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The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 71

85. What is the difference between an anaphylactic reaction and an anaphylactoid reaction?

  • Anaphylaxis is an old term. It has been defined in a number of ways over time.
  • From the 1980s-mid 2000s, that term was typically reserved for cases involving an IgE allergy. If a patient had a life threatening, multisystem allergic reaction from an IgE trigger, that event was called anaphylaxis. Similar reactions that were from a trigger that was not an IgE allergy were called anaphylactoid, which literally means “like anaphylaxis.”
  • In the mid 2003, the World Allergy Organization recommended that the term “anaphylactoid” be abanded. Whereas anaphylaxis had been mostly used to describe IgE reactions, their recommendation was to call all of these events anaphylaxis regardless of whether or not they were from IgE triggers. Anaphylaxis from an IgE trigger was called “immunologic anaphylaxis” and anaphylaxis from a non-IgE trigger was called “non-immunologic anaphylaxis.”
  • These terms are still used, but many providers just use the term anaphylaxis without specifying further.
  • Unfortunately, the recommendation to stop using “anaphylactoid” has not been fully adopted, despite repeated statements from professional organizations supporting it.
  • Part of why the definition of anaphylaxis was amended to be inclusive of all triggers was to encourage more effective treatment. A significant number of providers felt that anaphylactoid described a reaction that was self limiting or that was not serious enough to require epinephrine, despite the fact that treatment should have been the same as for anaphylaxis from any trigger. Moving away from the term “anaphylactoid” helped to confer the understanding that all forms of anaphylaxis were serious, that they required adequate treatment, and that there should not be an expectation that the reaction would resolve without treatment.
  • Mast cell patients ask me often if their “anaphylaxis from mast cell disease” is really anaphylaxis or if it is an anaphylactoid reaction. Per the World Allergy Organization, the term “anaphylactoid” is obsolete, so these patients experience anaphylaxis. But some providers do not recognize this as anaphylaxis.
  • The most important thing to impress upon providers is that regardless of the terminology they prefer, mast cell reactions that are anaphylactic/anaphylactoid still require the same, aggressive treatment. Calling a reaction anaphylactoid does not make it less serious or negate the requirement for advanced treatment.
  • This is an excellent resource for anyone wanting to learn more about the treatment recommendations for anaphylaxis. There are notes about the discussion on use of “anaphylactic” and “anaphylactoid” on page 344.


For additional reading, please visit the following posts:

The definition of anaphylaxis

Anaphylaxis and mast cell reactions