Provayblue

Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication.[4] Methylene blue is a thiazine dye.[4] It works by converting the ferric iron in hemoglobin to ferrous iron.[2] As a medication, it is mainly used to treat methemoglobinemia.[4][2] Specifically, it is used to treat methemoglobin levels that are greater than 30% or in which there are symptoms despite oxygen ther... [wikipedia]