DefinitionAngioedema is a swelling that is similar to hives, but the swelling is under the skin instead of on the surface. Hives are often called welts. They are a surface swelling. It is possible to have angioedema without hives.
Alternative NamesAngioneurotic edema; Welts
Causes, incidence, and risk factorsAngioedema 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 heatFoods (such as berries, shellfish, fish, nuts, eggs, and milk)Insect bitesMedicines (drug allergy), such as antibiotics (penicillin and sulfa drugs), nonsteroidal anti-inflammatory drugs (NSAIDs), and blood pressure medicines (ACE inhibitors)PollenHives 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.
SymptomsThe 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 (uticaria). They turn pale and swell if irritated. The deeper swelling of angioedema may also be painful.Other symptoms may include:Abdominal crampingBreathing difficultySwollen eyes and mouthSwollen lining of the eyes (chemosis)
Signs and testsThe health care provider will look at your skin and ask you if you have been exposed to any irritating substances. A physical exam might reveal abnormal sounds (stridor) when you breathe in if your throat is affected.The health care provider may perform blood tests or allergy testing.
TreatmentMild symptoms may not need treatment. Moderate to severe symptoms may need to be treated. Breathing difficulty is an emergency condition.People with angioedema should:Avoid any known allergen or trigger that causes their symptomsAvoid any medicines, herbs, or supplements that are not prescribed by a health care providerCool compresses or soaks can provide pain relief.Medications used to treat angioedema include:AntihistaminesAnti-inflammatory medicines (corticosteroids)Epinephrine shots (people with a history of severe symptoms can carry these with them)Inhaler medicines that help open up the airwaysRanitidine (Zantac)If the person has trouble breathing, seek immediate medical help. A severe, life-threatening airway blockage may occur if the throat swells.
Expectations (prognosis)Angioedema that does not affect the breathing may be uncomfortable, but is usually harmless and goes away in a few days.
Calling your health care providerCall your health care provider if:Angioedema does not respond to treatmentIt is severeYou have never had angioedema beforeGo to the emergency room or call the local emergency number (such as 911) if you have:Abnormal breathing sounds (stridor)Difficulty breathingFaintingWheezing
ReferencesDreskin SC. Urticaria and angioedema. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier;2011:chap 260.Wasserman SI. Approach to the person with allergic or immunologic disease. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier;2011:chap 257.