Methemoglobinemia is a disorder of the blood where the hemoglobin produced is abnormal. The hemoglobin's ability to deliver oxygen effectively to the tissues is impaired. The likely causes are exposure to drugs like nitrates or anesthetics and genetic inheritance. Discoloration of the skin, fatigue, headache, lethargy and seizures are symptoms of this disorder. Methylene blue medication and exchange transfusions are used to treat the disorder.