Peter Attia· MD
there are two problems one you have different purities so you have at least three categories of purities for methylene blue the one that should be used by in humans like in them they for in emergency room it is called pharmaceutical quality or the US we call USP grade the Europeans have a similar but the one day the USP is actually more restraint than the European medium blue then there is chemical quality that is using laboratory for staining but that can go over for example the one produced by Sigma as about 15 percent impurities it should not be given to live animals or humans and is readily available so I always one warn against that