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Table 1 Diagnostic criteria for anaphylaxis, adapted [1]

From: How to manage anaphylaxis in primary care

Diagnostic criteria for 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 (e.g., generalized hives, pruritus or flushing, swollen lips–tongue–uvula and at least one of the following
 a. Respiratory compromise (e.g., dyspnea, wheeze–bronchospasm, stridor, reduced PEF, hypoxemia)
 b. Reduced BP or associated symptoms of end-organ dysfunction (e.g., hypotonia [collapse], syncope, incontinence)
2. Two or more of the following that occur rapidly after exposure to a likely allergen for that patient (minutes to several hours)
 a. Involvement of the skin–mucosal tissue (e.g., generalized hives, pruritus, flushing, swollen lips–tongue–uvula
 b. Respiratory compromise (e.g., dyspnea, wheeze–bronchospasm, stridor, reduced PEF, hypoxemia)
 c. Reduced BP or associated symptoms (e.g., hypotonia [collapse], syncope, incontinence)
 d. Persistent gastrointestinal symptoms (e.g., crampy abdominal pain, vomiting)
3. Reduced BP after exposure to known allergen for that patient (minutes to several hours)
 a. Infants and children: low systolic BP (age specific) or > 30% decrease in systolic BPa
 b. Adults: systolic BP of < 90 mmHg or > 30% decrease from that person’s baseline
  1. PEF peak expiratory flow, BP blood pressure
  2. aLow systolic blood pressure for children is defined as < 70 mmHg from 1 month to 1 year, less than (70 mmHg + [2 × age]) from 1 to 10 years, and < 90 mmHg from 11 to 17 years