Methylene blue

Methylene blue (MB) is a synthetic dye (a phenothiazine), FDA-approved (as Provayblue, 2016) to treat a blood disorder called acquired methemoglobinemia. The starting dose there is 1 mg/kg by IV, with a repeat 1 mg/kg if needed (up to 2 mg/kg total). At low concentrations, it acts as an electron 'shuttle' in your mitochondria. It accepts electrons from NADH and hands them to cytochrome c, bypassing faulty complexes I and III to keep ATP production going. In cell and rodent studies, low-dose MB has reduced mitochondrial reactive oxygen species, improved memory in old animals, and eased neurodegeneration-related pathology. The interest in MB for aging comes partly from a few small human trials of its cognitive effects, in healthy older adults or early Alzheimer's, with mixed and modest results. But no aging or longevity use is approved. The rules for low-dose oral use vary by country, and using it off-label as a longevity agent is not supported by trial evidence.

Last reviewed: June 22, 2026

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