What causes oral allergy syndrome?
A lot of people don't realize that there are cross-reactions between plants such as tree pollen and other substances. For instance, in the case of birch tree pollen, there's a direct cross-reaction with various fruits, particularly apples and peaches. When someone has an allergy, the allergy system cannot distinguish between the pollen of birch trees and substances in apple and the peach, plum, cherry, nectarine family. So what happens is, somebody eats apple or a peach, and immediately it encounters the allergy system in the mouth. It induces a lot of itching and tingling in the mouth.
It only happens with the raw fruits, because when they are cooked, either by baking or by sterilization, you break down this allergy protein. So people who have the oral allergy syndrome, particularly to fruits and occasionally to some melons or also carrots and celery, very commonly have allergy to birch tree pollen.
And if you treat those patients with allergy shots to tree pollen, including birch tree pollen, this oral allergy syndrome settles down a great deal. The oral allergy syndrome is also much greater in May. If someone is breathing in a lot of the pollen of birch trees in May, then their immune system and their allergy system revs up at that time and it makes them much more sensitive to eating apples or peaches then.
That's just one example of cross-reactions between pollens and various other food substances. For example, patients who are allergic to ragweed pollen in the fall often will have a cross-reaction allergy to chamomile and may have problems drinking chamomile tea.
When should a person who has seasonal allergies see a doctor?
In most cases, the symptoms of springtime allergies are fairly straightforward; nasal, eye symptoms, and can be handled certainly by over-the-counter medications, or if not, very easily by prescription medications.
Anyone with seasonal allergies should consider seeing a doctor if they're worried about their symptoms, if they seem unusual or if they're not relieved by over-the-counter medications.