Anaphylaxis Differential Diagnoses

Updated: May 16, 2018
  • Author: S Shahzad Mustafa, MD; Chief Editor: Michael A Kaliner, MD  more...
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Diagnostic Considerations

The clinical diagnosis of anaphylaxis is based on probability and pattern recognition. Anaphylaxis is considered likely to be present if any 1 of the 3 following clinical criteria is satisfied within minutes to hours:

  • Acute symptoms involving skin, mucosal surface, or both, as well as at least one of the following: respiratory compromise, hypotension, or end-organ dysfunction

  • Two or more of the following occur rapidly after exposure to a likely allergen: hypotension, respiratory compromise, persistent gastrointestinal symptoms, or involvement of skin or mucosal surface

  • Hypotension develops after exposure to an allergen known to cause symptoms for that patient: age-specific low blood pressure or decline of systolic blood pressure of more than 30% compared to baseline

However, anaphylaxis occurs as part of a clinical continuum that can begin with relatively mild features and rapidly progress to life-endangering respiratory or cardiovascular manifestations. Delaying the diagnosis until multiorgan manifestations of anaphylaxis are present is risky because the severity of a reaction is difficult or impossible to predict at the time of symptom onset.

Other problems to be considered in diagnosing potential anaphylaxis include the following:

  • Vasodepressor (vasovagal) reaction (probably the most common masquerader)

  • Globus hystericus

  • Hereditary angioedema

  • Other forms of shock (ie, hypovolemic, cardiogenic, septic)

  • Flushing syndrome, including red man syndrome (vancomycin), pancreatic polypeptide tumors, postmenopausal patient, ethanol-induced, autonomic epilepsy

  • Monosodium glutamate poisoning

  • Scombroid fish poisoning

  • Capillary leak syndrome

  • Myocardial dysfunction

  • Foreign body aspiration (young children, especially)

  • Poisoning, acute

  • Neurologic (stroke, seizure)

Nonorganic disease, including panic attack, hyperventilation, vocal cord dysfunction syndrome, somatoform anaphylaxis

Differential Diagnoses