An allergy refers to an over-reaction by the bodys immune system to certain substances called allergens that are inhaled, swallowed, or come in contact with the skin. An estimated 50 million Americans are affected by allergies. Common allergens include animal dander, dust mites, insect bites, medications, mold spores, and pollen. Common signs of allergy include sneezing, wheezing, watery eyes or cold symptoms that last more than 10 days without a fever, repeated ear and sinus infections, loss of smell or taste, frequent throat clearing, hoarseness, coughing or wheezing, and dark circles under the eyes caused by increased blood flow near the sinuses, among others.

Content last modified on May 13, 2005