Oral Allergy Syndrome
Oral Allergy Syndrome


Allergic rhinitis, or hay fever, is a very common condition, affecting 19.2 million adults and 7.7 million children in the U.S., according to the Centers for Disease Control. Some people with hay fever also experience Oral Allergy Syndrome (OAS) an allergic reaction that affects the lips, mouth, and throat. The syndrome is caused by a cross-reaction of allergens that are found in both pollen and raw fruits, vegetables, or some tree nuts, according to the American College of Allergy, Asthma and Immunology. “The immune system recognizes the pollen and similar proteins in the food and directs an allergic response to it. People affected by OAS 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.”(1)

The symptoms of OAS include itchiness and/or swelling of the mouth, face, lip, tongue, and throat. Generally, the symptoms appear right after eating, and are confined to that area of the body, and subside quickly. Rarely, anaphylaxis can develop.(2) Avoiding the foods is the first step in managing OAS, and some allergists may prescribe an epinephrine auto-injector.(1)

Some studies have shown that allergenic immunotherapy (allergy shots) may help with OAS.(2) The American Academy of Allergy, Asthma and Immunology advises that medical attention should be sought if:

  • Your OAS symptoms are causing significant throat discomfort;
  • Your OAS symptoms are getting progressively worse;
  • Your OAS symptoms are caused by cooked fruits and vegetables;
  • Your OAS symptoms are caused by nuts;
  • You develop systemic reactions after eating raw fruits or vegetables such as hives, vomiting or difficulty breathing.(2)

A leading medical center provides this list of potential cross-reactive foods: (Partial list follows)

Pollen: Bananas, melons, zucchini, cucumber
Ragweed: Dandelions, chamomile tea, apples, pears, peaches apricots, cherries, plums, carrots
Birch: Celery, potatoes, peppers, fennel, parsley, coriander, parsnips, hazelnuts, almonds, walnuts
Grass: Peaches, celery, melons, tomatoes, oranges
Mugwort: Celery, apple, kiwi, peanut, fennel
Alder: Celery, pears, apples, almonds, cherries, parsley(3)

(1) American College of Allergy, Asthma and Immunology, Pollen Food Allergy Syndrome, https://www.aaaai.org/

(2) American Academy of Allergy, Asthma and Immunology, Oral Allergy Syndrome, reviewed by Moore, A. M.D., https://www.aaaai.org/

(3) Children’s Hospital of Philadelphia, Oral Allergy Syndrome, https://www.chop.edu/conditions-diseases/

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