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Table 1 Clinical Criteria for Diagnosing Anaphylaxis

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

Anaphylaxis is highly likely when any one of the following three criteria is fulfilled
1. Acute onset of an illness (minutes to several hours) with involvement of the skin, mucosal tissue, or both (eg, generalized urticaria, itching or flushing, swollen lips-tongue-uvula)
   AND AT LEAST ONE OF THE FOLLOWING:
   A) Respiratory compromise (eg, dyspnea, wheeze-bronchospasm, stridor, reduced PEF, hypoxemia)
   B) Reduced blood pressure or associated symptoms of end-organ dysfunction (eg. hypotonia [collapse], syncope, incontinence) OR
2. Two or more of the following that occur rapidly after exposure to a likely allergena for that patient (minutes to several hours)
   A) Involvement of the skin-mucosal tissue (eg, generalized urticaria, itch-flush, swollen lips-tongue-uvula)
   B) Respiratory compromise (eg, dyspnea, wheeze-bronchospasm, stridor, reduced PEF, hypoxemia)
   C) Reduced blood pressure or associated symptoms (eg, hypotonia [collapse], syncope, incontinence)
   D) Persistent gastrointestinal symptoms (eg, crampy abdominal pain, vomiting) OR
3. Reduced blood pressure after exposure to known allergenb for that patient (minutes to several hours)
   A) Infants and children: low systolic blood pressure (age-specific) or greater than 30% decrease in systolic blood pressurec
   B) Adults: systolic blood pressure of less than 90 mm Hg or greater than 30% decrease from that person's baseline
  1. PEF: peak expiratory flow.
  2. aOr other trigger, for example, immunologic but IgE-independent, or nonimmunologic (direct) mast cell activation.
  3. bFor example, after an insect sting, reduced blood pressure might be the only manifestation of anaphylaxis; or, in a similar example, during allergen immunotherapy, after injection of a known allergen for that patient, generalized urticaria (only one body organ system affected) might be the only initial manifestation of anaphylaxis.
  4. cLow systolic blood pressure for children is defined as less than 70 mm Hg from 1 month to 1 year, less than (70 mm Hg +[2 × age]) from 1 to 10 years, and less than 90 mm Hg from 11 to 17 years. Normal heart rate ranges from 80-140 beats/min at age 1-2 years; from 80-120 beats/min at age 3 years; and from 70-115 beats/min after age 3 years. Infants are more likely to have respiratory compromise than hypotension or shock, and in this age group, shock is more likely to be manifest initially by tachycardia than by hypotension.
  5. Clinical criteria 1, 2, and 3 are taken from reference [2].
  6. References [33] and [34] support footnotes b and c, respectively.