Angioedema and urticaria (hives) are both allergic reactions that involve the skin characterized by edema. In the former however, deeper layers of the skin is involved resulting into diffuse swelling. Its old term, angioneurotic edema was coined due to the previous belief that the condition affects the brain.

Mechanism of the allergic reaction

Common allergens like pet dander, food, pollen, and medications are closely attributed to the appearance of angioedema. ACE inhibitors, a class of drug used in the treatment of hypertension, is said to be the primary cause of drug-induced angioedema. The condition may also be inherited.  The allergic reaction commences as allergens invade the body and sets off antibodies (immunoglobulin E) that activate mast cells to release chemicals that lead to the appearance of edema within 1-2 hours upon exposure to the offending agent.

Bradykinin, one of the chemicals, is responsible for vasodilation and increased permeability of the blood vessels that leads to edema. It also stimulates nerve fibers and produces pain.

Areas that are most often affected by the swelling are the eyelids, lips, tongue, cheeks, hands, and feet. But unlike ordinary edema, the skin over the reaction does not pit on pressure. If the feet are affected, walking will be impaired. Mucous linings of the nose, upper airways, and digestive tract would elicit painful and life-threatening consequences. Typically, attacks usually last 24 to 36 hours. On some occasions, the swelling may recur every 3 to 4 weeks. If the sequence continues for longer than 6 weeks, the condition is now called chronic urticaria,

What you doctor can do for you

Angioedema is often a complication of anaphylaxis. Oftentimes, diagnosis is based on the appearance of symptoms. On some occasions, the person might undergo skin testing for allergies. Other tests like skin biopsy and blood tests are needed for cases of angioedema with unclear causes. Antihistamines are the primary medication for edema. Epinephrine must be readily available in cases of laryngeal obstruction. Corticosteroids are used to decrease the inflammation.

What you can do

Severe angioedema requires immediate management. Call 911 immediately. Shortness of breath and wheezing/ abnormal breathing sounds are signs of airway obstruction. Mild cases are often manageable at home with medication. To prevent future attacks, avoid the allergen as much as possible.