Tongkat Ali (Longjack): Uses, Benefits, Dosage & Safety

Last updated: June 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy

What is Tongkat Ali (Longjack)?

Tongkat ali (Eurycoma longifolia), also called longjack or 'Malaysian ginseng', is a slow-growing Southeast Asian shrub whose root has a long traditional use as a tonic for energy, libido and male vitality. Its studied active compounds include quassinoids such as eurycomanone. It is marketed for testosterone support, libido, stress resilience and athletic performance, usually as a water extract standardised to eurycomanone content. Because the root takes years to mature and demand is high, adulteration and contamination are recognised problems in the marketplace.

What Tongkat Ali (Longjack) is commonly used for

In supplements, Tongkat Ali (Longjack) is most often included for men's vitality & testosterone support. It is used as nutritional support, not as a treatment for any medical condition — the distinction matters, because the claims on a sales page are often stronger than the evidence allows.

How Tongkat Ali (Longjack) works

Tongkat ali is proposed to support testosterone indirectly — by influencing sex-hormone-binding globulin (SHBG), the protein that ties up testosterone, thereby raising the 'free' fraction — and by moderating the stress hormone cortisol. A better testosterone-to-cortisol balance is the rationale behind its vitality and stress claims. The active compounds have been characterised, but the human evidence connecting them to consistent real-world benefits is still developing.

What the evidence says

Here's an honest snapshot of what published research suggests about Tongkat Ali (Longjack) — including where the evidence is limited.

• Small randomised trials suggest standardised tongkat ali may modestly support testosterone, stress markers, mood and well-being, particularly in older or stressed men, though the studies are small and short. (PubMed research)
• Some studies report improvements in measures of libido and male fertility, with preliminary results. (PubMed research)
• Independent testing has found heavy-metal contamination, including mercury, in some tongkat ali products, making source quality a genuine concern. (PubMed research)

Typical dosage used in studies

Trials have used roughly 200-400 mg/day of a standardised water extract, often for several weeks. This is research information, not a recommendation.

Side effects and safety

Short-term use of quality products is generally well tolerated; insomnia, restlessness and irritability are occasionally reported. The larger safety question is contamination in poorly sourced products rather than the herb itself, and long-term safety data are limited.

Medication interactions and who should avoid Tongkat Ali (Longjack)

Sources & further reading

The evidence summary above is drawn from these sources. For general, authoritative background you can also consult:

• PubMed research
• PubMed research
• PubMed research
• NIH Office of Dietary Supplements
• NIH National Center for Complementary and Integrative Health
• MedlinePlus (U.S. National Library of Medicine)

Frequently asked questions

Does tongkat ali boost testosterone?

Some small trials suggest a modest effect, especially in older or stressed men, via free-testosterone and cortisol pathways. The evidence is limited and shouldn't be oversold.

Is tongkat ali safe?

Quality products are generally tolerated short-term, but heavy-metal contamination has been found in some supplements — choose third-party-tested brands.

What dose is used?

Roughly 200-400 mg/day of a standardised water extract.

Does it help libido or fertility?

Small studies suggest possible benefit, but the results are preliminary.

Who should avoid it?

Anyone with a hormone-sensitive condition, on medication, or pregnant or breastfeeding should check with a doctor first.