Pollen Food Allergy Syndrome (PFAS), also known as oral allergy 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 PFAS can usually eat the same fruits or vegetables in cooked form because the proteins are distorted during the heating process, and the immune system no longer recognizes the food.
PFAS typically does not appear in young children. The arrival 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. Young children under the age of 3 do not usually develop allergic rhinitis (hay fever) until after they are toddlers. Hay fever is associated with reactions to the pollens that cross-react with the foods Those with PFAS typically have allergy to birch, ragweed, or grass pollens.
Speak to an Allergist.
If you’re always getting an itchy mouth after eating the same raw fruit or vegetable, see an allergist for diagnosis and treatment.
Although not everyone with a pollen allergy experiences PFAS 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 of PFAS include itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue, and throat. Itchy ears and hives on the mouth are sometimes reported. The symptoms are usually confined to one area and do not normally progress beyond the mouth, It is rare that a patient would develop symptoms away from the mouth, or anaphylaxis from this, although it has been reported in a very small percentage of patients. 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 of PFAS is made 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 comes on quickly and may cause death. In one study, researchers found that PFAS progressed 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 potential severe reactions.
Avoiding the food in raw forms is the most common way to manage this. If a food cannot be eaten in cooked form, e.g., melons, you might choose to avoid eating those foods if they cause intolerable symptoms. If you experience significant throat discomfort or difficulty swallowing, or have systemic symptoms, reactions to cooked forms of the foods, or symptoms to high-risk foods such as peanut or tree nuts, your allergist may prescribe an epinephrine auto-injector.
This page was reviewed for accuracy 3/21/2019.