Swelling of body tissues, particularly around the face, usually due to an allergic reaction
Angioedema is a condition in which the mucous membranes and tissues under the skin suddenly become swollen. The face and neck are usually affected.
The most common cause of angioedema is an allergic reaction to a type of food, such as seafood, nuts, or strawberries (see Food allergy). Less commonly, the condition may result from an allergic reaction to a drug (see Drug allergy), most often to an antibiotic. Angioedema may also develop after an insect bite.
Rarely, a person may inherit a tendency to develop angioedema that is unrelated to an allergy. In such cases, episodes of unexplained angioedema may begin in childhood and may be triggered by stressful events, such as an injury or a dental extraction.
It is not unusual for people to have only a single episode of angioedema, for which no cause can be determined.
Swelling usually develops within a few minutes and is often asymmetrical; for example, only one side of a lip may be affected. The main symptoms are:
Swelling of any part of the body, most commonly the face and lips.
Sudden difficulty in breathing, speaking, or swallowing due to swelling of the tongue, mouth, and airways.
In about half of all cases, an itchy rash affecting areas that are not swollen (see Urticaria).
The swelling may affect the larynx (voice box) and can be life-threatening if the airway becomes blocked. Angioedema may occur at the same time as anaphylaxis, a potentially fatal allergic reaction that requires urgent medical attention. If you develop the symptoms of angioedema or you experience difficulty in breathing, you should seek medical help immediately.
Severe angioedema requires an urgent injection with the drug epinephrine (adrenaline), followed by observation in hospital. In milder cases, a corticosteroid or an antihistamine may be given to reduce the swelling; this may take hours or days to subside.
Your doctor may carry out tests to determine the cause of the angioedema. If a food allergy is suspected, a skin prick test or blood test, and/or an exclusion diet may be used to identify the substances to which you are allergic. If you suffer from severe angioedema, your doctor may teach you how to self-inject epinephrine (see Emergency aid for anaphylaxis).
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.