"Allergies are all in your head."
"Once you have allergies, you have them for life."

These are just some of the misconceptions about allergies that Michael Schatz, MD, hears from his patients. Schatz is the chair of the Public Education Committee of the American Academy of Allergy, Asthma and Immunology; staff allergist at Kaiser Permanente Medical Center in San Diego; and a clinical professor in the Department of Medicine at the University of California San Diego School of Medicine.

Q. Do you find that some people don't take allergies seriously?

A. There are a number of common misconceptions. People think that asthma in particular, but other allergies too, are psychosomatic. People who aren't allergic walk out in the air and don't start sneezing. They can't understand that another person gets symptoms from doing the same thing. They dismiss it as psychosomatic. But medically, this does not appear to be the case. Fortunately, this is a declining misconception.

Q. Do people mistake other problems for an allergy?

A. People think that if some specific agent causes a problem, then that's an allergy. Certainly, having a specific agent cause something is an essential part of an allergy, but it's not all. You also have to show that the person has some sort of allergic antibody or other immunological response against that substance. For example, take a person who drinks milk and gets diarrhea. You've got the agent -- the milk -- but it's only an allergy if you can show that the person has an antibody to the milk. A person with diarrhea after milk may be lactose intolerant (lacking enough lactase enzyme to digest the milk) and that's not an allergy. Or take someone who experiences nausea when they take erythromycin (an antibiotic medicine). That's not necessarily an allergy. Medicines can cause a number of side effects, and those are different from an allergy.