Angioedema is frequently associated with urticaria but the two may occur independently.
Chronic urticaria occurs more frequently in mid-life, especially in women.
A clinical classification is given in Table 1. Therefore, most chronic urticaria is idiopathic. In acute urticaria the chances of determining the cause are higher. Acute urticaria and angiooedema may also be caused by allergen exposure including insect stings or food or drug ingestion. Some of the more common drugs include penicillin, cephalosporins and sulphonamides.