Information for the public
Anaphylaxis
Anaphylaxis
Anaphylaxis is a serious allergic reaction that happens quickly and can lead to potentially life-threatening problems with breathing or blood circulation. Most patients also have a rash (redness of the skin and/or hives) or swelling. Well-known causes of anaphylaxis include food (for example, nuts) and insect venom. Allergic reactions to drugs or, less commonly, latex may also result in anaphylaxis. Food is a particularly common trigger in children, while drugs are much more common triggers in older people. In a large number of cases, especially in adults, there is no identifiable cause and this is known as idiopathic anaphylaxis.
After an anaphylactic reaction, there is often a risk of this happening again in the future. Further investigation is therefore needed in all cases to try to identify the cause and assess the risk of the person having another anaphylactic reaction.
In a severe allergic reaction, cells called 'mast cells' start to rapidly release chemicals into the circulation, from where they are rapidly carried throughout the body. These chemicals include histamine, which is responsible for many of the symptoms of an allergic reaction, and an enzyme called tryptase. Taking blood samples at the time of the anaphylactic reaction enables the amount of tryptase released from the mast cells to be measured later. This can then help to confirm whether you (or your child) had an anaphylactic reaction.