A pediatric case of chronic idiopathic urticaria induced by antihistamines.

A previously healthy 8-year old boy was seen for a second opinion regarding a 1-year history of urticaria. The initial onset of generalized urticaria was noted 30 minutes after a dose of fexofenadine for seasonal allergy symptoms. He had tolerated fexofenadine in previous pollen seasons without any complications. Since onset, he has had daily generalized urticaria. After 2 months of symptoms despite taking daily fexofenadine (180 mg), the medication was changed to diphenhydramine 25 mg nightly. After 4 months without improvement, his medication was then changed to loratadine 5 mg twice daily, and his medication subsequently was changed to cetirizine 10 mg twice daily because symptoms remained unchanged. Although there was waxing and waning of severity, he had no days in which he was entirely symptom-free and had missed 19 days of school due to flares. Other than antihistamines, his only medication was montelukast for mild persistent asthma. Interestingly, since stopping cetirizine and montelukast for 3 days in anticipation of possible skin prick testing at the clinic, he did not have any urticaria. The patient’s urticaria occurred year-round, with no change in any particular season or time of day. His family reported that although he may have missed a day or two, he otherwise took an