Table 1 Differential diagnosis of anaphylaxis

Anaphylaxis due to other allergenic or external exposures:

 Food (including scombroidosis), medication, insect venom, exercise, heat, cold, idiopathic.

Anaphylaxis due to excess histamine production:

 Systemic mastocytosis, mast cell activation syndromes.

Flushing syndromes

 Red man syndrome (vancomycin or other medication), carcinoid, postmenopausal, alcohol-related, vasoactive-peptide tumors (e.g. pancreatic VIPoma, medullary thyroid carcinoma).

Miscellaneous

 Vasovagal episodes, panic attacks, vocal cord dysfunction, C1 inhibitor deficiency syndromes (hereditary and acquired), pheochromocytoma, neurologic process (seizure/stroke), cardiovascular process (myocardial infarction, embolism), capillary leak syndrome, dehydration, hypoglycemia.