Acute allergic angioedema is an acute, but temporary, swelling of the skin caused by an allergic reaction. Skin and mucus membranes of the lips and around the eyes are affected most often, but swelling can may occur in the lining of the throat and mouth.
This allergen-triggered form of angioedema is almost always accompanied by hives and other signs of an allergic reaction. It occurs relatively quickly, with swellings peaking in size one to two hours after exposure to an allergen — a substance seen as a potential threat by the body’s immune system.
Acute allergic angioedema can be triggered by a wide range of allergens. Common triggers include foods, such as nuts, shellfish, milk, and eggs, as well as insect stings or bites.
Some medicines also can trigger this type of angioedema, including penicillin, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen, certain antibiotics, and anti-inflammatory medications. Some vaccines can trigger the condition, as may certain agents given to patients to improve the contrast and readability of certain types of medical imaging tests like iodine and barium.
Swelling typically occurs shortly after exposure to an allergen, and can be triggered by the same allergen again at a later date.
The severity of acute allergic angioedema varies depending on the location and speed of the swelling.
Anaphylactic shock, which is a sudden drop in blood pressure and constriction of the throat due to a severe allergic reaction, is of major concern in this form of angioedema. Emergency treatment is essential. Anaphylaxis usually occurs quickly — within seconds or minutes of exposure to an allergen — and is caused by the immune system releasing a flood of chemicals that cause blood pressure to drop, rapid swelling to the mouth, throat, and neck. Also, airways become narrower, which makes breathing difficult.
Other symptoms of anaphylactic shock may include hives or flush, very pale skin, a weak and rapid pulse, dizziness, fainting, or collapse.
More often, however, cases of acute allergic angioedema are mild and localized to limited areas, such as the lips or eyes, and are not life-threatening. Swellings can be painful and tender, but may not be itchy.
Swellings associated with acute allergic angioedema generally do not last more than 48–72 hours (two to three days.) In the early hours of the reaction, when there is the highest risk for swelling to become problematic or life-threatening, acute allergic angioedema can be treated with allergy medications, such as antihistamines, corticosteroids and, in severe cases, epinephrine.
Cases of anaphylaxis, when a person is in shock or going into shock, require emergency medical attention.
Last updated: Dec. 10, 2021
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