An allergy is an adverse reaction that the body has to a particular food or substance in the environment. Any substance that triggers an allergic reaction is called an allergen.

There are thousands of allergens that can trigger allergies, but some of the most common include:

  • House dust mites
  • Grass and tree pollens
  • Pet hair or skin flakes
  • Fungal or mould spores
  • Food (particularly milk, eggs, wheat, soya, seafood, fruit and nuts)
  • Wasp and bee stings
  • Certain medication, such as penicillin
  • Latex
  • Household chemicals

An allergy develops when the body's immune system reacts to an allergen as though it is a threat, like an infection. It produces antibodies to fight off the allergen, in a reaction called the immune response.

Allergies are very common. According to Allergy UK, one-in-four people in the UK suffer from an allergy at some time in their lives. The numbers are increasing every year and as many as half of those affected are children.

Typical allergic reactions involve irritation and inflammation in the body. Symptoms may include:

  • Sneezing
  • Wheezing
  • Sinus pain (pressure or pain high up in the nose, around the eyes and at the front of the skull)
  • Runny nose
  • Coughing
  • Nettle rash (hives)
  • Swelling
  • Itchy eyes, ears, lips, throat and palate (roof of mouth)
  • Shortness of breath
  • Sickness, vomiting and diarrhoea

The nature of the symptoms depends on how you came into contact with the allergen, for example you may experience problems with your airways if you breathe in pollen.

The most effective way of managing an allergy is to avoid all contact with the allergen causing the reaction. Taking medication can't cure your allergy, but it can treat the common symptoms

* The contents of this condition is for information purposes only.