Summary (for those using text-reading software)

An allergy is a response to a substance (allergen) which may not, in itself be harmful but which creates an immune response and a reaction in the body which can result in symptoms and disease.

Common allergens include: dust mites, pollen, moulds, cats & dogs, wasps & bee stings, certain medicines and certain foods.

An allergy results when the body's immune system, believing itself to be under attack, produces a special type of antibody. This leads other blood cells to release further chemicals (including histamine), which can produce the symptoms of an allergic reaction.

Common symptoms include: sneezing, runny nose, itchy eyes & ears, wheezing, coughing, shortness of breath, sinus problems.

Allergies affect about 25% of the UK population and this figure is rising by about 5% each year, with half of these being children.

Diagnosis is usually conformed by skin-prick testing. This introduces a tiny amount of allergen into the skin. It is quick and simple and produces results in about 15 or 20 minutes. Blood tests can also be used within immunology departments.

Treatment will depend on the type and severity of the allergy and will usually be prescribed by a doctor. Normally, the medication contains anti-histamines.

By Seema Chudusama.