Many people wonder what causes their allergic symptoms, and why they are worse at certain times.
Allergies begin when your body becomes sensitive to a certain substance called an antigen or allergen. The reaction of allergens with antibodies causes sensitized body cells to release histamine and similar substances. These products of the allergic reaction can cause many kinds of symptoms - runny noses and tearing eyes, nasal congestion and head pressure, itching mucous membranes, chest tightness and wheezing, abdominal cramps, and many others. No one knows for sure why some people are allergic and others are not. The tendency to develop allergies is much greater in persons with a strong family history of allergic disorders.