What are allergies?
Allergies are an abnormal response of the immune system. People who have allergies have an immune system that reacts to a usually harmless substance in the environment. This substance (pollen, mould, dust, etc.) is called an allergen.
Allergies are common, according to Allergy UK, one in four people in the UK suffers from an allergy at some point in their lives.
No one knows why some people develop allergies, but they may be inherited. Allergies may flare up and subside throughout your life.