Supplement · Grade B/C

Tongkat Ali and medications.

Every documented pair, every citation. Below: 3 documented pairs grouped by mechanism.

Tongkat Ali is in the Distil supplement database, evidence Grade B/C. The page below lists every medication we have explicitly assessed it against.

Tongkat Ali, also called Eurycoma longifolia or longjack, is taken at 200 to 400mg a day of standardised extract, with the Physta brand carrying the best evidence. It is used for testosterone support, libido, cortisol reduction and stress, but the honest framing matters: the Grade B to C evidence is mostly in men with low-normal or stress-suppressed testosterone, not healthy men with normal levels, and the effect size is modest. Trials show normalised testosterone in hypogonadal men and reduced cortisol with higher testosterone in stressed subjects. Two practical cautions stand out. Unregulated products have been found contaminated with heavy metals, so a certified brand is important. There is also a single 2025 case report of new-onset atrial flutter in an older man after starting it, so anyone with arrhythmia, palpitations or unexplained dizziness should avoid it pending more evidence and flag any heart symptoms to a GP. It may also interact with immunosuppressants. Worthwhile only with realistic expectations and a trusted source.

Below are the 3 documented pairs we have explicitly assessed for Tongkat Ali: 3 amber. The pairs cluster around 2 mechanisms: Additive androgenic effect and Androgen-raising vs androgen-lowering (opposing). Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.

Documented interactions

Additive androgenic effect

Amber Testosterone

Tongkat ali can modestly raise the body's own testosterone, so taking it alongside prescribed testosterone may add to that effect. If you are on testosterone replacement, mention this supplement to the prescriber who monitors your levels before combining them.

PMID 33559971 · PMID 37697053 · BNF: Testosterone

Reviewer-flagged: awaiting clinical-reviewer sign-off.

Androgen-raising vs androgen-lowering (opposing)

Amber Dutasteride

Dutasteride works by lowering a potent form of testosterone. Tongkat ali tends to raise the body's testosterone, so in theory it could work against what dutasteride is doing. If you take dutasteride for prostate symptoms, it is worth discussing this supplement with your prescriber.

PMID 33559971 · PMID 37697053 · BNF: Dutasteride

Reviewer-flagged: awaiting clinical-reviewer sign-off.

Amber Finasteride

Finasteride works by lowering a potent form of testosterone. Tongkat ali tends to raise the body's testosterone, so in theory it could work against what finasteride is doing. If you take finasteride for hair loss or prostate symptoms, it is worth discussing this supplement with your prescriber.

PMID 33559971 · PMID 37697053 · BNF: Finasteride

Reviewer-flagged: awaiting clinical-reviewer sign-off.

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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