Allergies can develop at any age, possibly even in the womb. They commonly occur in children, but may give rise to symptoms for the first time in adulthood. Asthma may persist in adults while nasal allergies tend to decline in old age.
Why, you may ask, are some people "sensitive" to certain allergens while most are not? Why do allergic people produce more IgE than those who are non-allergic? The major distinguishing factor appears to be heredity. For some time, it has been known that allergic conditions tend to cluster in families. Your own risk of developing allergies is related to your parents' allergy history. If neither parent is allergic, the chance that you will have allergies is about 15%. If one parent is allergic, your risk increases to 30% and if both are allergic, your risk is greater than 60%.
You come home after a day away, step into the house, and the symptoms hit: Watery eyes, scratchy throat, congestion. Could it be indoor allergies?
Allergies are very common. An estimated 50 million Americans are allergic to everything from dust and dander, to mold and mites.
But what about you? How can you be sure you have indoor allergies -- and pinpoint what’s causing them? To help you understand what’s behind your allergy symptoms, WebMD got tips from experts on how to recognize common allergy...
Although you may inherit the tendency to develop allergies, you may never actually have allergy symptoms. You also do not necessarily inherit the same allergies or the same diseases as your parents. It is unclear what determines which substances will trigger a reaction in an allergic person. Additionally, which diseases might develop or how severe the symptoms might be is unknown.
Another major piece of the allergy puzzle is the environment. It is clear that you must have a genetic tendency and be exposed to an allergen in order to develop an allergy. Additionally, the more intense and repetitive the exposure to an allergen and the earlier in life it occurs, the more likely it is that an allergy will develop.
There are other important influences that may be associated with allergic conditions. Some of these include smoking, pollution, infection, and hormones.