An allergic reaction can range from mild and short-lived to a whole-body emergency needing adrenaline within minutes. The severity of any single reaction cannot be predicted from the dose, the trigger, or the person’s previous reactions. Adrenaline lets someone with no medical training reverse a severe allergic reaction.
Signs and Symptoms of a Severe Allergic Reaction and Anaphylaxis
An allergic reaction occurs when the body’s immune system treats a harmless substance as a threat. Look for swelling of the lips, face, or eyes, hives or welts on the body, a tingling mouth, and stomach pain or vomiting in the cases of stings or food allergy.
Anaphylaxis is a severe reaction. It involves the airway, breathing, or circulation, and any one of the following signs is enough to call it anaphylaxis:
Difficult or noisy breathing
Swelling of the tongue
Swelling or tightness in the throat
Difficulty talking or a hoarse voice
Wheeze or persistent cough
Persistent dizziness or collapse
Pale and floppy (young children)
Abdominal pain or vomiting (for insect or medication allergy)
The Point at Which an Allergy Becomes a Medical Emergency
The shift from a mild allergic reaction to an emergency is the appearance of any anaphylaxis sign. One sign is enough. A person with known allergy who suddenly has trouble breathing, even with no other anaphylaxis signs, must be treated as if anaphylaxis is happening. If anaphylaxis is suspected, follow these steps from the Australasian Society of Clinical Immunology and Allergy (ASCIA) action plan:
Lay the person flat on their back. Do not let them stand or walk. If it is hard for them to breathe, have them with their legs straight. If they are unconscious, roll them onto their side. Hold children flat and have pregnant women lie on their side instead.
Inject adrenaline or epinephrine into their outer mid-thigh, through clothes if necessary. Note the time the device was given.
Call triple zero (000) and ask for an ambulance.
If their symptoms have not improved after five minutes, give them a second adrenaline dose if possible,
Stay with the person until paramedics arrive. Be ready to start CPR if they stop breathing normally or become unresponsive.
What to Expect After Adrenaline
Adrenaline fixes the worst symptoms within minutes, but the reaction is not over. A second wave of reaction, called a biphasic reaction, can return up to 72 hours later, even after the first dose appears to have settled everything. For this reason, everyone given adrenaline goes to hospital, regardless of how well they appear afterwards.
The minimum hospital stay is four hours after the symptoms have resolved, longer for severe cases or anyone who needed a second dose. During that time, the medical team checks vital signs, watches for a return of symptoms, and writes a prescription for a replacement device before discharge. The used device stays with the patient and is handed to paramedics on arrival.
After discharge, the person’s GP or clinical immunology and allergy specialist reviews the trigger, updates their personal action plan, and arranges allergy testing if the cause is unclear. People reacting for the first time to a food, sting, or medicine are referred for specialist assessment, with a focus on identifying the trigger and confirming the right device for their weight. At home, family or housemates learn how to use the new device, which travels everywhere with the patient.
Get Trained with Accredited First Aid
An allergic reaction follows a recognisable course. Allergy first aid that holds up under pressure depends on practice. An accredited first aid course provides exactly that environment. Your enrolment is the move that takes allergy first aid from theory to response.
FAQs
How Does Allergy Testing Work?
In a skin prick test, a health professional draws a small drop of allergen extract is placed on the forearm and the skin is gently pricked through the drop. Blood tests measure specific antibodies.
How Common Are Food Allergies?
According to Allergy and Anaphylaxis Australia, roughly one in ten infants, one in twenty children aged 10 to 14, and one in fifty adults have a food allergy.
Is Hay Fever an Allergy?
Yes. Hay fever, known clinically as allergic rhinitis, is an immune response to inhaled allergens such as pollen, dust mite, mould spores, and animal dander, and it affects around one in four Australians.
