<unk>  is a distinct subgroup of the urticaria that are induced by an exogenous<unk>  stimulus rather than occurring spontaneously. There are seven subcategories that are recognized as independent diseases.<unk>  is known to be painful, itchy and<unk> ly unappealing; it can recur for months to years of a person's life.
Physical urticaria
Cold urticaria
Pressure urticaria
Solar urticaria
Cholinergic urticaria
Delayed pressure urticaria
Heat urticaria
Dermatographic urticaria