What is an allergy?

An allergy or allergic reaction happens when the body’s immune system over-reacts to an external substance that would generally be considered harmless.

The immune system is designed to protect your body from foreign invaders that can cause damage. When a foreign substance like a virus enters the body, the immune system launches into action to help fight off the infection. When the immune system over-reacts to typically harmless foreign substances (called allergens), we call this an allergy.

A substance that is an allergen for one person may not be for another, as everyone reacts differently. The likelihood of developing allergies is increased if other family members suffer from allergy or suffer from allergies or other respiratory conditions.

Common allergens include:

  • dust and dust-mites
  • air-borne pollen and grasses
  • animal dander particularly from cats and dogs
  • household moulds
What triggers an allergy?