Anaphylaxis is a Medical Emergency. Onset and severity of anaphylaxis may vary considerably. Anaphylaxis usually begins within minutes of exposure to the causative agent, and, in general, the more rapid the onset, the more severe the overall course.
Anyone administering vaccine should be prepared to recognize and treat systemic anaphylaxis.

Signs and symptoms of Anaphylactic reactions include:

1. Cutaneous: pruritis, flushing, urticaria, angioedema
2. Respiratory: hoarse voice and stridor, cough, wheeze, dyspnea, cyanosis
3. Cardiovascular: rapid weak pulse, hypotension, arrhythmias
4. Gastrointestinal: cramps, vomiting, diarrhea, dry mouth

From: Red Book – 2021 Report of the Committee on Infectious Diseases, 32nd Edition, American Academy of Pediatrics.