What is an allergy?
A person with an allergy has an immune system that over-reacts to a substance, such as a drug, dust, food, plant, or animal. The immune system, which normally fights infection, is stimulated by the substance. Stimulation of the immune system may result in swelling and irritation of the eyes, nasal membranes, lungs, skin, or intestines.

What are the symptoms of an allergy?
Allergy symptoms include itching, hives, rash, diarrhea, facial swelling, sneezing, runny nose, or wheezing.

How does the doctor treat an allergy?
Treatment for an allergy may include epinephrine injections, antihistamines, corticosteroids, and additional medications that reduce the symptoms of the allergy. Allergy shots may also reduce the symptoms of an allergy.