Tongkat Ali
Eurycoma longifolia
TL;DR
A Southeast Asian root extract studied for stress, testosterone and libido. Small RCTs show modest testosterone rises in men with low baseline levels and reduced cortisol under stress; heavy-metal contamination is a real quality issue.
Ideal For
- Men with clinically confirmed low or low-normal testosterone
- High perceived stress with fatigue and low mood
- Age-related decline in libido, after ruling out treatable causes
- Athletes seeking a better testosterone-to-cortisol ratio during heavy training blocks
Avoid If
- Hormone-sensitive cancer, including prostate cancer
- Pregnant, breastfeeding, or trying to conceive as the female partner
- Taking testosterone replacement therapy or other hormone modulation
- Existing liver or kidney disease
- The product has no third-party heavy-metal testing
Frequently Asked Questions
Overview
Tongkat ali (Eurycoma longifolia, also called longjack) is a shrub native to Malaysia and Indonesia whose root has been used traditionally as a tonic for fatigue and male vitality. The bioactive fraction contains quassinoids — eurycomanone chief among them — along with eurypeptides, and commercial extracts are usually standardised as water-soluble concentrates at a 1:50 or 1:100 ratio.
The most cited clinical work is a small trial in moderately stressed adults where 200 mg daily of a standardised water extract lowered salivary cortisol and improved tension, anger and confusion scores over four weeks. Separate trials in men with late-onset hypogonadism or low baseline testosterone have reported increases in total and free testosterone, with a 2022 meta-analysis finding a statistically significant but modest effect that was clearest where baseline levels were low. In eugonadal men — men whose testosterone is already normal — results are much less consistent, and several trials show no change.
There are also small studies on erectile function, sperm quality, muscle strength and endurance performance, generally positive but underpowered and frequently industry-funded. A separate practical concern is quality: independent testing has repeatedly found mercury and lead above acceptable limits in some Malaysian root products, so third-party testing matters more here than for most supplements.
How It Works
- Eurycomanone appears to inhibit aromatase, reducing conversion of testosterone to estradiol and shifting the androgen-to-estrogen ratio
- May reduce sex hormone-binding globulin activity, raising the free fraction of circulating testosterone
- Stimulates steroidogenesis in Leydig cells in animal models via cAMP and StAR protein upregulation
- Lowers salivary and serum cortisol under psychological stress, improving the testosterone-to-cortisol ratio
- Quassinoids show antioxidant and anti-inflammatory activity in vitro, proposed to support Leydig cell function
Quick Facts
- Increases free testosterone
- Reduces stress hormones
- Improves strength and muscle
- Enhances libido and fertility
- Supports mood and energy
Benefits & Outcomes
Testosterone Support
Tongkat ali may help stressed or hypogonadal men, with little effect in healthy men.
Libido Enhancement
Tongkat ali has the best human trial evidence for libido, improving sexual well-being and testosterone in stressed and aging men.
Sexual Arousal
Tongkat ali has better trial support than most libido supplements, particularly in stressed or older men.
Erectile Function
Interesting for libido and stress; erectile-specific evidence is insufficient.
Free Testosterone Increase
Free testosterone rises most reliably in men with low baseline levels or elevated stress.
Stress Resilience
The clearest human signal for tongkat ali is cortisol reduction under stress.
Enhanced Athletic Performance
Performance data are limited to small trials with mixed outcomes.
Reproductive Health
Semen parameters improved in men with idiopathic infertility in a single-arm study.
Mood Stabilization
Mood effects are secondary findings in small stress trials.
Supporting Research7 studies
Efficacy of Tongkat Ali (Eurycoma longifolia) on erectile function improvement: systematic review and meta-analysis of randomized controlled trials
Leisegang K, Sengupta P, Agarwal A +1 more
Pooled analysis of randomised trials of Eurycoma longifolia (Tongkat Ali) found small improvements in erectile function scores and some testosterone-related parameters versus placebo, but effects were inconsistent across trials and largely limited to men with baseline hypogonadism or stress-related low testosterone.
Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials
Leitao AE, Vieira MCS, Pelegrini A
Eurycoma longifolia supplementation significantly increased serum total testosterone, particularly in men with baseline deficiency
A 6-month, double-blind, placebo-controlled, randomized trial to evaluate the effect of Eurycoma longifolia (Tongkat Ali) and concurrent training on erectile function and testosterone levels in androgen deficiency of aging males (ADAM)
Leitao AE, Vieira MCS, Pelegrini A +2 more
Eurycoma longifolia with concurrent training improved erectile function and testosterone over six months
The effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects
Talbott SM, Talbott JA, George A +1 more
Supplementation reduced salivary cortisol and improved tension, anger and confusion in moderately stressed adults
Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects
Talbott SM, Talbott JA, George A +1 more
Supplementation reduced salivary cortisol and improved tension, anger and confusion in moderately stressed adults
Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism?
Tambi MI, Imran MK, Henkel RR
Ageing Male Symptom scores improved and serum testosterone normalised in most participants
An Evidence-Based Systematic Review of Tongkat Ali (Eurycoma longifolia) by the Natural Standard Research Collaboration
Ulbricht C, Conquer J, Flanagan K
Human evidence for tongkat ali was graded weak for all reviewed indications
Safety Information
Potential Side Effects
Usually well tolerated at 200-400 mg. Reported effects include insomnia or restlessness (especially with evening dosing), irritability, mild GI upset, headache and increased body temperature. Rare case reports describe liver injury, though causality is unclear and contamination cannot be excluded. Its hormonal activity makes it inappropriate in pregnancy and breastfeeding.
Contraindications
Avoid in prostate cancer and other hormone-sensitive cancers, in liver or kidney disease, and in pregnancy or breastfeeding. Do not combine with testosterone replacement therapy without endocrinology input. Independent testing has found mercury and lead above safety limits in some products — insist on a certificate of analysis. Long-term safety beyond roughly nine months of continuous use has not been established.
Drug Interactions
- Testosterone replacement therapy and anabolic agents — additive hormonal effect; do not combine unsupervised
- Antihypertensives — small studies report modest blood pressure changes; monitor if your pressure is controlled
- Antidiabetic medication — animal data suggest a glucose-lowering effect; watch for hypoglycaemia
- Propranolol — absorption may be reduced when taken together; separate doses
- Immunosuppressants — immunostimulatory activity has been reported in vitro and may work against therapy
Pregnancy & Breastfeeding
Pregnancy: likely_unsafe
Breastfeeding: likely_unsafe
Dosage Guidelines
Dosage Used in Studies
200-400 mg
Best Time to Take
Morning — a subset of users report sleep disturbance or restlessness when taken in the evening
Best Form
A third-party tested water-soluble root extract standardised for eurycomanone, at 200-400 mg daily
Bioavailability
Contains eurycomanone and other quassinoids. May increase testosterone in men with low levels. Adaptogenic properties. Effects develop over 4-8 weeks. Cycling recommended.
Dosing by Goal
| Goal | Dose | Notes |
|---|---|---|
| Stress and cortisol | 200 mg daily of standardised water extract | The dose from the moderately-stressed-adults trial. Outcomes were measured at four weeks. |
| Low testosterone support | 200-400 mg daily | Most trials run 4-12 weeks. Effects are clearest in men with low baseline testosterone; expect little if levels are already normal. |
| Libido and erectile function | 200-300 mg daily | Small trials, generally 12 weeks. Not a substitute for evaluating an underlying cause. |
| Cycling | Consider 8-12 weeks on, then a break | Long-term safety data beyond about nine months are limited, so periodic breaks and re-evaluation are sensible. |
Forms Compared
Water-soluble root extract 1:50
Best for Most clinical use
Corresponds to the material used in the stress and testosterone trials, typically dosed at 200-400 mg. Look for eurycomanone standardisation.
Standardised eurycomanone extract
Best for Dose consistency
Standardised to 1-2% eurycomanone. Easier to compare between products, but potency claims vary widely.
Raw root powder
Best for Traditional preparation
Far weaker per gram and the least consistent option. Also the form most associated with heavy-metal contamination reports.
Combination testosterone formulas
Best for Not recommended
Often stacked with tribulus or fenugreek, making it impossible to attribute any effect or to control the dose.
Food & Timing
Can be taken with or without food. Some people find it easier on the stomach with a meal.
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.