anaphylactoid reaction

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Related to anaphylactoid reaction: anaphylaxis, Anaphylactic reaction


resembling anaphylaxis.
anaphylactoid reaction a reaction resembling generalized anaphylaxis but not caused by IgE-mediated allergic reaction but rather by a nonimmunologic mechanism.

anaphylactoid reaction

An anaphylaxis-like reaction that occurs without an allergen-IgE antibody event, caused by a nonimmune release (e.g., reaction to radiocontrast, opiates, vancomycin, chymopapain, aspirin) of vasoactive and inflammatory mediators, including histamine.

anaphylactoid reaction

(an″ă-fĭ-lak′′toyd″) [ anaphylact(ic) + -oid]
A reaction that resembles anaphylaxis, e.g., by hives, laryngeal edema, or shock, but does not involve IgE antibodies or allergens and therefore is has no allergic basis.


This relatively uncommon type of reaction can be caused by exercise; as the result of the release of histamine when body temperature rises; by elevated endorphin levels; by ionic compounds such as contrast media that contain radiographic iodine or polymyxin B antibiotic; by solutions containing polysaccharides such as dextran; by morphine, codeine, or meperidine; and by NSAIDs. The term should not be used as a synonym for mild anaphylaxis produced by IgE-allergen reactions.


Anaphylactoid reactions produce hives and itching identical to those of anaphylaxis. Very rarely, severe anaphylaxis or anaphylactic shock occurs. Anaphylactoid reactions are treated with the same drugs used to treat anaphylaxis.

References in periodicals archive ?
Effects of beta-adrenergic and calcium antagonists on the development of anaphylactoid reactions from radiographic contrast media during cardiac angiography.
Since some opioid analgesics show differences in both the amount of histamine they release (65-68,72) and the anatomical sites where this action occurs (66-68,89,91,92), avoiding an anaphylactoid reaction may sometimes be effected by simply substituting one opioid drug for another; for example, substituting fentanyl for morphine following cutaneous release of histamine, or fentanyl or morphine for buprenorphine following histamine release in the lungs.
Whether hydromorphone-induced anaphylactoid reaction was caused by IgE-mediation or not, naloxone rapidly reversed the symptoms in our patient.
We wish to thank Dr Russell for his interest in our recent case report addressing unrecognised mastocytosis in a patient manifesting as an anaphylactoid reaction to the administration of iodinated radiocontrast material (1).
Anaphylactoid reaction to administration of iodinated contrast media is a well known phenomenon.
One of the 16 had an anaphylactoid reaction to morphine infusion, while the other 15 were determined to have had anaphylaxis secondary to operative exposures.
Acetadote is contraindicated in patients with hypersensitivity or previous anaphylactoid reactions to acetylcysteine or any components of the preparation.
Acute coronary syndrome accompanying mast cell activation from allergic, hypersensitivity, or anaphylactoid reactions was first described by Kounis and Zavras in 1991 and has been referred to as "allergic angina" or "allergic myocardial infarction" (1, 2).
Severe anaphylactoid reactions have been reported in four women receiving intravenous or oral ranitidine during labor (Br.
The 10 other birds likely died of cardiopulmonary collapse and anaphylactoid reactions.
The concurrence of ACS with conditions associated with allergic or hypersensitivity and anaphylactic or anaphylactoid reactions constitutes the Kounis syndrome (1).
Anaphylactoid reactions to cancer agents are often related to cytokine release secondary to the administration of monoclonal antibodies.