Tongkat Ali: Benefits, Dosage, Best Forms & Safety

What Is Tongkat Ali?

Tongkat ali (Eurycoma longifolia), also called longjack, is a shrub native to Southeast Asia, including Malaysia, Indonesia, and Vietnam, where its root has a long history of traditional use as an energy tonic and aphrodisiac. Its bioactive compounds include eurycomanone and related quassinoids, which are the focus of most modern research.

Modern interest centers on its potential to raise testosterone, particularly in men with clinically low levels. It is now frequently marketed alongside newer ingredients like Fadogia agrestis (see our Fadogia Agrestis guide) and compared against other adaptogens like ashwagandha (see our Ashwagandha vs. Tongkat Ali comparison).

What the Evidence Says

• Testosterone, especially in men with low baseline levels. A meta-analysis of randomized controlled trials found tongkat ali supplementation (100-600 mg/day for 2-12 weeks) significantly increased testosterone, with the effect appearing stronger in men who started with lower testosterone levels than in men with already-normal levels. The same analysis noted meaningful publication bias across the available studies, meaning the true average effect may be smaller than it appears.
• Libido and sexual function (modest, limited human data). A human trial using 300 mg/day of a water extract for 6-12 weeks reported a modest increase in libido, roughly 8 to 11% relative to baseline. Most of the supporting mechanistic and aphrodisiac-effect research otherwise comes from animal studies.
• Mood and perceived stress (weak evidence). A small number of studies, including at least one human trial, report improved self-reported stress or mood scores over several weeks, but this evidence base is thin compared with the testosterone research.
• Sperm parameters (preliminary). Some studies report improvements in sperm count and morphology, though this research is again limited in scope compared with the testosterone data.

Dosage Guide

• Standard Dose: 200-400 mg/day of standardized root extract is the range most often used for testosterone- and libido-related outcomes in human trials; clinical research overall spans roughly 100-600 mg/day, taken once daily or split into two doses.
• Upper Limit (UL): No official UL has been established by NIH ODS; tongkat ali is not an essential nutrient. Human trials have generally used short-term protocols of 2 to 12 weeks, so data on continuous long-term use is limited.
• Timing: Most studied protocols use once-daily or twice-daily dosing with food.
• Notes: Look for products standardized to a known eurycomanone content or a validated extract ratio. Unstandardized raw root powder makes it hard to know what dose is actually being taken.

Drug & Supplement Interactions

• Liver conditions or liver-affecting medications (Medium): The NIH-affiliated LiverTox database rates tongkat ali as a possible, rare cause of clinically apparent liver injury, including at least one case report of jaundice in a supplement user, though that case was confounded by undisclosed anabolic steroid use. People with existing liver disease should be cautious and watch for symptoms like jaundice, dark urine, or abdominal pain.
• Diabetes medication and blood sugar monitoring (Low, evidence inconclusive): Some marketing claims suggest tongkat ali lowers blood sugar, but the controlled research that has specifically measured blood glucose has not confirmed a meaningful effect. Because reliable long-term interaction data doesn’t exist either way, anyone on insulin or other glucose-lowering medication should monitor blood sugar and talk to their doctor before combining them, rather than assuming a beneficial effect.
• Hormone therapy or hormone-sensitive cancer history (Medium): Because tongkat ali’s best-supported effect is raising testosterone, anyone on prescribed hormone therapy or with a personal history of a hormone-sensitive cancer should talk to a doctor before use.
• Blood pressure medication, e.g., propranolol (Low, limited data): At least one source flags a possible interaction with propranolol. The evidence behind this is limited, but it is a reasonable reason to mention tongkat ali use to a prescriber.

Safety & Side Effects

At the doses used in clinical trials, reported side effects have been mild and uncommon: nausea, abdominal discomfort, diarrhea, headache, and itching or rash. A 2021 European Food Safety Authority (EFSA) opinion on a specific tongkat ali extract flagged a potential for DNA damage in animal genotoxicity testing at high doses, a signal that has led to some regulatory caution in the EU, though it has not been confirmed as a human health risk at typical supplemental doses.

As with several herbal test-boosters, product quality varies. Heavy-metal contamination (lead, mercury) has been documented in some tongkat ali products sourced from Southeast Asia, and some products have been found adulterated with undeclared prescription drugs such as sildenafil. Choosing a reputable brand with third-party testing reduces, but does not eliminate, this risk.

Bottom Line

Tongkat ali is one of the better-supported ingredients in the current wave of natural testosterone-support supplements, largely thanks to a meta-analysis showing a real testosterone increase, especially in men with low baseline levels. That said, publication bias in the underlying studies, thinner evidence for libido and mood claims, and unresolved questions about long-term safety and product purity mean it should be approached as a promising, not fully proven, option rather than a guaranteed fix.

Frequently Asked Questions

Q: Does tongkat ali actually raise testosterone?
A: A meta-analysis of randomized controlled trials found it does, particularly in men with low baseline testosterone, at doses of 100-600 mg/day over 2 to 12 weeks. However, the same analysis noted meaningful publication bias, so the true effect size across all available research may be smaller than the average result suggests.

Q: Does tongkat ali lower blood sugar or interact with diabetes medication?
A: This is a common marketing claim, but the controlled research that has directly measured blood glucose has not confirmed a meaningful blood-sugar-lowering effect. Because reliable interaction data with diabetes medications doesn’t exist, anyone with diabetes should discuss it with a doctor and monitor blood sugar rather than relying on this claim.

Q: Is tongkat ali safe for the liver?
A: At studied doses, most clinical trials found no meaningful change in standard liver enzymes. However, the LiverTox database rates it as a possible, rare cause of liver injury, with at least one reported case of jaundice in a supplement user, a case complicated by undisclosed steroid use. Anyone with existing liver disease should be cautious.

Q: How is tongkat ali different from Fadogia agrestis?
A: Tongkat ali has multiple human clinical trials, including a meta-analysis, behind its testosterone claims. Fadogia agrestis has zero published human trials; its claims come entirely from small rodent studies. See our Fadogia Agrestis guide for the full comparison.

Sources

• Examine.com: Tongkat Ali research summary and evidence-grading breakdown.
• NCBI LiverTox (NIH National Library of Medicine): Tongkat Ali monograph.
• Operation Supplement Safety (OPSS.org, U.S. Department of Defense): “Tongkat Ali: Uses and Safety in Dietary Supplements.”
• European Food Safety Authority (EFSA): 2021 opinion on Eurycoma longifolia extract genotoxicity.