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Tongkat ali

The root of a slow-growing Southeast Asian tree, sold mostly as a testosterone supplement for men. Small trials suggest a modest rise in total testosterone; LiverTox records rare reports of liver injury, and surveys have found mercury in some products.

Serious warning

LiverTox lists tongkat ali as a possible rare cause of liver injury, with published cases of jaundice needing hospital care, mostly in body builders. Separately, two surveys of products sold in Malaysia found mercury above the legal limit in about a quarter to a third of those tested.

Traditional use

A shrubby evergreen tree native to Southeast Asia. Its leaves, roots and bark have long been used in traditional medicine there for diabetes, rheumatism, jaundice, malaria, fever, and as an aphrodisiac. In recent years root extracts have become a popular supplement in the United States, sold for testosterone, erectile function, "low T," body building and muscle strength.

What studies show

  • Limited

    Testosterone: a 2022 review of trials in men pooled five randomized studies and found a rise in total testosterone, including in men with low testosterone. LiverTox describes the rise as mild, taking several weeks, with no rise in free testosterone. The review's authors say more research is needed.

  • Insufficient

    Erectile function: a 2015 review found only two randomized trials (139 men); overall there was no clear difference from placebo, and the authors call for more trials.

  • Limited· shows no benefit

    Athletic performance: LiverTox notes that the testosterone changes came with mild gains in muscle strength during resistance training but have not been linked to better athletic performance.

Be careful of

Cautions

  • ConditionLiverTox notes that liver injury may be more frequent and more severe in people with existing liver disease, who were excluded from most studies. Stop and get medical care if you notice dark urine, yellowing of the skin or eyes, nausea, or pain in the upper belly.
  • AmountLiverTox gives 100 to 400 mg a day as the typical traditional amount; products sold online may contain 1,000 to 1,600 mg. The effects of long-term use and of higher doses have not been studied in people.
  • NoteSide effects at usual doses are uncommon but can include nausea, stomach discomfort, diarrhea, headache and rash. Products are not standardized for purity or strength.
  • NoteMercury contamination has been found in tongkat ali products (surveys in Malaysia, 2004 and 2006), and the researchers warn that even products that passed cannot be assumed free of mercury, because batches vary.
  • Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.

Sources

  1. Tongkat Ali (LiverTox) (opens in a new tab) · NIH · read September 25, 2026
  2. Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials (opens in a new tab) · NIH · read September 25, 2026
  3. Efficacy of Tongkat Ali (Eurycoma longifolia) on erectile function improvement: systematic review and meta-analysis of randomized controlled trials (opens in a new tab) · NIH · read September 25, 2026
  4. Determination of mercury by cold vapor atomic absorption spectrophotometer in Tongkat Ali preparations obtained in Malaysia (opens in a new tab) · NIH · read September 25, 2026
  5. Contamination of mercury in tongkat Ali hitam herbal preparations (opens in a new tab) · NIH · read September 25, 2026

Reviewed September 25, 2026.