The dermatologist may also recommend using a food diary and a trial elimination diet. They are then added back to the diet, one at a time, to see if the hives reappear. If the hives do recur, the cause of the urticaria has been identified and can be avoided in the future. In cases of acute urticaria, your dermatologist will try to identify the cause of the hives and eliminate it. If necessary, he or she may prescribe a mild antihistamine.
Antihistamines stop the release of histamine from mast cells.
This medication is taken just once a day. Because the hives of chronic urticaria disappear after 12 to 24 hours, and may reappear somewhere else, it is important that the antihistamine be taken regularly, as prescribed by the dermatologist, even if your hives have not reappeared. However, drowsiness may occur at more than the recommended dose. The most common side effects occurred about as often as they did with a sugar pill, including headache, drowsiness, fatigue, and dry mouth. At the recommended dose, it won't make kids drowsy or cause hyperactivity.