Urticaria (hives) is a vascular reaction of the skin marked by the transient appearance of smooth, slightly elevated papules or plaques (wheals) that are erythematous and that are often attended by severe pruritus. Lesions typically appear over the course of minutes, enlarge, and then disappear within hours . Surrounding erythema will blanch with pressure. Urticaria may be acute or chronic
Acute = new onset urticaria < 6 weeks
Chronic = recurrent urticaria (most days) > 6 weeks
urticaria may be the cutaneous presentation of anaphylaxis, so assessment of the respiratory and cardiovascular systems is vital!