Pollen Food Allergy Syndrome (PFAS)

Also: Oral Allergy Syndrome

Adapted from the American College of Allergy, Asthma & Immunology (www.ACAAI.org):

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, but usually begins 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.


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, dandelions, chamomile tea
  • Mugwort: celery, apple, kiwi, peanut, fennel, carrot, parsley, coriander, sunflower, peppers.
  • Latex: banana, avocado, kiwi, chestnut, papaya.
  • Alder: celery, pear, apple, almond, cherry, hazelnut, peach, parsley


Symptoms of PFAS include itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue, and throat. Less common are itchy ears and hives around the mouth. Anaphylaxis (vomiting, wheezing, mouth swelling, along with hives) is rare unlike IgE mediated food allergies.


Typically symptoms are short-lived, but antihistamines can be useful for more prolonged mouth itchiness or discomfort.


Diagnosis of PFAS is determined by clinical history and, in some cases, conducting skin prick tests and oral food challenges with raw fruit or vegetables.

If your child experiences 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. 


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, avoid eating those foods if they cause intolerable symptoms. If your child has more extensive reactions we will have your child completely avoid those foods in raw form, refer to an allergist, and likely prescribe an epi-pen to carry in the event of a systemic reaction.