Definition of Angioedema:

Angioedema is a swelling, similar to hives, but the swelling is beneath the skin rather than on the surface. The hives are called welts. It is also possible to have angioedema without hives.

See also: Hereditary angioedema

Causes, incidence, and risk factors:

Angioedema may be caused by an allergic reaction. During the reaction, histamine and other chemicals are released into the bloodstream. The body releases histamine when the immune system detects a foreign substance called an allergen.

Often the cause of angioedema is never found.

The following items may cause angioedema.

• Animal dander (scales of shed skin)
• Medications (drug allergy), such as antibiotics (penicillin and sulfa drugs) and blood pressure medicines (ACE inhibitors)
• Exposure to water, sunlight, cold or heat
• Foods (such as berries, shellfish, fish, nuts, eggs, milk, and others)
• Insect bites
• Pollen

Hives and angioedema may also occur after infections or with other illness (including autoimmune disorders such as lupus and leukemia and lymphoma).

A form of angioedema runs in families and has different triggers, complications, and treatments. This is called hereditary angioedema, and it is not discussed here.