Angioedema is swelling that develops under the skin and in the tissues that line some organs. Painful swelling can develop on the face and in other parts of the body. Swelling in the belly may cause pain, nausea, vomiting, and diarrhea.

Angioedema may appear as a reaction to a substance (allergen). Allergens include medicines, foods, insect bites, animal dander, and pollen. Angioedema also may appear during changes in temperature or emotional stress, or after an infection or illness. It can also run in families.

Most cases of angioedema will go away within a few days without treatment. However, swelling in the throat can interfere with breathing and may be life-threatening. Angioedema also may be a sign of a more serious allergic reaction (anaphylaxis) that requires emergency care. Since angioedema can get worse quickly, a person with this condition should be evaluated by a doctor.