Angioedema is swelling due to leakage of fluid from local blood vessels. It may be broken down into 2 main types, that due to histamine which will respond to allergy medications and that due to other factors.
If allergic (due to an allergen such as a food or drug) or idiopathic (due to histamine but not triggered by an allergen) then antihistamines or oral steroids may be helpful. Adrenalin may be used in severe cases.
If the cause is not histamine but rather leakage of fluid due to bradykinin, then standard allergy medications will be unhelpful. This form of angioedema is seen as a complication of treatment with ACE inhibitors or in complement deficiency (C1-inhibitor deficiency). The latter form of angioedema may be inherited (Hereditary Angioedema) or acquired. Angioedema due to complement deficiency may be severe and life threatening due to swelling of the larynx causing obstruction of the upper airway. ACE-Inhibitors, a class of medications given to patients with diabetes, hypertension or heart disease, may also cause severe swelling of the tongue.