Hello,

I read an article at http://www.medical-health-care-information.com/encyclopedia/A/allergy.asp
regarding 'Allergy'. Article says that
An allergy can refer to numerous kinds of immune reactions including
Type I hypersensitivity in which a person's body is hypersensitive and
develops IgE type antibodies to usual proteins. When a person is
hypersensitive, these symptoms are known as allergens. The word
allergy derives from the Greek words allos meaning "other" and ergon
meaning "work".Allergy

An allergy is the result of the body's immune system reacting to a
material that is not common to the body. The general allergic
conditions include food fever, asthma, and skin allergies. The basic
cause of allergy is unknown; however, some believe the reactions stem
from a misguided immune system. The misguided immune system over
reacts to these foreign substances that is not harmful.

The people are suffered by the Allergic have very sensitivity about
the lot of things, and can be irritated by lots of different
substances including smoke, pollution, cooking smells, perfume and
strong odors. Children who are often exposed to passive smoking are
more at risk of developing allergic reactions. So they have to careful
about the such things, because the medicine give you a senselessness
about the such things by which you are feeling allergy.

I hope above information is helpful to you.

Regards,
Monica