HBG2 and methemoglobinemia: Glutathione, nicotinamide adenine dinucleotide with hydrogen (NADH), vitamin C, vitamin E, and methylene blue were all used to decrease methemoglobin levels [101,102,103], along with the occasional use of cimetidine to lower methemoglobin in those with a history of significant methemoglobinemia [96,104], while high-dose folic acid (folinic acid, i.e., leucovorin and L-methyl-folate) was prescribed to minimize anemia from the inhibition of bacterial synthesis of dihydrofolic acid by dapsone [105].