Merck Manual

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James Fernandez

, MD, PhD, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University

Reviewed/Revised Oct 2022 | Modified Nov 2023
Topic Resources

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 other 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, digestive tract, 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 Hives Hives are red, itchy, slightly elevated swellings. The swelling is caused by the release of chemicals (such as histamine) from mast cells in the skin, which cause fluid to leak out of small... read more Hives , which are small, red, itchy, slightly elevated areas of swelling, often with a pale center. Both hives and angioedema involve swelling, but in angioedema, the swelling is deeper (under the skin) than it is with hives, and it may not itch.

There are rare hereditary or acquired forms of angioedema Hereditary and Acquired Angioedema Hereditary angioedema (a genetic disorder) and acquired angioedema (acquired C1 inhibitor deficiency) are caused by a deficiency or malfunction of C1 inhibitor, which is part of the immune system... read more Hereditary and Acquired Angioedema . These forms are caused by a deficiency or malfunction of a substance called C1 inhibitor, which is part of the immune system. Hereditary angioedema and acquired angioedema resemble angioedema caused by an allergic reaction. However, hives do not develop, and the cause is different.

Angioedema may be acute or chronic.

Acute angioedema

Acute angioedema develops suddenly after exposure to a trigger.

Common triggers are

Angioedema without hives is sometimes caused by ACE inhibitors, which are used to treat high blood pressure and heart failure. When ACE inhibitors are the cause, the face and upper airways are most commonly affected, but the intestine may be affected.

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.

Chronic angioedema

Angioedema can be chronic, recurring over weeks or months. The cause is usually unknown, but it may be repeated, 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 or acquired angioedema.

However, usually when angioedema without hives recurs, no specific cause is identified—called idiopathic angioedema.

Symptoms of Angioedema

In angioedema, swelling may not be equal on both sides of the body, and it can be mildly painful. It can affect the back of the hands or feet, eyelids, tongue, face, 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 Hives are red, itchy, slightly elevated swellings. The swelling is caused by the release of chemicals (such as histamine) from mast cells in the skin, which cause fluid to leak out of small... read more 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.

Images of Angioedema

Diagnosis of Angioedema

  • A doctor's evaluation

People should see a doctor immediately if they develop angioedema.

The cause of angioedema 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 or if family members have angioedema, doctors may do tests for hereditary or acquired forms of angioedema Diagnosis Hereditary angioedema (a genetic disorder) and acquired angioedema (acquired C1 inhibitor deficiency) are caused by a deficiency or malfunction of C1 inhibitor, which is part of the immune system... read more Diagnosis .

Treatment of Angioedema

  • Antihistamines

  • Corticosteroids

  • Sometimes fresh frozen plasma, ecallantide, or purified C1 inhibitor

  • Sometimes epinephrine

If the cause of angioedema is obvious, people should avoid it if possible. If the cause is an insect sting, doctors may prescribe a self-injector of epinephrine that people can use if an insect stings them again.

If the cause of angioedema is not obvious, all nonessential drugs should be stopped until symptoms resolve.

For mild angioedema with hives, taking antihistamines partially relieves the itching and reduces the swelling. Corticosteroids Corticosteroids: Uses and Side Effects Corticosteroids: Uses and Side Effects , 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. 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, corticosteroids, and epinephrine may not help. If the cause is an ACE inhibitor, symptoms usually resolve about 24 to 48 hours after stopping the drug. If symptoms do not resolve, are severe, or are getting worse, doctors sometimes give fresh frozen plasma Plasma People are sometimes given transfusions of whole blood during severe bleeding (for example after an injury or pregnancy complications), but usually they are given only the blood component they... read more Plasma or certain drugs such as ecallantide. Purified C1 inhibitor derived from human blood can also be used.

For idiopathic angioedema, a high dose of an antihistamine, taken by mouth, may help.

Emergency treatment

If severe angioedema results in difficulty swallowing or breathing or in collapse, prompt emergency treatment is necessary. Doctors must then open the person's airway by doing one or both of the following:

  • Injecting epinephrine under the skin or into a muscle (to reduce the swelling)

  • Inserting a breathing tube through the person’s mouth or nose and into the windpipe (intubation)

If the airway closes too fast, doctors may have to make a small incision in the skin over the windpipe and insert a breathing tube.

People who have severe reactions should always carry a self-injecting syringe of epinephrine to be used immediately if a reaction occurs. Antihistamine pills may also help, but epinephrine should be injected before taking antihistamine pills.

After a severe allergic reaction, such people should go to the hospital emergency department, where they can be checked and treated as needed.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Anacin Adult Low Strength, Aspergum, Aspir-Low, Aspirtab , Aspir-Trin , Bayer Advanced Aspirin, Bayer Aspirin, Bayer Aspirin Extra Strength, Bayer Aspirin Plus, Bayer Aspirin Regimen, Bayer Children's Aspirin, Bayer Extra Strength, Bayer Extra Strength Plus, Bayer Genuine Aspirin, Bayer Low Dose Aspirin Regimen, Bayer Womens Aspirin , BeneHealth Aspirin, Bufferin, Bufferin Extra Strength, Bufferin Low Dose, DURLAZA, Easprin , Ecotrin, Ecotrin Low Strength, Genacote, Halfprin, MiniPrin, St. Joseph Adult Low Strength, St. Joseph Aspirin, VAZALORE, Zero Order Release Aspirin, ZORprin
ARYMO ER, Astramorph PF, Avinza, DepoDur, Duramorph PF, Infumorph, Kadian, MITIGO, MORPHABOND, MS Contin, MSIR, Opium Tincture, Oramorph SR, RMS, Roxanol, Roxanol-T
No brand name available
Adrenaclick, Adrenalin, Auvi-Q, Epifrin, EpiPen, Epipen Jr , Primatene Mist, SYMJEPI, Twinject
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