Although co-trimoxazole is a major cause of fixed drug eruption, there are no reports in the literature of desensitization protocols for co-trimoxazole in such patients. We present the case of an 85-year-old woman with a fixed drug eruption to co-trimoxazole. Since she needed co-trimoxazole therapy for treatment of infection of a prosthetic hip by Staphylococcus aureus, she underwent allergy te...