Allergies affect an estimated 40 to 50 million children and adults in the U.S. That's nearly one out of five people.

Hay fever, or allergic rhinitis, is commonly caused by allergies to pollen from trees, grasses, weeds or airborne mold spores.

Some people experience an allergic reaction to house dust, dust mites, animal dander or mold spores. While these tiny triggers are barely visible to the human eye, they can be found in nearly all homes to some degree.

Dust mites, tiny parasites that feed on the skin scales people shed, are the No. 1 in-home allergen problem for most allergy sufferers. Hundreds of dust mites live in just a single gram of dust, and an average one-year-old pillow contains more than 250,000 dust mites and their carcasses.

When a person with allergies inhales an allergen, the body's immune system reacts by triggering the nasal membranes to release histamine and other chemicals. Histamine dilates the small blood vessels of the nose, and fluids leak out into the surrounding tissues, causing runny noses, nasal congestion, watery eyes, itching, swelling and other allergy symptoms. Itching and sneezing are your immune system's natural attempt to rid your body of its enemies, including allergens.

There is no specific cure for allergies, although researchers continue to search for a solution for allergy-sufferers. If you are bothered by allergies, your best bet is to be proactive about avoiding allergy triggers and use products that help alleviate allergy symptoms, such as Breathe RightŪ nasal strips to help you breathe better when allergies strike.