The term allergy is used to describe a response, within the body, to a substance which is not necessarily harmful in itself, but results in an immune response and a reaction that causes symptoms and disease in a predisposed person, which in turn can cause inconvenience, or a great deal of misery.
An allergy is everything from a runny nose, itchy eyes and palate to skin rash. It aggravates the sense of smell, sight, taste and touch causing irritation, extreme disability and sometimes fatality. It occurs when the body's immune system overreacts to normally harmless substances.
Allergy is widespread and affects approximately one in four of the population in the UK at some time in their lives. Each year the numbers are increasing by 5% with as many as half of all those affected being children.
Intolerance and Sensitivity
Allergy is commonly used to describe any unpleasant reaction to a drug, food, insect sting or chemical, this can be misleading. The word should only really be used to describe a reaction produced when the body meets a normally harmless substance, which has been remembered from a previous exposure and subsequently produces the IgE antibody.
Sensitivity is a reaction to a substance, which is an exaggeration of a normal side effect produced by that substance. For example, reliever inhalers used in asthma, if given at too high a dose in a particular individual may cause them to shake.
Intolerance happens when unpleasant symptoms occur after eating a substance, which your body cannot handle because the digestive system does not produce sufficient quantities of a particular enzyme/chemical, which is needed to break down the food and aid digestion.