[skadamou]

Methylene blue is actually used to treat acquired cases of a similar condition called methemeglobinemia which is when the iron in heme is oxide from Fe2+ to Fe3+ [1]. This is different from carbon monoxide poisoning which is caused by carbon monoxide binding more tightly to hemoglobin than oxygen preventing oxygen from effectively getting into your blood.

[1] https://www.uptodate.com/contents/methemoglobinemia?search=m...

[Herodotus38]

Ahh I bet that is where the confusion is. I am a physician and I have used methylene blue in severe shock and methemoglobinemia but I was a bit worried the parent comment believed it’s a valid CO treatment.

[kazinator]

Initially suspecting that since CO poisoning and methemeglobinemia are not the same, methylene blue might not work in CO cases, I did about three seconds of web searching and found a 1933 paper about an experiment (on animals) showing methylene blue to be effective in CO poisoning.