What should you know about acute hives?

Acute hives are sudden, itchy, raised welts that usually fade individually while new ones may appear elsewhere. They can follow an infection, medicine, food, insect sting, heat, cold, pressure, or another trigger, although the cause is not always clear. Most episodes settle, but swelling involving the mouth or airway requires emergency help.

Hives, also called urticaria, develop when skin cells release chemicals that allow fluid to collect in the surface layers of skin. The welts may be small or join into larger patches, and they can change shape or location. They often itch, sting, or feel warm. A mark that stays fixed, becomes bruised, blisters, or is painful rather than itchy deserves medical assessment because it may have another cause.

Use a cool compress, wear loose clothing, and avoid hot showers or vigorous scratching. Note recent medicines, foods, illnesses, bites, exercise, temperature exposure, and skin pressure; photographs can show how the rash changes before an appointment. An oral antihistamine may reduce itching and welts when it is suitable for you. Follow the product directions or a clinician's instructions, and check before use if you are pregnant, breastfeeding, treating a child, or taking medicines that cause drowsiness. Do not stop a prescribed medicine without medical advice unless emergency services direct you.

Call emergency services immediately for trouble breathing, throat tightness, wheezing, faintness, confusion, or swelling of the tongue or inside the mouth. These signs can accompany a severe allergic reaction and should not be watched at home. Arrange prompt medical assessment if facial swelling develops, the rash is widespread or repeatedly returns, symptoms remain troublesome despite appropriate antihistamine use, or you suspect a medicine triggered the episode.

Ask whether the appearance and movement of the welts fit hives, whether any recent medicine needs review, and which antihistamine is appropriate with your health conditions and current treatments. If episodes recur, discuss whether a trigger diary would help and what symptoms should change your action plan. Oral corticosteroids are reserved for selected situations and require clinician guidance because their risks and benefits vary by person.