ALLERGIES DEFINITION

Hay fever, the common name for respiratory allergies, is your body's reaction to irritants in the air. Normally your immune system fights off only those things that threaten your health, such as cold viruses and cancer cells. But like a hypersensitive smoke detector, an allergic person's immune system sounds the alarm at the slightest provocation, sending off waves of the chemical histamine to fend off the presumed offender. Unfortunately, the side effects of histamine are the symptoms we associate with allergies: a runny nose and sneezing, itchy nose and throat, watery red eyes, and congestion.