An allergen is something that can trigger an allergic reaction. It might be a food, medicine, insect sting, latex product, animal dander, pollen, or dust mite. In first aid, knowing the likely allergen can help you understand why someone is reacting and how serious the situation may become.
What is an allergen?
An allergen is a substance that causes the immune system to overreact in a person with an allergy.
The allergen itself is not always harmful to most people. The problem is how the person’s immune system responds to it.
What are common allergens?
Common allergens include:
- foods such as peanuts, tree nuts, milk, egg, soy, wheat, seafood, sesame, and lupin
- insect stings or bites
- some medicines
- latex
- pollen
- dust mites
- animal dander
Different people react to different allergens.
What can happen after allergen exposure?
Exposure to an allergen can lead to an Allergic Reaction. That reaction may stay mild or become severe.
Possible signs include:
- itching
- rash or hives
- swelling
- vomiting or tummy pain
- wheeze or breathing trouble
- dizziness or collapse
The most severe form is Anaphylaxis.
Why does the word matter in first aid?
The word allergen helps explain the trigger behind the reaction.
For example:
- in a Food Allergy, the food is the allergen
- in some insect-sting reactions, the sting is the allergen trigger
- in medicine allergies, the medicine may be the allergen
Knowing the likely allergen can help first aiders remove exposure when it is safe to do so and understand why symptoms may be escalating.
What should you do if an allergen causes a serious reaction?
If exposure to an allergen causes severe symptoms:
- Move the allergen away if it is safe to do so.
- Help the person use a prescribed EpiPen or other adrenaline auto-injector if severe symptoms suggest anaphylaxis.
- Call
000in Australia. - Watch breathing and response closely.
The medicine in an EpiPen is Epinephrine, also called adrenaline.
If the person becomes Unresponsive, follow the breathing pathway:
- use the Recovery Position if they are breathing normally
- start CPR if they are not breathing normally
How is this page different from allergy pages?
This page explains the trigger term itself.
- Allergic Reaction explains the overall meaning of the reaction
- Allergic Reactions focuses on signs to notice
- Food Allergy focuses on one common allergen group
- Anaphylaxis covers the life-threatening emergency
Summary
An allergen is a substance that triggers an allergic reaction in someone with an allergy. Common allergens include foods, stings, medicines, latex, pollen, dust mites, and animal dander. In first aid, the main priorities are recognising when exposure has caused a serious reaction, using prescribed adrenaline if needed, and calling 000 for severe symptoms.
Sources reviewed
- ASCIA: First Aid Plan for Anaphylaxis
- ASCIA: anaphylaxis resources and action plans
- Triple Zero: official emergency calling guidance
Reviewed against current Australian allergy and emergency guidance by the First Aid Glossary Editorial Team. This article is general information and does not replace a person’s prescribed ASCIA Action Plan, emergency-operator directions, medical advice or hands-on first aid training.
