Life-threatening allergic reactions. Anticipating and preparing are the best defenses.

The sudden development of anaphylaxis or an anaphylactoid reaction is a medical emergency. It can cause death from upper airway edema and asphyxia, especially if the patient is at high risk (eg, has cardiac disease or bronchial asthma) and does not seek prompt attention or know how to administer self-treatment. Among the most common causes are administration of certain drugs and biologic agents, exposure to radiographic contrast media, ingestion of particular foods (eg, shellfish, nuts), and insect stings. Dr Stafford describes clinical manifestations of severe allergic reactions that aid in its diagnosis, the many possible causes, a treatment protocol, and preventive measures.