Anaphylaxis is a sudden onset, rapidly progressive, life-threatening systemic hypersensitivity reaction. Immunological and non-immunological mechanisms cause anaphylaxis. Factors that play a role in the etiology of anaphylaxis differ according to age groups. In general, the diagnosis of anaphylaxis is made by a careful history and physical examination. Epinephrine is the life-saving first-choice treatment in anaphylaxis. All patients and their families should be educated about anaphylaxis and how to use adrenaline autoinjectors.