Allergy is much more than just hay fever. It occurs when the body develops an abnormal activation of the immune system - called IgE - to what would otherwise be harmless substances, such as pollen, animal dander, mold, food, medication or even insect stings. In these people, their immune response overreacts by producing IgE to these substances, causing the illnesses from which they suffer.
Although most often thought of as a child's disease, allergy can affect people of all ages - from infants to the elderly. There is clearly a family predisposition, which implies a genetic basis. Indeed, the risk for developing an allergic condition is up to 10 times higher in children whose parents are also allergic.
Environmental exposures are important as well. Urban dwellers are more likely to have hay fever and/or asthma than those who live on a farm. This may occur because of the decreased exposure to certain types of environmental substances - called endotoxins - that comes from animal waste found in abundance in rural locations, such as farms with livestock.
Other factors influence the risk for developing hay fever, asthma and other allergic diseases. These include early exposure to table food (during the first six months of life), living in areas of high air pollution (especially ozone and diesel exhaust as seen in urban areas), excessive use of antibiotics early in life and exposure to tobacco smoke (especially for asthma).
The first line of defense is prevention. Keeping a child away from second hand smoke (and not smoking as the child ages), controlling air pollution exposure, limiting table food exposure in early infancy (4-6 months of age) and careful use of antibiotics for what may be viral colds instead of bacterial infections may all reduce the risk for developing allergic diseases.
If an individual develops an allergic disease, what can be done? Avoidance is the primary principle. This is particularly important for those substances that can be controlled - drugs, foods and animal dander. For things such as pollen and mold, total avoidance is often not possible, so minimizing exposures, such as controlling inside air during pollen season and humidity to minimize indoor mold, can be quite effective.
Some allergic conditions can be treated in many patients with over the counter medications. This is particularly true for hay fever (antihistamines, decongestants) and certain rashes (antihistamines, steroid creams). However, sometimes the symptoms are so severe or hang on so long that medical care should be sought.
Allergist-immunologists are physicians specially trained to care for allergic diseases of all kinds - hay fever, asthma, food allergy, drug allergy, insect sting allergy - as well as other conditions such as sinus disease, hives and life threatening systemic reactions called anaphylaxis, such as occurs after bee stings in sensitive people. A visit to the allergist will include a thorough history, physical exam, and, when needed, skin testing to define the specific allergic sensitivity.
The allergist-immunologist will prescribe the correct medications to control symptoms in patients with various allergies. This may include nose sprays, inhalers, ointments and even specific pills or capsules. All these medications are designed to reduce or eliminate symptoms, as well as to maintain control of the condition.
In certain patients with respiratory allergies (hay fever, asthma), allergy shots may be prescribed. These injections of small amounts of material from the substances causing the allergies can decrease, or sometimes even eliminate the patient's sensitivity.