 Acute urticaria is common and affected 12 of population. 400 patients come in department emergency of Toulouse each year and there arent many studies in literature which evaluate the glucocorticoids treatment. The standard treatment of urticaria is antihistamines H1, but glucocorticoids treatment administered orally for short course would permit to increase quickly acute urticaria uncomplicated. Clinical trial, prospective randomized double blinded of adults with acute urticaria less 24 hours duration and no take treatment urticaria before. 