Angioedema is a medical condition that causes the skin or mucous membranes to swell and become firm. It usually happens without warning, but it sometimes occurs hours or days after an allergic reaction. This condition usually affects both eyes and lips. If the swelling involves the lower face, it can make it difficult to breathe.

Angioedema comes in two forms: hereditary and acquired. Hereditary angioedema (HAE) is a rare genetic condition. In HAE, the body's immune system causes dysfunction of the substance that coats cells and lines blood vessels. HAE is characterized by episodes of lip, tongue, hand, and foot swelling. The circulating antibodies that cause the swelling can affect other parts of the body, causing vomiting, diarrhea, joint pain, and irritable bowel syndrome. HAE can be a severe condition and may require emergency treatment.

Acquired angioedema is caused by a disturbance in the brain's nervous system that results in abnormal fluid production. It typically occurs after an infection, surgery, pregnancy, or cancer treatment. It usually affects only one part of the body at a time and is often treated quickly with drugs that inhibit fluid flow.

Idiopathic forms of this condition occur when the cause of the swelling is unknown. It is associated with other medical conditions such as diabetes, thyroid problems, and lupus but does not seem to be related to food allergies.

If your family has a history of this condition, you have a higher chance of developing it. Women are significantly more likely to develop the disease than men. The reason for this difference is not known. It is more likely to occur as a person ages, and doctors believe this is due to weakened vessels. It affects all races, but the disease seems more common in people from certain geographical areas, such as Australia and the United Kingdom.

The disease is most commonly caused by drugs that trigger allergic reactions, such as penicillin and cephalosporin antibiotics. Insect bites and other stings can also cause it. Other potential triggers include foods, animal dander, cosmetics, or ultraviolet light. There is no definitive proof that food allergies cause the disease, but research has shown that foods are responsible for the condition in some people.

Mild symptoms might not require treatment. People with severe symptoms usually get treatment in the hospital by receiving a drug called a histamine-2 receptor antagonist. Histamine-2 receptor antagonists are anti-inflammatory drugs that can rapidly halt swelling. They are given intravenously or by injection. Symptoms usually dissipate within a few hours. The usual course of treatment is to take medication regularly for six to eight weeks. If a family member has this condition, consider speaking to your doctor about genetic testing.