The most common site for urticaria is the trunk, though lesions may occur on any part of the body. It occurs with higher incidence in atopic individuals. Attacks persist for 6 weeks or more. Patients usually are not atopic. The course is more benign and may involve waxing and waning.
Wheals tend to be smaller, with only a few appearing at any given time.
Types of Urticaria Idiopathic. Largest category, comprising a third of acute and two thirds of chronic cases of urticaria. Usually an identifiable cause can be found. A reaction to firm stroking of the skin that occurs within 1 to 3 minutes and lasts 5 to 10 minutes. It is not true urticaria though it may be severe enough to seek medical help.