Angioedema is a term used to describe a condition in which small blood vessels leak fluid into the tissues, causing swelling. It can be part of an allergic reaction where the main trigger is release of histamine from mast cells or it can be caused by an adverse reaction to certain medications where the mechanism causing the swelling differs from the allergic cause.
Angioedema usually affects the skin with swelling occurring in the deeper tissues. The most common areas of the body involved are the face, lips, tongue, throat and genital areas. Swelling in one area usually lasts between one to three days. Occasionally, swelling of internal organs like the oesophagus, stomach, or bowel can trigger chest or stomach pains.
The more common forms of angioedema occur together with urticaria or hives and this particular form responds to treatment with medications such as antihistamines, or in an emergency, when the airway or cardiovascular systems are involved, adrenaline.