What is Methylene blue?
Methylene blue is an old blue dye that, as a medicine, is the antidote for methaemoglobinaemia (restoring the blood's ability to carry oxygen). It interacts with the mitochondrial electron transport chain and inhibits the enzyme MAO-A – the basis of its hype as a “mito booster” and nootropic.
How well studied is Methylene blue?
For acute methaemoglobinaemia its effect is well established and approved. For cognitive enhancement, anti-ageing or “mitochondrial support” there are only small, preliminary studies; no benefit for healthy people has been shown.
What side effects and risks does Methylene blue have?
Together with serotonergic drugs (SSRIs, SNRIs, MAO inhibitors) and opioids it can cause severe, even fatal serotonin syndrome (boxed warning in the US label). In G6PD deficiency it can cause haemolysis; other risks include allergy up to anaphylaxis, headache, nausea, confusion and visual disturbances. Blue-green urine is harmless but it distorts pulse-oximetry readings.
Is Methylene blue approved in Germany?
In short: yes. Approved in the EU since 2011 as Methylthioninium chloride Proveblue for intravenous treatment of methaemoglobinaemia; prescription-only. Dye- or aquarium-grade products sold as “nootropics” are not medicines and may contain impurities (e.g. heavy metals). Self-use is dangerous because of the interactions.
Sources
- EMA: Methylthioninium chloride Proveblue – EPAR
- FDA Prescribing Information PROVAYBLUE (methylene blue), 2024
Note: We deliberately do not list any doses here. For approved medicines, your doctor sets the dose; for unapproved substances there is no reliable information.