{"ok":true,"entry":{"slug":"tongkat-ali","kind":"supplement","name":"tongkat ali","aliases":["Eurycoma longifolia","longjack"],"brands_sg":["Solaray","Nutricost","Swanson Vitamins","Nature's Truth","NOW Foods"],"class":"botanical","tags":["mens-health","fitness"],"use_for":"total testosterone in men — 5 small rcts pooled","use_after":"timing untested","use_duration":"trials dose daily for 2 weeks to 6 months","take_with":null,"pros":["pooled testosterone rise across 5 rcts (smd 1.35)","trials used 100–600 mg a day of one standard extract","only one trial reported side effects"],"cons":["87% heterogeneity and signs of publication bias","malaysian survey: some products had no eurycomanone","small, short trials; mostly one proprietary extract"],"dose_note":"trials in the 2022 meta-analysis used 100–600 mg a day, most often a standardised water extract (physta), for 2 weeks up to 6 months; a malaysian product survey found eurycomanone content ranging from none to above the recommended level, so a label milligram figure is not comparable across brands","dosage":{"ul":null,"unit":"mg","fda_dv":null,"rda_ai":null,"ul_status":"none_established","population":"general adult","hsa_max_daily":null},"ul_status":"none_established","sg_class":null,"cautions":["hormone-sensitive condition — testosterone rose in the pooled trials; ask your doctor first","product content varies — eurycomanone was absent from some malaysian samples","women, and anyone under 18 — the trials reviewed were in adult men"],"clashes":[],"sources":[{"id":"leisegang2022","url":"https://europepmc.org/article/PMC/PMC9415500","label":"Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials (Leisegang et al., Medicina 2022)","quote":"The random model effect revealed a significant increase (SMD = 1.352, 95% CI 0.565 to 2.138, p = 0.001) in the total testosterone levels in men receiving E. longifolia supplementation","accessed":"2026-08-27"},{"id":"leisegang2022_scope","url":"https://europepmc.org/article/PMC/PMC9415500","label":"Leisegang et al. 2022 — studies included and population","quote":"a total of nine studies was included in the systematic review. Five RCTs were included in the meta-analysis … Five eligible RCTs measuring the testosterone levels in men (n = 232)","accessed":"2026-08-27"},{"id":"leisegang2022_dose","url":"https://europepmc.org/article/PMC/PMC9415500","label":"Leisegang et al. 2022 — Table 1, supplement dosage and treatment length","quote":"Physta, Biotropics 600 mg/day for 2 weeks … Dry extract 200 mg up to 6 months … 100 mg/daily up to 12 weeks … 200 mg/daily up to 12 weeks … 300 mg for 12 weeks","accessed":"2026-08-27"},{"id":"leisegang2022_ae","url":"https://europepmc.org/article/PMC/PMC9415500","label":"Leisegang et al. 2022 — reported adverse effects","quote":"Only one study reported adverse effects associated with E. longifolia treatment, which included gastrointestinal symptoms and itching, while Ismael et al. observed adverse events in both treated and placebo groups","accessed":"2026-08-27"},{"id":"leisegang2022_bias","url":"https://europepmc.org/article/PMC/PMC9415500","label":"Leisegang et al. 2022 — heterogeneity and publication bias","quote":"Tests for heterogeneity implicated heterogeneity across the five studies … with 87.27% inconsistency … a low p value (0.0243) was noticed with Begg's test, indicating publication bias","accessed":"2026-08-27"},{"id":"leisegang2022_quality","url":"https://europepmc.org/article/PMC/PMC9415500","label":"Leisegang et al. 2022 — eurycomanone content of marketed products","quote":"Out of 41 products containing E. longifolia as a single or compound formulation from Malaysia, 24 products contained eurycomanone: 11/24 reached the recommended levels, while 9 were above the recommended levels … Some products did not contain any eurycomanone","accessed":"2026-08-27"},{"id":"leisegang2022_limits","url":"https://europepmc.org/article/PMC/PMC9415500","label":"Leisegang et al. 2022 — stated limitations","quote":"the analysis was based on five studies, which were heterogeneous in terms of study design, included population, dosage and length of treatment, and limited sample sizes","accessed":"2026-08-27"},{"id":"hsa_prohibited_2025","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev 001 (Oct 2025), Annexes A and B — Eurycoma longifolia / tongkat ali / longjack not listed in Annex A or B (full text searched)","quote":"The objective of this guideline is to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list.","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/tongkat-ali","label":"iHerb Singapore — Tongkat Ali category page, default (best-selling) order, SGD pricing; no Singapore shipping-restriction notice shown","quote":"Solaray, Tongkat Ali, 400 mg, 60 VegCaps … Nutricost, Tongkat Ali, 120 Capsules … Swanson Vitamins, Tongkat Ali, 400 mg … Nature's Truth, Longjack Tongkat Ali … NOW Foods, TestoJack 200","accessed":"2026-08-27"}],"brand_certs":null,"updated_at":"2026-08-29T16:16:33.302383+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}