It is easiest to identify drugs, foods, or plants that may cause you to have hives because the response usually occurs within an hour. Finding what triggers hives such as emotional stress or multiple allergies may take more time and require skin or other tests. The treatment your doctor recommends will depend on how serious your hives are. Avoid heat or rubbing, which releases more histamines. Take antihistamine medicine to reduce the allergic response.
Some allergic reactions are emergencies.
Once the emergency symptoms have been treated you will be instructed in medication to take for the next several hours to days to prevent the reaction from recurring. These severe allergic reactions can be life-threatening and require immediate medical treatment. The effects of hives can last from a few hours to several weeks or months. Hives will eventually clear without treatment, but taking drugs such as antihistamines or corticosteroids help the hives go away faster, treat the itch, and prevent new hive formation. Chronic urticaria last for a longer period.