Background: Up to 5% of patients with dermatitis who are consecutively patch tested are allergic to one or more corticosteroids. However, few reports of allergic mucosal and skin symptoms in patients with asthma and rhinitis caused by inhaled corticosteroids exist. Objective: Our purpose was to determine whether inhalation of budesonide would result in reactivation of patch test reactions caused by budesonide. Methods: The study, which was randomized, double-blind, and placebo-controlled, was ethically reviewed by the Medical Faculty, University of Lund, Sweden. Fifteen nonasthmatic patients who were initially given a diagnosis of budesonide hypersensitivity on patch testing from less than 1 up to 8 years before the study were provoked with budesonide or placebo by inhalation 6 weeks after they had been patch tested with budesonide, its R and S diastereomers, and potentially cross-reacting substances. Lung function was studied by using spirometry and repeated peak expiratory flow measurements. Results: In 4 of 7 patients who inhaled budesonide, reactivation of previously positive patch test reactions was noted within 24 hours, in contrast to 0 of 8 patients who inhaled placebo (P = .026). No adverse pulmonary responses could be detected. Conclusion: This study shows that allergic skin reactions may occur in patients with contact allergy to budesonide when inhaled forms of the drug are used. (J Am Acad Dermatol 2002;46:880-5.)