Tongkat Ali (Eurycoma longifolia)
SupplementMinor divergence: Clinical evidence [s1, s7] and community experiences [c1, c2] are largely consistent in the direction and magnitude of effects. The medical assessment places greater weight on extract heterogeneity and contamination risk [s10, s11], while users generally report positive experiences with trusted products [c1, c3].
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TL;DR
Tongkat Ali is the best-evidenced herbal testosterone supplement — a meta-analysis of 5 RCTs (n=293) shows significant testosterone increases, with additional evidence for libido, stress hormones, and aging men. Effects are real but moderate, and most relevant for men with suboptimal hormone status; healthy young men with normal testosterone often report no benefit. Critical point: heavy metal contamination (lead, mercury) is documented in low-quality products — only use extracts with stated eurycomanone content and a verified heavy metal analysis. Industry-funded studies and inconsistent extract standardization limit the strength of the evidence.
Description
Herbal extract from the root of Eurycoma longifolia to support testosterone levels, libido, stress hormone profile, and athletic performance [s1, s2].
Tongkat Ali (Eurycoma longifolia Jack, also known as Longjack or Pasak Bumi) is a shrub native to Southeast Asia whose root has been used for centuries in the traditional medicine of Malaysia and Indonesia [s1]. The pharmaceutically relevant constituents are quassinoids (particularly eurycomanone), canthinone alkaloids, and β-carboline alkaloids [s3]. Clinical studies show that standardized root extracts can significantly increase serum total testosterone levels in men with low baseline values [s1, s4]. A 2022 meta-analysis of five RCTs confirmed this effect in both healthy men and those with hypogonadism [s1]. Additionally, improvements in libido, erectile function, sperm quality, and sperm motility have been documented in clinical studies [s5, s6]. As an adaptogen, Tongkat Ali lowers the stress hormone cortisol and improves the testosterone/cortisol ratio [s7]. A placebo-controlled study in moderately stressed subjects measured a 16% reduction in cortisol and a 37% increase in testosterone [s7]. The standardized extracts Physta (freeze-dried water extract) and LJ100 (water-extracted concentrate, 22:1) have been particularly extensively studied [s8, s9]. The evidence base for women is considerably thinner than for men [s5]. The safety profile is generally favorable with short- to medium-term use; however, there is a documented risk of heavy metal contamination (lead, mercury) with low-quality products [s10, s11].
Legal Status (DE)
In Germany, Tongkat Ali is generally marketable as a food supplement (NEM), provided it is classified as a conventional food with a history of use prior to 1997. The EFSA evaluated a standardized root extract in 2021 under the Novel Food Regulation (EU) 2015/2283 [s12]. Products without a documented history of use prior to 1997 may be considered novel foods and would then require EU authorization. Marketing as a food supplement without specific health claims is widespread in practice [s12, s13].
Mechanism of Action
Tongkat Ali acts through several interconnected mechanisms: 1. HPG axis stimulation: Eurycomanone stimulates the hypothalamic-pituitary-gonadal (HPG) axis and increases the release of luteinizing hormone (LH), which stimulates testosterone production in the Leydig cells of the testes [s3]. 2. Aromatase inhibition: Eurycomanone inhibits aromatase activity in Leydig cells, thereby reducing the conversion of testosterone to estrogen [s3]. 3. SHBG binding: Bioactive compounds in Tongkat Ali may compete with testosterone for sex hormone-binding globulin (SHBG) binding sites, resulting in greater circulating free, biologically available testosterone [s3]. 4. Phosphodiesterase inhibition: At high concentrations, eurycomanone inhibits phosphodiesterase activity, increasing cAMP availability in Leydig cells and supporting steroidogenesis [s3]. 5. Cortisol modulation (adaptogenic effect): Tongkat Ali reduces cortisol secretion, presumably via modulation of adrenocortical activity, thereby improving the testosterone/cortisol ratio [s7]. 6. Promotion of spermatogenesis: The combined aromatase inhibition and PDE inhibition also supports spermatogenesis, which in clinical studies led to improvements in sperm motility and morphology [s3, s5].
Dosing
Testosteron- und Libidounterstützung (standardisierter Extrakt)
- Dose
- 200–400 mg standardized root extract (e.g., Physta or LJ100)
- Frequency
- 1× täglich
- Route
- oral
- Duration
- 8–12 Wochen, dann Pause prüfen
- Timing
- Morning with or without meal
- With food
- optional
Stressreduktion / Adaptogen
- Dose
- 200 mg standardized extract
- Frequency
- 1× täglich
- Route
- oral
- Duration
- 4 Wochen
- Timing
- Morning
- With food
- optional
Männliche Fertilitätsunterstützung
- Dose
- 200–300 mg standardized aqueous extract
- Frequency
- 1× täglich
- Route
- oral
- Duration
- 12 Wochen
- Timing
- Morning with meal
- With food
- empfohlen
No officially established maximum daily intake for food supplements in the EU. Clinical studies have used doses up to 600 mg/day. The EFSA assessment is based on a daily intake of 400 mg extract [s12]. Higher doses have not been sufficiently investigated for long-term safety.
Use only standardized, laboratory-certified extracts (eurycomanone content stated, heavy metal analysis available) [s10, s11]. Avoid products without quality certification. Cycling protocols (e.g., 5 days on / 2 days off or 4 weeks on / 1 week off) are practiced by some users but are not supported by RCTs [c1, c2].
Side Effects
| Side Effect | Frequency | Severity |
|---|---|---|
| Schlafstörungen / Insomnie Elevated testosterone and energy levels can disrupt sleep, particularly with evening administration. Frequently mentioned in user reports [c1, c2]. | gelegentlich | leicht |
| Reizbarkeit / erhöhte Aggressivität Possibly mediated by increases in testosterone and DHT. Reported in community accounts at higher doses or with prolonged use [c2, c4]. | gelegentlich | leicht |
| Gastrointestinale Beschwerden (Übelkeit, Magenbeschwerden) Sporadically reported in clinical trials; individual users describe nausea following ingestion [s11, c1]. | gelegentlich | leicht |
| Hautreaktionen Occasionally mentioned in adverse effect reviews, without clear frequency data [s11]. | selten | leicht |
| Schwermetallvergiftung (Blei, Quecksilber) bei kontaminierten Produkten Analysis of 100 Tongkat Ali products from Malaysia revealed mercury contamination. Adulteration with sildenafil has been documented in individual products [s10, s11]. | theoretisch | schwer |
| Libidoverlust / Rebound-Effekt nach Absetzen Individual user reports describe transiently reduced libido after prolonged use and upon discontinuation [c1, c2]. | selten | leicht |
Contraindications
Due to the testosterone-elevating effect, stimulation of hormone-dependent tumors is theoretically possible. No specific studies, but mechanistically plausible [s12].
No safety data in pregnant or breastfeeding women. Animal studies indicate possible developmental toxicity. Use is discouraged [s12].
Insufficient safety data in impaired hepatic or renal function. Increased risk of accumulation of active substances and heavy metals possible [s12].
No safety data available; influence on hormonal system development unresolved [s12].
Preclinical data suggest immunomodulatory effects; interaction with immunosuppressants cannot be excluded [s12].
Interactions
Synergistic
Zinc is a cofactor in testosterone synthesis. The combination may have an additive effect on testosterone in cases of zinc deficiency; not substantiated by combined RCTs [s13].
Both adaptogens target the HPA axis and cortisol reduction. Synergy is mechanistically plausible; clinical combination studies are lacking [c3].
DHEA is a precursor of testosterone; Tongkat Ali increases free testosterone by lowering SHBG. The combination may have additive effects on testosterone production.
DIM supports the metabolism of estrogen toward more favorable metabolites and may inhibit aromatase. Combined with Tongkat Ali, this may improve the testosterone-to-estrogen ratio in men.
Boron may lower SHBG and increase testosterone bioavailability; an additive effect on free testosterone in combination with Tongkat Ali is mechanistically plausible.
Panax ginseng and Tongkat Ali are both adaptogens that promote energy, cognitive function, and stress resilience. A combination may be mutually complementary, particularly for mental clarity and physical endurance.
Fenugreek contains steroidal saponins as testosterone precursors and may inhibit 5α-reductase. Additive effects on testosterone levels in combination with Tongkat Ali are plausible.
Magnesium is a cofactor in testosterone synthesis and may lower SHBG. An additive effect on free testosterone in combination with Tongkat Ali is mechanistically plausible, particularly in cases of magnesium deficiency.
Caution
Additive testosterone-boosting effect; overdose and suppression of the endogenous hormonal axis possible. Combination only under medical supervision [s12].
Preclinical evidence of blood glucose-lowering properties of Eurycoma longifolia; additive hypoglycemia theoretically possible with concurrent diabetes medication [s12].
Immunomodulatory properties may affect the efficacy of immunosuppressants [s12].
Combined intake of DHEA and Tongkat Ali may lead to excessively elevated androgen levels. Individuals with hormone-dependent conditions should seek medical evaluation.
Studies
Tier A — High Evidence
Outcome: Serum total testosterone increase in men
Effect Size: Significant increase; pooled effect size statistically significant (p < 0.05)
Outcome: Cortisol and testosterone changes under moderate stress
Effect Size: Cortisol –16%, testosterone +37% vs. placebo
Outcome: Free testosterone, quality of life in aging men
Effect Size: Significant within-group increase in free testosterone; no significant between-group difference
Outcome: Libido, erectile function, sexual satisfaction
Effect Size: Significant improvements in IIEF and libido scores (p < 0.001)
Tier B — Moderate Evidence
Outcome: Comparison of extract standardizations and dosage recommendations
Effect Size: 200–400 mg/day standardized extract identified as optimal
Outcome: Male sexual health: libido, erectile function, sperm quality, testosterone
Effect Size: Multiple clinical trials demonstrate significant improvements in sperm motility (+44.4%), semen volume (+18.2%), libido (+14%)
Tier C — Low Evidence
Outcome: Aromatase inhibition and PDE inhibition by eurycomanone in Leydig cells
Effect Size: Eurycomanone inhibits aromatase and promotes steroidogenesis
Community Evidence
Top reported benefits
- Increased libido and sexual desire
- Increased energy and drive
- Subjectively improved mood and well-being
- Improved training motivation
- Increase in testosterone levels in blood work
Top reported issues
- Sleep disturbances and difficulty falling asleep, especially with evening administration
- Irritability and increased aggression at higher doses
- No noticeable effect in healthy young men with normal testosterone
- Nausea and gastrointestinal discomfort after ingestion
- Rebound effect (transient low libido after discontinuation)
A recurring theme in the community is product quality: heavy metal contamination and adulteration with sildenafil have been discussed in forums [c3, c4]. Younger men with normal hormonal status more frequently report lack of efficacy. Some users recommend cycling protocols (e.g., 5/2 or 4 weeks on/1 week off) without clinical evidence to support this [c1, c2].
Scientific Sources
- Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials
Leisegang K, Finelli R, Sikka SC, et al. (2022). MedicinaAPMID:36013514DOI - Contamination of mercury in tongkat Ali hitam herbal preparations
Ang HH, Lee KL, Kiyoshi M (2006). Food and Chemical ToxicologyBPMID:16458409DOI - Tongkat ali: Uses and safety in dietary supplements
Operation Supplement Safety (OPSS) (2023). Operation Supplement Safety (HPRC)BLink - Safety of Eurycoma longifolia (Tongkat Ali) root extract as a novel food pursuant to Regulation (EU) 2015/2283
EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, Heinonen M, et al. (2021). EFSA JournalADOI - Fragen und Antworten zu Nahrungsergänzungsmitteln – BfR
Bundesinstitut für Risikobewertung (BfR) (2018). BfRBLink - 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)
Leitão AE, Vieira MCS, Cavalli AS, et al. (2021). MaturitasCDOI - The effect of Eurycoma longifolia on the regulation of reproductive hormones in young males
Chan KQ, Stewart C, Chester N, Hamzah SH, Yusof A (2021). AndrologiaCDOI - The ergogenic effects of Eurycoma longifolia Jack: a pilot study
Hamzah S, Yusof A (2003). British Journal of Sports MedicineC - Effect of Eurycoma longifolia water extract (Physta®) on menopausal quality of life and mood states
Muniandy S, Yahya HM, Shahar S, Kamisan Atan I, Mahdy ZA, Rajab NF, Mohd Rasdi HF, George A, Chinnappan SM (2025). World Journal of Clinical CasesC - Eurycoma longifolia (Tongkat Ali) supplementation enhances sleep and wake consolidation in wild-type, but not in narcoleptic mice
Morishige M, Takeda N, Ono H, et al. (2024). SLEEP AdvancesCDOI - Eurycomanone, the major quassinoid in Eurycoma longifolia root extract increases spermatogenesis by inhibiting the activity of phosphodiesterase and aromatase in steroidogenesis
Wahab NA, Mokhtar NM, Halim WNA, et al. (2010). Journal of EthnopharmacologyCPMID:23608234DOI - 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)
Leitão AE, Vieira MCS, Pelegrini A, et al. (2021). MaturitasAPMID:33581895DOI - Eurycoma Longifolia as a potential adoptogen of male sexual health: a systematic review on clinical studies
Rehman SU, Choe K, Yoo HH (2016). Chinese Journal of Natural MedicinesAPMID:28259255DOI - 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
Ismail SB, Wan Mohammad WMZ, George A, et al. (2012). Evidence-Based Complementary and Alternative MedicineAPMID:23243445DOI - Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects
Talbott SM, Talbott JA, George A, et al. (2013). Journal of the International Society of Sports NutritionAPMID:23705671DOI - 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
Henkel RR, Wang R, Bassett SH, et al. (2014). AndrologiaAPMID:24386995DOI - A Multifaceted Review of Eurycoma longifolia Nutraceutical Bioactives: Production, Extraction, and Analysis in Drugs and Biofluids
Bhat R, Karim AA (2023). ACS OmegaBDOI
Community Sources
Storage
Unopened
Store in a dry, cool place (15–25 °C), protected from direct sunlight and moisture.
Opened
Keep container tightly closed; use the original container for capsule forms.
Notes
Prefer extracts with a known eurycomanone content. Refrigeration is not required unless otherwise specified by the manufacturer.