Physical urticaria (PU) is a subgroup of acquired, chronic inducible urticaria which is associated with a known physical trigger. In PU, the symptoms are induced by exogenous physical triggers, such as friction, pressure, vibration, cold, heat, or solar radiation. All the PUs may manifest with both wheals and angioedema at the sites of the triggers with the exceptions that urticaria factitia (UF) (symptomatic dermatographism) presents with wheals only and pressure urticaria presents with angioedema only. More than one form of physically induced urticarias can be present in one patient
