Acute urticaria can be treated with anti-histamines (anti-allergic drugs) for 14-21 days, and, in some cases, with systemic corticosteroids for a short period of time (not exceeding 7 days)

At the ER environment, if a patient is admitted with severe urticaria and/or angioedema symptoms, injectable anti-histamines and corticosteroids are administered. If, additionally to urticaria and angioedema symptoms, other symptoms including hoarseness, shortness of breath, nausea/ vomiting, dizziness, or unconsciousness are found, adrenaline can be administered subcutaneously.

Patients prone to severe allergic urticaria and angioedema and/ or anaphylaxis are advised to carry a pre-filled self-applicable adrenaline syringe with them and use it, whenever necessary, until medical care is provided. Your doctor will prescribe this if it fits to your case.

J Allergy Clin Immunol. 2014 May;133(5):1270-7
Immunol Allergy Clin North Am. 2014 Feb;34(1):11-21