(CNN) -- Have you ever experienced itchiness or hives in your
mouth area after eating raw fruit or vegetables? Do you also
have seasonal allergies? People with allergies to birch pollen
may have associated allergies to raw apples. If so, you may have
oral allergy syndrome, whose symptoms occur because the proteins
in some fruits and vegetables are similar to proteins in some
pollens. "They're not identical proteins, but they're similar
enough to confuse the immune system to have these reactions,"
said said Dr. Robert Wood, chief of pediatric allergy and
immunology at Johns Hopkins Children's Center. That's not to say
that everyone with pollen allergies has oral allergy syndrome. A
person may sneeze all spring long and not have any obvious food
sensitivities. But oral allergy syndrome may help explain why
some people have seemingly mysterious reactions to certain foods
-- for example, raw apples but not cooked apples. That's because
there are proteins in raw apples that are very similar to the
proteins in birc