Desensitization for sulfasalazine-induced skin rash in a patient with ulcerative colitis

A patient with ulcerative colitis developed a sulfasalazine-induced skin allergy manifested by a urticaria rash. The patient underwent drug desensitization. The first desensitization, done according to Holdsworth's protocol, resulted in eruption with itching at a dose of 800 mg. The second desensitization, with Das's protocol, failed to reintroduce the drug because of urticarial eruptions. The third challenge, with a more gradual increase in sulfasalazine dose than that used in Holdsworth's protocol, successfully desensitized the patient. The relationship between the drug and various adverse reactions is reviewed and the desensitization to sulfasalazine is discussed.