Health Information

Allergic reactions occur when the immune system encounters and overreacts to substances that are not genuinely harmful. These substances are called allergens.

In people who have nasal allergies, the immune system reacts to an airborne (inhaled) allergen by creating an antibody called immunoglobulin E, or IgE, that is designed to fight that specific allergen. This antibody-allergen complex attaches to certain cells in the nasal passages and causes the release of chemicals including histamine, which in turn cause inflammation.

The end result is nasal allergy symptoms—congestion, sneezing, and an itchy or runny nose. Some common examples of inhaled allergens are airborne pollens from some plants and trees, mold spores, and dog and cat dander.

Allergies and genetics

Just like many of your physical characteristics—such as hair or eye color and height—your susceptibility to allergies may be inherited. However, even with a genetic tendency, you don't automatically get allergies. Several factors must also be present in order for a person to develop an allergic sensitivity. These include:

• Specific inherited genes
• Exposure to the allergens you are genetically predisposed to react to
• The amount of, and length of, exposure to the allergens

For instance, even with a genetic likelihood to develop an allergy to dust mites, it may take several years of exposure to the allergen before allergy symptoms appear. This is why, as people age, they sometimes develop allergies to substances in their environment.

Your likelihood of inheriting allergies

If one of your parents had allergies, you have about a 30 percent chance of inheriting allergic tendencies. If both of your parents had allergies, your chance of having allergies increases to 70 percent.