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. In most cases, the cause of angioedema is never found.
The following may cause angioedema:
- Animal dander (scales of shed skin)
- Exposure to water, sunlight, cold or heat
- Foods (such as berries, shellfish, fish, nuts, eggs, and milk)
- Insect bites
- Medicines (drug allergy), such as antibiotics (penicillin and sulfa drugs)
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Blood pressure medicines (ACE inhibitors)
Hives and angioedema may also occur after infections or with other illnesses (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 in this article.
The main symptom is sudden swelling below the skin surface. You may also develop welts or swelling on the surface of your skin. The swelling usually occurs around the eyes and lips. It may also be found on the hands, feet, and throat. The swelling may form a line or be more spread out. The welts are painful and may be itchy. This is known as hives (urticaria). They turn pale and swell if irritated. The deeper swelling of angioedema may also be painful.
Other symptoms may include:
- Abdominal cramping
- Breathing difficulty
- Swollen eyes and mouth
- Swollen lining of the eyes (chemosis)