Anaphylaxis is a term used to describe a severe allergic reaction. It
is not common, but it can be life-threatening and requires emergency care.
Symptoms may appear in a few seconds or minutes or be delayed for several hours
after contact with the substance that caused the reaction. The sooner symptoms
appear, the more severe the reaction is likely to be.
Symptoms or conditions that may occur when a person has a severe allergic reaction include: