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. Opiates may act directly on mast cells to cause histamine release.
Angiotensin converting enzyme inhibitors are a common cause of drug induced angioedema.
Papular urticaria Idiopathic C. Clinical Features Index Urticaria consists of raised, erythematous skin lesions that are itchy, tend to be evanescent in any one location, and generally are worsened by scratching. Angio-oedema is a reaction similar to urticaria except that it occurs in deeper tissue and is characterised by asymmetrical swelling of tissue. Pruritus, however, is uncommon with angio-oedema which more typically has a burning sensation. Any area of the body may be involved, although the perioral and periorbital regions, tongue, genitalia and extremities are involved most frequently. Laryngeal oedema is the most serious manifestation of angio-oedema.