Oral Allergy Syndrome

What is oral allergy syndrome?

Oral allergy syndrome, also known as pollen-food syndrome, results from cross-reacting allergens found in both pollen and raw fruits, vegetables, or some tree nuts. The immune system detects the pollen and similar proteins in the food and directs an allergic response to it. People affected by oral allergy syndrome often can eat the same fruits or vegetables in cooked form without an adverse reaction. The reason is that the proteins change enough during the heating process, so that the immune system no longer senses the problematic proteins in the food.

The onset is more common in older children, teens, and young adults who have been eating the fruits or vegetables and hadn't experienced any ill effects. Normally an allergy to birch, ragweed, or grass pollens accompanies oral allergy syndrome.

Although most with a pollen allergy do not experience oral allergy syndrome when eating the following foods, oral allergy syndrome is commonly associated with these allergens:

• Birch pollen: apple, almond, carrot, celery, cherry, hazelnut, kiwi, peach, pear, plum
• Grass pollen: celery, melons, oranges, peaches, tomato
• Ragweed pollen: banana, cucumber, melons, sunflower seeds, zucchini

What are the symptoms of oral allergy syndrome?

Symptoms of oral allergy syndrome often occur on the mucus membranes of the mouth and throat. It can include itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue, and throat. Itchy ears are sometimes reported.

The symptoms do not normally spread beyond the mouth. Because the symptoms usually diminish quickly once the fresh fruit or raw vegetable is swallowed or removed from the mouth, treatment is not usually necessary.

Diagnosis of oral allergy syndrome is ascertained by taking a patient’s clinical history and, in some cases, conducting skin prick tests and oral food challenges with raw fruit or vegetables.

What is the treatment for oral allergy syndrome?

After we identify your child's allergen, a specialist from the Pediatric Food Allergy Program will help you understand how to avoid it.

If the reaction expands beyond the mouth area after eating a fresh fruit or raw vegetable, that food may be a risk for anaphylaxis, a life-threatening reaction that is rapid in onset. Our pediatric allergists can provide more information and determine whether you should carry an epinephrine auto-injector to treat severe reactions.