Urticaria is the medical term for hives - a common skin rash which presents with itchy pink welts. The welts can vary in size, shape, and distribution. A defining characteristic is that the individual lesions are transient, appearing and resolving within a 24 hour period. So, even though an individual may suffer from hives for weeks or even months, each welt will resolve within the timeframe of a day, only for new lesions to appear in its place.

Urticaria can be classified as acute (lasting less than 6 weeks) or chronic (lasting more than 6 weeks). Acute urticaria is commonly caused by infections, foods, medications, or insect stings/bites. Chronic urticaria is mainly idiopathic, meaning the cause is unknown. In some people, certain physical stimuli such as heat, cold, exercise, sun exposure, or pressure can induce hives. Treatments include avoiding triggers and/or allergens and the use of antihistamines (either over the counter or by prescription). For severe or recalcitrant cases, oral prednisone and other immune modulating medications may be used.