Angioedema is swelling of areas of tissue under the skin, sometimes affecting the face and throat.

• Angioedema can be a reaction to a drug or substance (trigger), a hereditary disorder, a rare complication of cancer, or an immune disorder, but sometimes the cause is not known.
• Angioedema may involve swelling in the face, throat, and airways.
• Antihistamines can relieve mild symptoms, but if angioedema makes swallowing or breathing difficult, prompt emergency treatment is needed.

Angioedema often occurs with hives . Both hives and angioedema involve swelling, but in angioedema, the swelling is deeper (under the skin) than it is with hives.

Common triggers are

• Many drugs, such as aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs—see Pain: Nonsteroidal Anti-Inflammatory Drugs), and certain opioids (called opiates) such as morphine and codeine
• Insect stings or bites
• Allergy injections (allergen immunotherapy)
• Certain foods—particularly eggs, fish, shellfish, nuts, and fruits

Eating even a tiny amount of some foods can suddenly result in angioedema. But with other foods (such as strawberries), these reactions occur only after a large amount is eaten.

Also, angioedema sometimes occurs after a dye that can be seen on x-rays (radiopaque dye) is used during an imaging test. Angioedema without hives is sometimes caused by angiotensin-converting enzyme (ACE) inhibitors, which are used to treat hypertension and heart failure.

Angioedema can be chronic, recurring over weeks or months. The cause may be habitual, unintentional intake of a substance, such as penicillin in milk or a preservative or dye in foods. Use of certain drugs, such as aspirin, other NSAIDs, or opioids, can also cause chronic angioedema. Chronic angioedema that occurs without hives may be hereditary angioedema (see Allergic Reactions and Other Hypersensitivity Disorders: Hereditary and Acquired Angioedema). However, usually when angioedema recurs (with or without hives), no specific cause is identified—called idiopathic angioedema.

Symptoms

Angioedema may affect part or all of the hands, feet, eyelids, tongue, lips, or genitals. Sometimes the membranes lining the mouth, throat, and airways swell, making swallowing or breathing difficult. Occasionally, the digestive tract is involved, resulting in nausea, vomiting, crampy abdominal pain, or diarrhea.

Many people also have hives. Hives usually begin with itching. Typically, crops of hives then come and go. One spot may remain for several hours, then disappear, and later, another may appear elsewhere. After the hive disappears, the skin usually looks completely normal.

Diagnosis

The cause is often obvious, and tests are seldom needed because the reactions usually resolve and do not recur. If angioedema recurs and the cause is not clear, doctors ask people about all the drugs they are taking and all food and drink they are consuming. If the cause is still not clear, particularly if people have no hives, doctors may do tests for hereditary forms of angioedema (see Allergic Reactions and Other Hypersensitivity Disorders: Hereditary and Acquired Angioedema).

If the cause is a bee sting, people should see a doctor. Then they can obtain advice about treatment if another bee sting occurs.

Treatment

If the cause is obvious, people should avoid it if possible. If the cause is not obvious, people should stop taking all nonessential drugs until symptoms resolve.

For mild angioedema with hives, taking antihistamines partially relieves the itching and reduces the swelling. Corticosteroids, taken by mouth, are prescribed for severe symptoms when other treatments are ineffective, and they are given for as short a time as possible. When taken by mouth for more than 3 to 4 weeks, they have many, sometimes serious side effects (see Joint Disorders: Corticosteroids: Uses and Side Effects). Corticosteroid skin preparations (such as creams, ointments, and lotions) do not help. For angioedema without hives (as when caused by an ACE inhibitor or a hereditary form of angioedema), antihistamines and corticosteroids may not help. In such cases, doctors sometimes give fresh frozen plasma or a drug called a C1 inhibitor.

If severe angioedema results in difficulty swallowing or breathing or in collapse, prompt emergency treatment is necessary. Most people who have these reactions should always carry a self-injecting syringe of epinephrine and antihistamine pills to be used immediately if a reaction occurs. After a severe allergic reaction, such people should go to the hospital emergency department, where they can be checked and treated as needed.

Last full review/revision August 2012 by Peter J. Delves, PhD