Allergic Reaction

Table of Contents
OverviewMild to Moderate SignsFirst AidMonitor for Anaphylaxis

Overview

An allergic reaction occurs when the immune system reacts to something such as food, medicine, insect venom, latex, or another trigger. Mild symptoms can settle, but any reaction can progress.

Mild to Moderate Signs

  • Itchy rash, hives, or redness
  • Swelling of the lips, face, or eyes without breathing difficulty
  • Tingling mouth
  • Abdominal pain or vomiting, especially after exposure to a known allergen
  • Sneezing, watery eyes, or runny nose

First Aid

  • Follow DRSABCD if the person is unwell.
  • Stop contact with the likely allergen if safe.
  • Help the person follow their allergy action plan.
  • Give an antihistamine if it is available and appropriate for that person or their plan.
  • Keep watching for any worsening symptoms.

Monitor for Anaphylaxis

Treat the reaction as anaphylaxis and act immediately if the person develops:

  • Difficult or noisy breathing
  • Swelling of the tongue or throat
  • Wheeze, persistent cough, or voice change
  • Pale, floppy, confused, or collapsed appearance
  • Dizziness, faintness, or loss of consciousness
Last updated: 11/07/2026