Angioedema is an area of swelling of the lower layer of skin and tissue just under the skin or mucous membranes.The swelling may occur in the face, tongue, larynx, abdomen, or arms and legs.Often it is associated with hives, which are swelling within the upper skin.Onset is typically over minutes to hours The underlying mechanism typically involves histamine or bradykinin. The version related to histamine is due to an allergic reaction to agents such as insect bites, foods, or medications. The version related to bradykinin may occur due to an inherited problem known as C1 esterase inhibitor deficiency, medications known as angiotensin-conveing enzyme inhibitors, or a lymphoproliferative disorder. Effos to protect the airway may include intubation or cricothyroidotomy. Histamine-related angioedema can be treated with antihistamines, coicosteroids, and epinephrine.In those with bradykinin-related disease a C1 esterase inhibitor, ecallantide, or icatibant may be used.Fresh frozen plasma may be used insteadIn the United States the disease affects about 100,000 people a year. The skin of the face, normally around the mouth, and the mucosa of the mouth and/or throat, as well as the tongue, swell over the period of minutes to hours. The swelling can also occur elsewhere, typically in the hands. The swelling can be itchy or painful. There may also be slightly decreased sensation in the affected areas due to compression of the nerves. Uicaria (hives) may develop simultaneously. In severe cases, stridor of the airway occurs, with gasping or wheezy inspiratory breath sounds and decreasing oxygen levels. Tracheal intubation is required in these situations to prevent respiratory arrest and risk of death. Sometimes, the cause is recent exposure to an allergen (e.g. peanuts), but more often it is either idiopathic (unknown) or only weakly correlated to allergen exposure Ref Davidson 23rd edition pg 461