An allergy is a genetic condition that causes the body to respond to harmless substances in the environment as though they are harmful to the body. These substances are referred to as allergens. The body’s immune system recognizes the presence of allergens and starts a reaction to prevent their invasion. In most people, this is not a problem. However, in some the immune system is overactive and identifies normally harmless particles as dangerous, producing an excessive reaction that actually causes inflammation. This inflammation is referred to as allergic rhinitis. Symptoms include: nasal congestion, sneezing, itchy/watery eyes, and runny nose.