A sudden, severe allergic reaction characterized by a sharp drop in blood pressure, urticaria, and breathing difficulties that is caused by exposure to a foreign substance, such as a drug or bee venom, after a preliminary or sensitizing exposure. The reaction may be fatal if emergency treatment, including epinephrine injections, is not given immediately. Also called anaphylaxis. a very sudden serious physical reaction that is caused by an allergy to something such as nuts, eggs, or the sting of some insects. The reaction causes shock, breathing difficulties, and sometimes death
a severe and rapid and sometimes fatal hypersensitivity reaction to a substance (especially a vaccine or penicillin or shellfish or insect venom) to which the organism has become sensitized by previous exposure
An allergic reaction marked by contraction of smooth muscle and dilation of blood vessels If not checked rapidly by an injection of epinephrine, the reaction can be lethal
A life-threatening allergic reaction characterized by a swelling of body tissues including the throat, difficulty in breathing, and a sudden fall in blood pressure