Allergies

Here are some typical signs of allergies:

• Sneezing, often accompanied by a runny or clogged nose
• Coughing and postnasal drip
• Itching eyes, nose, and throat
• Allergic shiners (dark circles under the eyes caused by increased blood flow near the sinuses)
• The "allergic salute" (in a child, persistent upward rubbing of the nose that causes a crease mark on the nose)
• Watering eyes
• Conjunctivitis (an inflammation of the membrane that lines the eyelids, causing red-rimmed, swollen eyes, and crusting of the eyelids)

What causes allergies?

In people who are not sensitive to airborne allergens, the mucus in the nasal passages routinely moves foreign particles to the throat, where they are swallowed or coughed out. But something different happens to a person with allergies. The immune system of people with allergies overreacts to allergens as if they were invading the body. To combat the allergen, the immune system responds with an antibody called immunoglobulin E (IgE). IgE prompts certain cells in the body to release chemicals, including histamine, which are responsible for the familiar allergic responses like itching, swelling, and redness.

Allergy genetics

Allergies have a genetic component. Scientists believe that the tendency toward allergies is inherited, but not the tendency to be allergic to a particular substance. If you have allergies, such as hay fever, eczema, or asthma, your children may also be at risk for some sort of allergy down the line -- even if they don’t yet have symptoms. It can take several years of exposure to an allergen for the first reactions to occur in a susceptible individual. If you’re a parent with allergies of any kind, it’s important to know whether the levels of other allergens in your home are high enough to provoke an allergic response.

Allergies seem to be more common than ever. Energy efficient homes may pose increased risks for allergen buildup. Less drafty windows and doors are good for holding down energy consumption, but limit the exchange of indoor air with fresh outside air. Forced air furnaces re-circulate the same air – and the same airborne allergens -- throughout the house. As a result, allergies can be more severe in the winter months when the heat is running.