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Angioedema is a pathologic condition first descrive by Quincke and Osler. It can be genetically determined or acquired, and it is caused by a vascular reaction induced by deficiency or functional alteration of the C1 inhibitor (C1-INH), an enzyme involved in the regulation of complement, contact, fibrinolytic, and coagulation systems. Two forms of angioedema have been described in the literature: hereditary angioedema (HAE) and acquired or idiopathic angioedema (AAE). HAE is characterized by dominant autosomal transmission, early onset, and a positive family history. It is caused by a mutation of the gene for C1-INH, localized on chromosome 11. Type 1 HAE is the most frequent form (85% of cases) and is associated with deficiency of functional C1-INH in plasma (10%-30% of normal values). Type 2 HAE is characterized by normal or elevated plasma levels of dysfunctional C1- INH.8 Type 3 HAE occurs mainly in women. Affected persons display the typical clinical features of C1-INH deficiency but have normal plasma levels and functionality of C1-INH. Mutations in the coagulation factor XII gene have been detected in some of these patients. AAE is characterized by late onset, usually after the fourth decade, and is not associated with a positive family history.6 Type 1 AAE is caused by increate catabolism of C1-INH and is generally associated with a positive history of benign or malignant lymphoproliferative disorders. Type 2 AAE is associated with autoantibodies against C1-INH. Deficiency or dysfunction of C1-INH can cause a deregulation of the fibrinolytic system, of the complement pathway, of the contact system, and of the coagulation cascade, resulting in release of vasoactive substances, an increase in vessel permeability, and development of diffuse edemas. Hereditary and acquired forms of angioedema are clinically indistinguishable. Edemas develop gradually over a period of 12 to 36 hours and require 2 to 5 days to subside completely. The frequency and severity of edema attacks vary from patient to patient and even in the same individual. This variability can change significantly over a patient’s lifetime: symptoms may intensify dramatically after puberty, although some cases have been reported that had been asymptomatic until the second decade of life and later. The diagnosis of angioedema can often be suspected from a positive family history associated with the typical symptoms. Nevertheless, the diagnosis needs to be confirmed by laboratory tests to assess the quantity and function of C1-INH. The differential diagnosis of angioedema includes anaphylactic shock. Considering the potential risk of asphyxia, it is essential to obtain an accurate patient history to ensure that the most appropriate approach to emergency treatment is chosen, because cortico-steroids, antihistamines, and epinephrine are ineffective in the treatment of acute attacks of angioedema. Although angioedema attacks can occur without any specific precipitating factor, in 50% of cases the precipitating cause is tissue trauma. Trigger factors include dental procedures, endotracheal intubation, surgical or diagnostic interventions in the cephalic or cervical region (such as oral or maxillofacial surgery and tonsillectomy), mental or physical stress, infection, hormonal changes (menstruation, pregnancy, intake of oral contraceptives), intake of specific drugs (such as estrogens or angiotensin-converting enzyme inhibitors) or foods containing histamine or able to induce histamine release, insect bites, and strong temperature variation. At present, it is possible to intervene with a specific therapy according to the patient’s needs.