An allergy is where your body reacts to something that's normally harmless like pollen, dust or animal fur. The symptoms can be mild, but for some people they can be very serious.

Causes of allergies

Things that cause allergic reactions are called allergens.

Common allergens include:

Check if it's an allergy

Symptoms of an allergic reaction can include:

Immediate action required: Call 999 if:

  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction (anaphylaxis) and may need immediate treatment in hospital.


If you have an adrenaline auto-injector

If you or someone you're with is having a serious allergic reaction and has an adrenaline auto-injector (such as an EpiPen), you should use it immediately.

Instructions are included on the side of the injector if you forget how to use it or someone else needs to give you the injection.

Call 999 for an ambulance after using the injector, even if you or the person you're with seems to be feeling better.

Non-urgent advice: See a GP if:

  • you think you or your child may have an allergy

What happens at your appointment

A GP may arrange some allergy tests or refer you to a specialist allergy clinic to have them.

Tests you may have include:

Treatments for allergies

Treatments for allergies include:

Your specialist will give you an allergy management plan that will explain how to manage your allergy.


Find out more

Allergy UK: living with an allergy

Page last reviewed: 2 August 2022
Next review due: 2 August 2025