The cardinal features of anaphylaxis are:
- Itchy, urticarial rash.
- Progressive, painless swelling (angioedema) about the face and mouth, which may be preceded by itchiness, tearing, nasal congestion or facial flushing.
- Gastrointestinal symptoms, including cramps/abdominal pain and vomiting.
- Sudden reduced blood pressure or symptoms of end-organ dysfunction (e.g., hypotonia and incontinence).
- In infants, symptoms may also include fussiness, irritability, drowsiness or lethargy.