Sulfhemoglobinemia after dermal application of DMSO.

A 43-y-old Caucasian female applied 4 ounces of dimethyl sulfoxide (DMSO) to her lower abdomen for treatment of interstitial cystitis. Within 24 h she developed fatigue, cyanosis and dyspnea with mild exertion. She sought medical attention 10 d later, at which time initial laboratory tests revealed a methemoglobin level of 47%. Two doses of 1 mg methylene blue/kg i.v. were given without significant improvement in either her cyanosis or methemoglobin level. Repeat analysis the day following admission using an outside lab demonstrated a sulfhemoglobin level of 6.2% and a methemoglobin level of < 0.1%. No prior reports have associated sulfhemoglobin formation with DMSO application. Carbon monoxide-oximetry may falsely identify sulfhemoglobin as methemoglobin; sulfhemoglobinemia should be considered in cases of methemoglobinemia refractory to methylene blue therapy.