A Scientific American report says a caffeine-flush supplement sold online has no human trial and a flagged painkiller mix

What the research found

Commentary, not a clinical trial. Will McCurdy, Scientific American, 19 Oct 2026. Rutaecarpine, an alkaloid from Tetradium ruticarpum (evodia), is sold online as a supplement said to clear caffeine before sleep. The report says it has not been studied in human clinical trials. In rats it induces CYP1A2, a liver enzyme that breaks caffeine down. A separate rat pharmacokinetic paper (PMCID PMC8429912) found that 100 mg/kg of rutaecarpine, given as early as three hours before caffeine, cut oral caffeine exposure, with bioavailability down by as much as 75 percent, and raised CYP1A2 activity about threefold at three hours. That is a high laboratory dose in rats, not a human serving. Scientific American also cites a 2024 Toxics paper in mice and human cells suggesting harm when rutaecarpine is combined with acetaminophen. Bill Baldwin of Clemson University, who edited that paper, is quoted saying the combination needs care. This is not a suggestion to take the supplement, with or without coffee or a painkiller. Not medical advice.

Evidence level: Clinical trial. This is among the stronger kinds of evidence, but one study rarely settles a question.

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