Oral allergy syndrome, also known as pollen-food syndrome,is caused by cross-reacting allergens found in both pollen and raw fruits, vegetables, or some tree nuts. The immune system recognizes the pollen and similar proteins in the food and directs an allergic response to it. People affected by oral allergy syndrome can usually eat the same fruits or vegetables in cooked form because the proteins are distorted during the heating process, so that the immune system no longer recognizes the food.
Oral allergy syndrome typically does not appear in young children; the onset is more common in older children, teens, and young adults who have been eating the fruits or vegetables in question for years without any problems. Those with oral allergy syndrome typically have allergy to birch, ragweed, or grass pollens.
Although not everyone with a pollen allergy experiences oral allergy syndrome when eating the following foods, they are commonly associated with these allergens:
Symptoms of oral allergy syndrome include itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue, and throat. Itchy ears are sometimes reported. The symptoms are usually confined to one area and do not normally progress beyond the mouth. Because the symptoms usually subside quickly once the fresh fruit or raw vegetable is swallowed or removed from the mouth, treatment is not usually necessary.
Content was based on American College of Allergy, Asthma & Immunology