Tongkat ali has a mixed safety profile. Short-term use at typical supplement doses (200 mg per day of a standardized extract) has not produced serious adverse effects in clinical trials lasting up to four weeks. But the long-term safety picture is murkier. The European Food Safety Authority (EFSA) reviewed the evidence and concluded that the safety of tongkat ali root extract “has not been established under any condition of use,” citing concerns about potential DNA damage. That doesn’t mean it’s definitively dangerous, but it does mean the reassurance many supplement companies offer outpaces the science behind it.
What Short-Term Studies Show
Most human trials on tongkat ali have been small and brief, typically lasting four to twelve weeks with doses around 200 mg per day. In a four-week trial of 63 moderately stressed adults, a 200 mg daily dose of standardized root extract reduced cortisol levels by 16% and increased testosterone by 37% compared to placebo, with no serious adverse effects reported. Animal toxicity studies using much higher doses (up to 1,000 mg per kilogram of body weight daily for a full year) also found no treatment-related mortality or obvious organ damage.
A separate animal study testing powdered tongkat ali root at doses up to 2 grams per kilogram of body weight per day for 13 weeks found no adverse effects on body weight, blood counts, organ tissue, or kidney and liver function markers. The researchers designated that high dose as the “no observed adverse effect level.” For context, scaling that to a 150-pound human would represent a dose far exceeding what any supplement provides.
The DNA Damage Concern
The most significant red flag comes from EFSA’s 2021 safety review. When researchers tested tongkat ali extract in lab-dish studies, it caused chromosomal damage in cells, a property called clastogenicity. To follow up, they ran an in vivo test in animals at a high dose (2,000 mg per kilogram of body weight) and found DNA damage in the stomach and upper intestine, the tissues that come into direct contact with the supplement first.
Critically, the review panel determined that this DNA damage appeared to result from genuine genotoxicity rather than simple cell death. That distinction matters because genotoxic substances can, in theory, contribute to cancer development over time. An older study using the standard Ames test (a common screen for mutations) found no mutagenic activity, but the EFSA panel considered the more recent chromosomal tests more concerning. The bottom line from EFSA: the potential for DNA damage at the tissue level is a real concern, and no dose has been established as clearly safe from that standpoint.
Common Side Effects
At typical supplement doses, the side effects people report most often are insomnia, irritability, and restlessness. These align with tongkat ali’s stimulating properties and its effects on stress hormones. No reliable data exists on how frequently these side effects occur, since most clinical trials were designed to measure benefits rather than systematically track adverse reactions.
Liver Health Risks
Cases of liver injury have been reported in people taking tongkat ali, and the NIH’s LiverTox database flags this as a potential concern. Most clinical trials have excluded people with preexisting liver disease, which means the supplement hasn’t been tested in the population most vulnerable to harm. If you already have liver problems, this is a supplement with essentially no safety data for your situation. The LiverTox entry also notes that bodybuilders who develop liver injury while using tongkat ali may be simultaneously using anabolic steroids without disclosing it, which complicates the picture.
Contamination in Commercial Products
Product quality is a separate but real concern. A study testing commercial tongkat ali products found that 26% contained mercury levels between 0.53 and 2.35 parts per million, exceeding Malaysia’s safety limit of 0.5 ppm for traditional medicines. Malaysia is the primary source country for tongkat ali, so contaminated products can easily reach international markets. Because tongkat ali is sold as a dietary supplement rather than a regulated drug in most countries, there’s no mandatory testing for heavy metals before products hit shelves.
Choosing products that carry third-party testing certifications (such as NSF International or USP verification) reduces but doesn’t eliminate this risk.
Who Should Avoid It
The existing evidence points to several groups who should be especially cautious. People with liver disease have been systematically excluded from clinical trials, and reported liver injury cases appear more frequent and severe in this population. Because tongkat ali affects testosterone and cortisol levels, anyone with hormone-sensitive conditions, including certain cancers, should avoid it. Its long-term safety in humans simply hasn’t been documented, so extended daily use for months or years is essentially uncharted territory.
The gap between tongkat ali’s popularity and its safety evidence is wide. Short-term use at low doses has a limited but generally reassuring track record in small trials. But the EFSA’s genotoxicity findings, the lack of long-term human data, and the contamination issues in commercial products all represent genuine unknowns that the supplement industry’s marketing tends to gloss over.