Benefit of ketotifen in patients with eosinophilic gastroenteritis. PURPOSE: Eosinophilic gastroenteritis (EG) is a rare condition of unknown etiology characterized by vomiting, diarrhea, protein-losing enteropathy, and eosinophilic infiltration of the gastrointestinal mucosa. The potential association of EG with allergy and related mast-cell release of mediators led us to evaluate the ability of an antihistamine drug to modify the course of the disease. PATIENTS AND METHODS: Six patients with protracted gastrointestinal symptoms were diagnosed with EG because of histologic evidence of predominantly eosinophilic infiltrates in the gastrointestinal mucosa. Each patient was treated in an open trial for 12 months with ketotifen (Zaditen), an antihistamine of the H1 class that is known to stabilize mast cells. RESULTS: All six patients improved clinically; four also gained weight. Total serum IgE levels decreased after 4 to 6 months of therapy. Clearing of eosinophilic infiltrates was documented in the four patients who underwent follow-up mucosal biopsies. CONCLUSION: We conclude that ketotifen treatment represents a safe and effective alternative to traditional systemic corticosteroid therapy for treatment of EG. 