Urticaria itch. Over 25% of the population will experience an episode of acute urticaria some time during her life. Most episodes last a week or 2 in etiology in many cases is not determined. Hives lasting for longer than 6 weeks are arbitrarily classified as chronic urticaria. Patient’s with chronic urticaria are often subjected to many laboratory tests which in most cases is not helpful In determining the cause. Medications and foods are a common cause. Aspirin, nonsteroidal anti-inflammatory drugs, penicillins and sulfonamides are common causes. Insect bites can cause severe swelling that resembles a hive.


Acute urticaria. This case of hives appeared suddenly after taking a medication for hypertension. The hives cleared when the medication was stopped.

Chronic urticaria and also because by foods and medicines. There are many other possible causes. These include systemic lupus erythematosus, chronic infections and lymphoma.


Chronic urticaria. This patient has had hives for over six weeks. Hives lasting longer than this period of time are classified as chronic urticaria.

Urticaria may occur as a non-allergic phenomenon. These are classified as physical urticaria and are induced by scratching, pressure, cold, heat and sunlight. The most common physical urticaria is induced by rubbing or scratching and is called dermographism (skin writing).


Dermagraphism are hives produced by scratching



Dermagraphism. Scratching has produced linear welts.


Dermagraphism. This child has a severe case. Scratching results in thick welts in about three minutes. These hives may last for a few minutes to a few hours and then disappear.