Urticaria

Urticaria, also known as hives, is an outbreak of swollen, pale red bumps or plaques (wheals) on the skin that appear suddenly either as a result of the body's reaction to certain allergens or for unknown reasons.

Hives usually cause itching, but may also burn or sting. They can appear anywhere on the body, including the face, lips, tongue, throat, or ears. Hives vary in size (from a pencil eraser to a dinner plate), and may join together to form larger areas known as plaques. They can last for hours, or up to one day before fading.

Angioedema is similar to hives, but the swelling occurs beneath the skin instead of on the surface. Angioedema is characterized by deep swelling around the eyes and lips and sometimes of the genitals, hands, and feet. It generally lasts longer than hives, but the swelling usually goes away in less than 24 hours.

Rarely, angioedema of the throat, tongue, or lungs can block the airways, causing difficulty breathing. This may become life‒threatening.

The most common foods that cause hives are nuts, chocolate, fish, tomatoes, eggs, fresh berries, and milk. Fresh foods cause hives more often than cooked foods. Certain food additives and preservatives may also be to blame.

Drugs that can cause hives and angioedema include aspirin and other nonsteroidal anti‒inflammatory medications such as ibuprofen, high blood pressure drugs (ACE inhibitors), or painkillers such as codeine.

Your doctor will need to ask many questions in an attempt to find the possible cause of hives or angioedema. Since there are no specific tests for hives or the associated swelling of angioedema testing will depend on your medical history and a thorough exam by your primary care doctor or dermatologist.

Skin tests may be performed to determine the substance to which you are allergic. Routine blood tests are done to determine if a system-wide illness is present.