Definition:

It is an intense itching disorder marked by formation of wheals.

Causes:

(A) General—(l) Allergy — food, drugs, parasites, inhalants etc. (2) Focal sepsis—otitis media, dental sepsis, sinusitis etc. (3) Psychogenic stress. (4) Physical agents—cold, trauma, stings, hot etc. (5) hereditary factors.

(B) Local—(1) Bites as of nettles, caterpillars, bed-bug etc.. (2) Injection of A.T.S., or penicillin etc.

(C) Idiopathic (unknown)

Types :

(1) Physical urticaria—develops after physical pressure or irritation. (2) Chronic—when urticaria persists for more than 6 weeks. (3) Solar—occurs after exposure to s n during summer months. (4) Cold—develops in association with cold wind or cold food or drinks. (5) Aquagenic— occurs in contact with water. (7) Cholinergic— after exercise, hot bathe emotional changes etc.

Signs and Symptoms

The lesions are characteristic wheals which may be red, pink or white depending upon the extent of oedema. The wheals may coalesce to form huge wheals of the size of a palm or even larger. The eruption is invariably accompanied by intense itching a sense of a burning. The wheels do not last long and disappear usually in a few hours. However new wheals may form and the process continues for long, sometimes for years.