Tongkat ali

What it is

Tongkat ali comes from the roots of Eurycoma longifolia, a shrub native to Malaysia, Indonesia and surrounding countries. It has long been used in traditional medicine for fatigue, fever and sexual vitality.

Today it is mainly marketed to men for testosterone support, libido, muscle and stress. Women sometimes take it for mood and energy, though there is less data.

In the UK it is sold as a supplement, though regulatory status has been questioned in some places because it is a novel food in the EU context. Check current guidance.

How it works

It may reduce the binding of testosterone to proteins in the blood (raising free testosterone) and may affect cortisol, according to small studies. The mechanism in humans is not well confirmed.

What the evidence says

• Limited Testosterone in men with low levels
  Small studies in older or stressed men show modest increases in testosterone; these are not high-quality enough to be definitive.
• Limited Stress and mood
  A small trial reported lower cortisol and better mood scores over a few weeks.
• Limited Libido and erectile function
  Some small studies show improved sexual wellbeing, with modest effect.
• Weak Muscle and strength
  Mixed results, with any effect likely small compared to training and diet.

Evidence ratings are our plain-English summary of how much good human research exists, not a promise of results. How we rate evidence.

Dosage and timing

• Studies commonly use 200 to 400 mg daily of a standardised water extract.
• Some people take it in cycles, for example five days on and two off, or several weeks on and a break; there is no firm evidence for any pattern.
• Take with a meal if it upsets your stomach.
• There is no NHS reference intake. Check current guidance and the label.

Forms and what to look for

• Standardised water extracts (often 100:1 or 200:1) are used in most research.
• Look for stated eurycomanoside or eurypeptide content.
• Raw powder or bark is hard to dose and quality is variable.
• Avoid products that do not name the species.

What to expect, and when

• Trials usually run for 4 to 12 weeks.
• Any effect on libido or mood may be noticed after a few weeks.
• No change after a couple of months suggests it is not working for you.

Side effects

• Trouble sleeping, restlessness or irritability.
• Increased heart rate or palpitations in some people.
• Headache or nausea.
• Increased aggression or anxiety anecdotally reported.

Interactions

• Testosterone therapy or other hormonal treatments: effects unknown.
• Blood pressure medicines and diabetes medicines: potential interaction.
• Stimulants: additive jitteriness.
• Immunosuppressants: possible interaction.

Who should avoid it

• People with hormone-sensitive cancers, such as prostate or breast cancer.
• Pregnant or breastfeeding women.
• Anyone with heart rhythm problems or high blood pressure, without advice.
• Men trying to conceive, since effects on fertility are not clear.

Risks and safety

• Heavy metal contamination (mercury, lead) has been reported in some tongkat ali products.
• Adulteration with prescription erectile drugs such as sildenafil or tadalafil has been found in some herbal sexual enhancement products generally.
• Not named on the WADA list, but contaminants could cause a positive test.

Buying well: quality and testing

• Choose products with Eurycoma longifolia named and standardised extract ratio.
• Look for third-party test results covering heavy metals and adulterants.
• Be wary of unusually cheap or aggressively marketed products.
• Avoid products with unnamed blends or exaggerated claims.

Bottom line

Tongkat ali has some intriguing small studies, but it is not a proven way to raise testosterone. It might suit an adult wanting a short trial of a standardised, tested extract. If you suspect low testosterone, a GP blood test is a more useful first step than a supplement.