Recurrent myalgias associated with cimetidine

A chronically hemodialyzed patient experienced recurrent episodes of myalgia while on cimetidine treatment (400 mg/day). After two uneventful courses of cimetidine, the pain appeared at the end of a third fourteen-weeks long course. Severe myalgia occurred at the sixth week of a fourth exposure to cimetidine. Pain was predominant in the hip area, disappeared within a few days after withdrawal and recurred three weeks after resuming therapy. There was no sign of neurological involvement and CPK remained consistently normal. Ranitidine was subsequently administered for four months whereby the patient showed no symptoms of myalgia. This observation suggests that, in susceptible individuals, a progressive decrease in tolerance to cimetidine might occur with repeated courses.