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Overview

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.

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Triggers

Although not everyone with a pollen allergy experiences oral allergy syndrome when eating the following foods, they are 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

Symptoms

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.

Diagnosis

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

If you or your child experience a reaction beyond the mouth area after eating a fresh fruit or raw vegetable, that food could be considered a risk for anaphylaxis, a serious reaction that is rapid in onset and may cause death. In one study, researchers found that oral allergy syndrome symptoms may progress to systemic symptoms in nearly 9 percent of patients and to anaphylactic shock in 1.7 percent of patients. Consult with your allergist for more information and to determine whether you should carry an epinephrine auto-injector to treat such potential severe reactions.