Hemolysis (more likely to occur with deficiency of glucose 6-phosphate dehydrogenase or G6-PD), bone marrow aplasia, renal disease, peripheral neuropathy, methemoglobinemia, nausea, dizziness, fatigue and other systemic manifestations may occur singly or in combination in patients on dapsone therapy. This evidence concerns the gene G6PD and methemoglobinemia.