To compare therapeutic effect of Glycyrrhizic Acid and H1-receptor antagonist for acute urticaria : a multicenter, prospective, single-blind, randomized controlled trial

INTERVENTION: Intravenous H1‐receptor antagonist (Chlorpheniramine Maleate) Glycyrrhizic Acid injestion CONDITION: acute urticaria PRIMARY OUTCOME: A visual analog scale (VAS) for pruritus as a patient's subjective measurement SECONDARY OUTCOME: Evaluation of the itch based on a new rating scale (a 'itch score'), a final global improvement rating INCLUSION CRITERIA: Patients who are newly diagnosed as an acute moderate or severe urticaria (defined by Japanese guideline); who has had no acute urticaria in 1 month before entry; and no condition requiring emergency management.