TABLE 1.

Classification of urticaria

Type	Duration	Characteristic features
Acute urticaria	Less than 6 weeks
Chronic spontaneous urticaria	More than 6 weeks	Recurs at least 2 times a week.
Chronic inducible urticarial (Chronic physical urticaria)	More than 6 weeks	Subtypes of urticaria according to triggering factors • Dermatographic urticaria • Cold urticaria • Heat urticaria • Delayed pressure urticaria • Solar urticaria • Vibration urticaria • Aquagenic urticaria • Contact urticaria • Cholinergic urticaria
Episodic chronic urticaria	Lasts more than 6 weeks	Recurs at least 2 times a week.