Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death. It typically causes a number of symptoms including an itchy rash, throat swelling, and low blood pressure. Common causes include insect bites/stings, foods, and medications.
On a mechanistic level, anaphylaxis is caused by the release of mediators from certain types of white blood cells triggered either by immunologic or non-immunologic mechanisms. It is diagnosed on the basis of the presenting symptoms and signs. The primary treatment is injection of epinephrine, the administration of intravenous fluids, and positioning the person flat, with other measures being complementary. Worldwide, 0.05–2% of the population is estimated to have anaphylaxis at some point in life, and rates appear to be increasing.