Recurrent Methemoglobinemia From Over-the-Counter Medication.

A 53-year-old female with a history of rheumatoid arthritis presented with acute-on-chronic shortness of breath. She had severe lung disease secondary to chronic obstructive pulmonary disease (COPD) and recurrent pneumonia. She was found to have recurrent methemoglobinemia and presented to the hospital with refractory hypoxemia. She was given intravenous (IV) methylene blue, and transfused 2 units of packed red blood cells. Her methemoglobin levels again trended up during hospitalization and after identifying and discontinuing the offending agent, an over-the-counter (OTC) benzocaine gel, her methemoglobin level was normalized and she never had a recurrence. The severity of presentation from methemoglobinemia is increased in patients with anemia, heart disease, and pulmonary disease.