UMEM Educational Pearls

Category: Toxicology

Title: Dapsone-Induced Methemoglobinemia

Keywords: dapsone, methemoglobinemia, methylene blue (PubMed Search)

Posted: 6/27/2008 by Fermin Barrueto, MD (Updated: 2/18/2020)
Click here to contact Fermin Barrueto, MD

  •  Dapsone has been used to treat leprosy but more commonly to in brown recluse spider bites and to prevent PCP pneumonia and toxoplasmosis in our HIV population
  • It can cause methemoglobinemia: a reduced form of iron (ferrous to ferric) in the Hb molecule that decreases your oxygen carrying capacity. 
  • Due to its color, cyanosis is a predominant symptom out of proportion to symptoms.
  • Treatment: Methylene Blue 1-2 mg/kg IV
  • Pitfall: Dapsone's long half-life may cause reoccurrence of MetHb and require retreatment