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Table 4 Differential Diagnosis of Anaphylaxis

From: World Allergy Organization Guidelines for the Assessment and Management of Anaphylaxis

Common diagnostic dilemmas

Flush syndromes

   Acute asthmaa


   Syncope (faint)

   Carcinoid syndrome

   Anxiety/panic attack

   Autonomic epilepsy

   Acute generalized urticariaa

   Medullary carcinoma of the thyroid

   Aspiration of a foreign body


   Cardiovascular (myocardial infarctiona, pulmonary embolus)

Nonorganic Disease


   Vocal cord dysfunction



   Neurologic events (seizure, cerebrovascular event)

   Psychosomatic episode

Postprandial syndromes




   Pollen-food allergy syndromec




   Monosodium glutamate




   Food poisoning


Excess endogenous histamine


   Mastocytosis/clonal mast cell disorderse

   Nonallergic angioedema

   Basophilic leukemia

Hereditary angioedema types I, II, & III


ACE inhibitor-associated angioedema


   Systemic capillary leak syndrome


   Red man syndrome (vancomycin)


   Pheochromocytoma (paradoxical response)

  1. aAcute asthma symptoms, acute generalized urticaria, or myocardial infarction symptoms can also occur during an anaphylactic episode.
  2. bHistamine poisoning from fish, eg. tuna that has been stored at an elevated temperature; usually, more than one person eating the fish is affected.
  3. cPollen-food allergy syndrome (oral allergy syndrome) is elicited by fruits and vegetables containing various plant proteins that cross-react with airborne allergens. Typical symptoms include itching, tingling and angioedema of the lips, tongue, palate, throat, and ears after eating raw, but not cooked, fruits and vegetables.
  4. dDistributive shock may be due to anaphylaxis or to spinal cord injury.
  5. eIn mastocytosis and clonal mast cell disorders, there is an increased risk of anaphylaxis; also, anaphylaxis may be the first manifestation of the disease.
  6. Adapted from references [2, 2225, 31, 32, 91, 92].