Anaphylaxis (say "ann-uh-fuh-LAK-suss") is a severe allergic reaction that affects the entire
body (systemic). It can occur within a few seconds or minutes after a person is
exposed to a substance (allergen or antigen).
Symptoms and signs of a severe allergic reaction may
Raised, red bumps on the
skin (hives or wheals).
Wheezing or difficulty
Rapid swelling, either in one area or over the entire body.
Swelling is most serious when it involves the lips, tongue, mouth, or throat
and interferes with breathing.
Belly pain or cramps.
Nausea or vomiting.
blood pressure, shock, and unconsciousness.
The sooner symptoms occur after exposure to the substance, the more
severe the anaphylactic reaction is likely to be. An anaphylactic reaction may
occur with the first exposure to an allergen, with every exposure, or after
several exposures. An anaphylactic reaction can be life-threatening and is a
medical emergency. Emergency care is always needed for an anaphylactic
How this information was developed to help you make better health decisions.