Hives are a type of rash affecting the outermost layers of the skin, and are typically caused by contact with a skin irritant or as a reaction to an allergen. In some cases, hives will break out when a patient has reacts badly to systemic medications. They typically resolve within six weeks or less, but if they do not, the condition is classified as chronic urticaria. Chronic cases of hives are not usually the result of contact with allergens. Antihistamines can bring outbreaks under control if the hives are the result of an allergic reaction, and soothing ointments and topical creams may also be applied to the skin to ease itching, pain and swelling.