An allergy is a reaction by your immune system to something that does
not bother most other people. People who have allergies often are
sensitive to more than one thing. Substances that often cause reactions
Normally, your immune system fights germs. It is your body's defense
system. In most allergic reactions, however, it is responding to a false
alarm. Genes and the environment probably both play a role.
Allergies can cause a variety of symptoms such as a runny nose, sneezing, itching, rashes, swelling, or asthma. Allergies can range from minor to severe. Anaphylaxis
is a severe reaction that can be life-threatening. Doctors use skin
and blood tests to diagnose allergies. Treatments include medicines,
allergy shots, and avoiding the substances that cause the reactions.