Allergy is used to describe a response within the body to a substance (known as an allergen) that is not necessarily harmful in itself but results in an immune response and a reaction that causes unwanted symptoms and disease.

Common allergens include pollen from trees and grasses, house dust mites, moulds, cats and dogs, wasp and bee stings, some medicines and certain foods such as nuts, fish or eggs.

An allergic person’s immune system judges certain allergens to be damaging and so produces a special type of antibody (IgE) to attach the invading material. This leads other blood cells to release further chemicals (including histamine) which together cause the symptoms of an allergic reaction.

Common symptoms include:

  • Coughing and sneezing
  • Runny nose
  • Sinus problems
  • Itchy eyes and ears
  • Rash
  • Shortness of breath
  • Severe wheezing

Allergy affects one in four people at some time in their lives, and in the UK, this figure is rising by 5% every year – half of these being children.

How is it diagnosed?

A simple skin prick test will provide quick and simple results within 15 to 20 minutes.

Blood tests can also be performed by the Immunology Department. The test measures the amount of specific IgE  present in the blood for the allergen. Results range from class zero (negative result) to class 6 (severe).


A doctor will usually prescribe a treatment that is specific to the allergy in question. Prescribed medicines often contain antihistamines as a means of limiting the body’s response to the allergy.