT; 200 mg showed earlier onset (week 4); consult physician if clinically hypogonadal |
| Male fertility support | 200-300 mg/day | Daily; minimum 3-month trial | Improvements in sperm concentration, motility, and morphology seen over 3-9 months in clinical studies; partner pregnancy rate 14.7% in open study |
| Physically active older adults | 400 mg/day | Daily for at least 5 weeks | Based on a 25-person pilot study; increases in free and total testosterone and muscular force observed; larger confirmatory trials needed |
No dose has been established specifically for women. The Henkel 2014 pilot study used 400 mg/day in active women aged 57-72 and reported significant increases in testosterone and muscular force, but this was a small pilot study (n=12 women) and female-specific dosing guidance is not established. Women who are pregnant or breastfeeding should not use Tongkat Ali.
What the Evidence Shows at a Glance
A summary of outcomes studied in human clinical trials, the key findings, and the strength of evidence for each.
| Outcome | What Studies Show | Evidence Strength |
|---|---|---|
| Total testosterone (serum) | Significant increase in 5-RCT meta-analysis (SMD = 1.35, p = 0.001); effect largest in hypogonadal men (baseline T < 300 ng/dL) | Tier A - Human RCT / meta-analysis |
| Free testosterone | Significant increases reported in multiple RCTs, including a 5-week pilot in active seniors (400 mg/day) | Tier A - Human RCT |
| Salivary cortisol | 16% reduction vs placebo in a 4-week RCT of 63 moderately stressed adults (200 mg/day) | Tier A - Single RCT; needs replication |
| Mood (tension, anger, confusion) | Significant reductions in all three POMS domains in the same 4-week RCT | Tier A - Single RCT; needs replication |
| Sperm motility and concentration | 44% increase in motility and 18% increase in semen volume (subgroup with low baseline); 14.7% spontaneous pregnancy rate in open fertility study | Tier A with limitations - RCT subgroup + open cohort; no placebo in largest study |
| Sexual libido | 14% increase over 12 weeks in PHYSTA RCT (n = 109 men, 300 mg/day) | Tier A - Human RCT |
| Erectile function | Modest improvement in mild-to-moderate cases; pooled effect across 2 RCTs did not reach statistical significance overall | Tier A - Mixed / modest; insufficient data |
| Muscle strength and force | Positive signal in 5-week senior pilot (400 mg/day); mixed or null results in trained athletes | Tier B - Limited, mixed RCT data |
Tier A = human RCT or systematic review/meta-analysis. Tier B = human observational or limited RCT evidence. Tier C = animal or in vitro only; human evidence not established.
Frequently Asked Questions
What is Tongkat Ali good for?
Tongkat Ali is most studied for supporting healthy testosterone levels in men, particularly those with low or declining testosterone. Clinical research also suggests it may help maintain healthy cortisol levels within the normal range (stress management) and support semen parameters in men facing fertility challenges. Evidence is strongest for men with documented low testosterone.
Does Tongkat Ali actually increase testosterone?
Clinical research suggests yes, particularly in men with low or low-normal baseline testosterone. A 2022 meta-analysis of five RCTs found a statistically significant increase in total testosterone (p = 0.001), with the largest effect in men with baseline levels below 300 ng/dL. Effects in men with already-healthy testosterone are less consistent across studies.
How much Tongkat Ali should I take?
Most clinical trials use 200-400 mg per day of a standardized hot-water or freeze-dried aqueous root extract. The 200 mg dose is the most studied for testosterone and mood support; 400 mg has been used in older active adults. Always use a standardized extract with verified concentration, and follow label guidance on your specific product.
How long does Tongkat Ali take to work?
Most clinical trials run 4-12 weeks. In the Chinnappan 2021 RCT of aging men, the 200 mg group showed significant testosterone increases as early as week 4. Stress and mood improvements were seen at week 4 in the Talbott 2013 RCT. Semen parameter improvements in fertility studies took 3+ months to manifest fully.
Is Tongkat Ali safe?
Short-term use (4-12 weeks) at 200-400 mg/day appears safe in clinical trials, with no serious treatment-related adverse events reported. Rare case reports of liver injury have appeared in the literature, primarily in bodybuilders using high-dose or multi-supplement stacks. Long-term safety data beyond 12 weeks are limited. Consult a healthcare provider before use.
What are the side effects of Tongkat Ali?
The most commonly reported side effects in trials are mild, self-resolving gastrointestinal symptoms (nausea, stomach discomfort) and occasional restlessness or sleep disruption at higher doses. Rare case reports of liver injury exist. Discontinue and see a provider if you develop yellowing of the skin or eyes, dark urine, or upper-right abdominal pain.
Can women take Tongkat Ali?
A small pilot study (n=12 women, ages 57-72) found significant increases in testosterone and muscular force with 400 mg daily for five weeks. Women who are pregnant or breastfeeding should not use Tongkat Ali; safety in pregnancy has not been established. Female-specific dosing guidance does not yet exist from large trials. Consult a healthcare provider.
Does Tongkat Ali help with erectile dysfunction?
Evidence is modest and mixed. A 2015 meta-analysis of two RCTs (139 total participants) found improvement in men with mild-to-moderate cases but no statistically significant overall effect versus placebo. The 12-week PHYSTA RCT reported significant improvements in erectile function scores (p < 0.001). More large-scale trials are needed before definitive conclusions can be drawn.
What is the difference between Tongkat Ali and ashwagandha?
Both are herbal supplements with RCT evidence for supporting testosterone and reducing cortisol, but their mechanisms differ. Tongkat Ali (Eurycoma longifolia) works primarily via quassinoids that may stimulate the HPG axis and reduce SHBG binding. Ashwagandha (Withania somnifera) is a well-studied adaptogen that reduces cortisol via the HPA axis. They are sometimes combined, but head-to-head comparison trials are lacking.
Can I take Tongkat Ali if I am on testosterone replacement therapy?
Combining Tongkat Ali with exogenous testosterone or other androgen therapies may amplify hormonal effects in unpredictable ways and has not been studied in this context. Always disclose all supplements to your prescribing provider before starting. Do not use Tongkat Ali as a substitute for medically supervised hormone therapy without physician guidance.
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Scientific References
- 1.Leisegang K, Finelli R, Sikka SC, Panner Selvam MK Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials. Medicina (Kaunas). 2022. PubMed: 36013514Clinical (RCT / meta-analysis)
- 2.Tambi MI, Imran MK, Henkel RR Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism?. Andrologia. 2012. PubMed: 21671978Clinical (RCT / meta-analysis)
- 3.Talbott SM, Talbott JA, George A, Pugh M Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects. Journal of the International Society of Sports Nutrition. 2013. PubMed: 23705671Clinical (RCT / meta-analysis)
- 4.Tambi MI, Imran MK Eurycoma longifolia Jack in managing idiopathic male infertility. Asian Journal of Andrology. 2010. PubMed: 20348942Clinical (RCT / meta-analysis)
- 5.Ismail SB, Wan Mohammad WMZ, George A, Nik Hussain NH, Musthapa Kamal ZM, Liske E 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. Evidence-Based Complementary and Alternative Medicine. 2012. PubMed: 23243445Clinical (RCT / meta-analysis)
- 6.Chinnappan SM, George A, Pandey P, Narke G, Choudhary YK Effect of Eurycoma longifolia standardised aqueous root extract-Physta® on testosterone levels and quality of life in ageing male subjects: a randomised, double-blind, placebo-controlled multicentre study. Food and Nutrition Research. 2021. PubMed: 34262417Clinical (RCT / meta-analysis)
- 7.Henkel RR, Wang R, Bassett SH, Chen T, Liu N, Zhu Y, Tambi MI Tongkat Ali as a potential herbal supplement for physically active male and female seniors--a pilot study. Phytotherapy Research. 2014. PubMed: 23754792Clinical (RCT / meta-analysis)
- 8.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. Complementary Therapies in Medicine. 2015. PubMed: 26365449Clinical (RCT / meta-analysis)
- 9.George A, Henkel R Phytoandrogenic properties of Eurycoma longifolia as natural alternative to testosterone replacement therapy. Andrologia. 2014. PubMed: 24386995Human observational
- 10.Thu HE, Mohamed IN, Hussain Z, Jayusman PA, Shuid AN Eurycoma Longifolia as a potential adoptogen of male sexual health: a systematic review on clinical studies. Chinese Journal of Natural Medicines. 2017. PubMed: 28259255Clinical (RCT / meta-analysis)
- 11.Li CH, Liao JW, Liao PL, Huang WK, Tse LS, Lin CH, Kang JJ, Cheng YW Evaluation of Acute 13-Week Subchronic Toxicity and Genotoxicity of the Powdered Root of Tongkat Ali (Eurycoma longifolia Jack). Evidence-Based Complementary and Alternative Medicine. 2013. PubMed: 24062779Preclinical (animal / cell)
- 12.Khanijo T, Jiraungkoorskul W Review Ergogenic Effect of Long Jack, Eurycoma longifolia. Pharmacognosy Reviews. 2016. PubMed: 28082797Human observational
- 13.Ulbricht C, Conquer J, Flanagan K, Isaac R, Rusie E, Windsor RC An evidence-based systematic review of tongkat ali (Eurycoma longifolia) by the Natural Standard Research Collaboration. Journal of Dietary Supplements. 2013. PubMed: 23419023Clinical (RCT / meta-analysis)
- 14.National Institute of Diabetes and Digestive and Kidney Diseases Tongkat Ali. In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. NCBI Bookshelf (LiverTox). 2024. PubMed: 39527684Human observational