APA Dictionary of Psychology

n. hypersensitivity to the introduction of a substance (e.g., a food item such as peanuts or a drug such as penicillin) into body tissues, resulting from previous exposure to it. Symptoms, such as breathing difficulties and wheezing, are sudden, and anaphylactic shock—pulmonary edema, heart arrhythmia, shock, loss of consciousness, and potential respiratory or cardiac arrest—may occur if untreated. —anaphylactic adj.