An allergy is when your body reacts to something that does not bother most other people. For example, they may have a reaction to pollen, mold, dust mites, pet dander, food or medication. When they come in contact with these things their immune system releases chemicals such as histamine. These chemicals are responsible for their symptoms. People can be allergic to many different things, such as:
pets
foods
dust mites
mold
latex rubber
pollen
About 35 million Americans suffer from allergies to pollen. (Pollen is a powder made by flowering plants and trees.) Pollen allergy is also known as hay fever. It is one of the most common allergies. When we think of hay fever, we think of spring. But pollen grains can be in the air in the spring, summer, and fall. It just depends on the type of tree, grass, or weed.
How are allergies treated?
There is no cure for allergies. So people just have to learn to cope with them. Here are some choices for dealing with them:

Avoid the things that trigger allergies. (This is the best treatment.)

Use over-the-counter and prescription drugs
Get allergy shots
Use nasal sprays
Use air conditioners and filters
^{Note : Information herein is provided for informational purposes only and is not a substitute for professional medical advice. You should not use this information for diagnosing or treating a medical or health condition. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider. Please consult your healthcare provider before beginning any course of supplementation or treatment.}
Content Courtesy : www.fda.gov