Anaphylaxis is very likely when any one of these 3 criteria are met:

Acute onset (within minutes to 3 hours) of rapidly progressive symptoms involving the skin, mucosal tissue, or both (examples include: generalized hives, pruritus, flushing, swollen lips or tongue) and at least one of the following:

• Respiratory symptoms (dyspnea, wheezing, stridor)

• Hypotension or associated symptoms of end-organ dysfunction (syncope, collapse)

Two or more of the following that occur rapidly after likely exposure to an allergen (within minutes to 3 hours):

• Skin-mucosal involvement (generalized hives, pruritis, flushing, swollen lips or tongue)

• Respiratory symptoms (dyspnea, wheezing, stridor)

• Hypotension or associated symptoms of end-organ dysfunction (syncope, collapse)

• Gastrointestinal symptoms (vomiting, crampy abdominal pain)

Reduced blood pressure after exposure to known allergen for that patient (within minutes to 3 hours)

• This scenario most often involves a patient with known environmental allergies who received an allergen immunotherapy subcutaneous injection immediately prior