Causes
This can be caused by taking medications that contain sulfonamides under certain conditions (i.e. overdosing of sumatriptan).
Sulfhemoglobinemia is usually drug induced. Drugs associated with sulfhemoglobinemia include acetanilid, phenacetin, nitrates, trinitrotoluene and sulfur compounds (mainly sulphonamides, sulfasalazine). Another possible cause is occupational exposure to sulfur compounds.
It can be caused by phenazopyridine.
Read more about this topic: Sulfhemoglobinemia