Allergies

Allergy is the term used to describe an adverse (bad) reaction by the body to a particular substance. Most things that cause allergies are not obviously harmful, and have no affect on people who are not allergic.

Allergies are very common and affect around one in four people in the UK at some time in their lives. The number of people affected by allergies rises
every year. For example, one study showed that number of children who
are allergic to nuts doubled in a ten year period.

The reason for the rise of allergies in unclear. Some experts have claimed that it is associated with pollution. Another theory is that it is a result of
us living in a cleaner, germ-free environment. By reducing the number of germs our immune system has to deal with, we have thrown it off balance, so that it over-reacts when it comes into contact with harmless substances.

There have been many studies trying to prove whether or not these theories are correct, but the results have been inconclusive and further
research is needed.

Read Here - for 'Allergens' and 'Allergic Reactions'.
http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=11&sectionId=1

You will also find links for - 'Symptoms' 'Causes' 'Diagnosis' and more.