Michael Davis, MD, pediatrician, discusses hives or urticaria rashes in children. Hives can be an allergic response to food allergy, medication allergy, or insect allergies. Sometimes a viral infection, or exposure to sun or cold can cause hives. Hives are usually very itchy. Hives usually resolve on their own, but can be related to a more worrisome problem, such as anaphylaxis, which can be life threatening.