Q. I've never had allergies until the past two summers, when I was hit hard by hay fever. Is it possible to develop allergies in adulthood?

A. In general, allergies are passed down with the family genes and symptoms begin in childhood, after one to two years of exposure to pollens, molds, dust mites or animals. Even though the symptoms begin in childhood, they may not become serious enough to be recognized as a disease until teen years or later.

There are, however, people who truly develop their allergies as adults. Examples of these are women who have their first symptoms during or shortly after pregnancy. Moving to a new location, where pollens or molds are more severe (West Michigan, for example), may cause symptoms to appear in a person who previously experienced none. Lastly, obtaining your first animal as an adult may ignite previously unnoticed allergies. Usually, food allergies are early childhood problems that tend to recede with age, but they are occasionally seen in adult years.

It is easy to confuse allergies with "sensitivities," which produce symptoms that mimic allergies, but—unlike allergies—do not involve the immune system. Examples are problems with cigarette smoke, perfumes, weather changes and occasionally hormones. As these sensitivities take many years to develop, they are rarely seen in children.

Allergies may produce varied symptoms and involve several different systems in the body. If the symptoms don't respond to simple treatment, an evaluation by a specialist should be sought to determine if an allergy is the cause.