Anaphylaxis is a generalized or systemic hypersensitivity reaction, life-threatening, mainly mediated by immunoglobulin E (IgE) antibodies after previous sensitization of the affected patient. Anaphylactoid reaction refers to those not IgE mediated, but this term is out of data since there is no difference in treatment. In practice, anaphylaxis is characterized by a cardiopulmonary collapse of rapid onset with high mortality potential following exposure to an antigen. Early recognition is essential since prompt administration of epinephrine is directly related to the positive outcome of this condition. This review seeks to elucidate anaphylaxis and to create a practical flowchart for the recognition and early treatment of this condition.