beth israel deaconess medical center a harvard medical school teaching hospital

To find a doctor, call 800-667-5356 or click below:

Find a Doctor

Request an Appointment

left banner
right banner
Smaller Larger

Oral Allergy Syndrome

Also Known As Pollen-Food Syndrome

For most people with allergies, springtime arrives with a mix of joy and trepidation. Warmer air means plants and trees are in full bloom and their pollen brings a seemingly endless season of sneezing, wheezing, and itching. For some, symptoms may be further aggravated when consuming certain fruits and vegetables because of a condition call Oral Allergy Syndrome (OAS), also referred to as Pollen-Food Syndrome.

When people who are sensitized to a particular pollen consume fruits and vegetables in the same plant family, their body mistakes one protein for the other.

Most people who develop OAS are allergic to one or more pollens, most commonly birch and ragweed. Allergy-stimulating proteins in plant pollens are similar to proteins in some fruits and vegetables. When people who are sensitized to a particular pollen consume fruits and vegetables in the same plant family, their body mistakes one protein for the other. This protein cross-reaction can cause itching and swelling of the lips, mouth or throat. Most OAS reactions are local and mild, and disappear with a glass of water. In very rare instances, however, asthma or anaphylactic shock may occur.

OAS is not only activated by what you eat, but what you drink as well, including those smoothies made from freshly squeezed or blended fruit and a cup of chamomile tea! Since chamomile and ragweed are in the same plant family, even some soaps, cosmetics, or supplements that contain chamomile may prompt a reaction.


One way to confirm OAS is with a:

  • Skin prick test (SPT) to local pollens and suspected fresh fruits and vegetables
  • Blood tests (RAST)


Once you have a reaction, treatment options may vary.


Although immunotherapy (allergy shots) is not a proven treatment for OAS, some patients who receive immunotherapy for pollen allergy have reported improvement of their OAS.

Antihistamines and Corticosteroid Nasal Sprays

Other treatments may include antihistamines and corticosteroid nasal sprays to alleviate symptoms.

Avoid Uncooked Food

For most people with Oral Allergy Syndrome, however, clearly the best line of defense is a good offense. Avoid the uncooked food in its entirety.The good news is that people with OAS can generally enjoy cooked fruits and vegetables because heat destroys the proteins that cause the allergic reaction. So, try tomatoes sautéed and served over pasta, freshly made applesauce, or homemade banana bread. There is no magic cooking time, but if you make an apple pie and your apples are still crisp, you could have an OAS response. Canned foods do not generally cause OAS. If you suspect you have OAS, experts recommend that you see an allergist and bring a diary of the dates you consumed the fruits and vegetables and the symptoms you experienced.



Birch Pollen Peach, Apple, Plum, Cherry, Apricot, Strawberry, Pear, Almond, Hazelnut, Potato, Carrot and Celery
Grass Pollen Tomato, Melon, and Watermelon
Mugwort (weeds) Apple, Celery, Carrot, Peanut, and Kiwi
Ragweed Pollen Banana, Melon, Honey, Cucumber, Zucchini, Watermelon and Chamomile

Allergic to Latex?

Avoid banana, kiwi, chestnut, avocado, potato, and papaya

Contact Information

Allergy and Inflammation - Research
Department of Medicine
Beth Israel Deaconess Medical Center
Center for Life Science, 9th floor
330 Brookline Avenue
Boston, MA 02215