Oral Allergy SyndromeApril 30, 2018

What is Oral Allergy Syndrome?

There are some fruits and vegetables that have very similar proteins to airborne pollen proteins of certain trees, grasses, and weeds. In people who are allergic to pollen, the body’s immune system sees a similarity between the proteins of the pollen and those of the food, and triggers a reaction called oral allergy syndrome (OAS). For example, up to 50-75% of adults who are allergic to birch tree pollen may experience an itchy mouth or throat after eating an apple or celery. Oral allergy syndrome is also known as pollen fruit syndrome (PFS).

Symptoms of Oral Allergy Syndrome

The most common symptoms of OAS involve itching and/or swelling of the lips, mouth, tongue, and throat area. The symptoms usually appear immediately after eating raw fruits and vegetables, although the reaction can occur more than an hour later. Rarely, in people who are highly allergic, OAS can induce severe throat swelling or even a systemic reaction. OAS does not typically occur in young children. Onset of OAS is more common in older children, teens, and adults. Symptoms are more likely to occur during the spring and fall pollen seasons, but OAS can occur at any time of year. Some people only have symptoms with one food, while others have symptoms with many different fruits and vegetables.


Individuals react to different foods based on what type of seasonal allergies they are affected by. Not all foods associated with a pollen will trigger a reaction. In people allergic to birch tree pollen, some known triggers include apples, pears, peaches, plums, and celery. Those allergic to grasses may have oral allergy symptoms with melons, celery, peaches, and tomatoes. People who have ragweed allergy may experience reactions with bananas, melons, cucumbers, and zucchini. These are just a few of the potential cross-reactions.

Treatment for Oral Allergy Syndrome

If you have symptoms of OAS, avoid eating the foods known to trigger a reaction. After being evaluated by a physician, treatment may include reducing cross-reactions by cooking, baking, or microwaving the food because high temperatures break down the proteins responsible for OAS. This may not be practical for most fruits, however. Eating canned food may also limit the reaction. Peeling the food before eating may also help avoid a reaction, as the offending protein is often concentrated in the skin. It is important to note that none of these treatments should be done without the counsel of a physician. Some people may be prescribed auto-injectable epinephrine that should be available at all times in case of a more serious reaction.  Although there is no specific test for OAS, affected individuals will mostly likely have positive skin or blood tests to specific pollens, in addition to a history of symptoms after ingesting the suspected food(s). Make an appointment to talk with one of our physicians if you are experiencing any of the following:

  • OAS symptoms are getting worse or causing significant throat discomfort
  • Cooked fruits and vegetables are causing OAS symptoms
  • Nuts are causing OAS symptoms (mild mouth symptoms may indicate a more serious allergic reaction to nuts)
  • Symptoms such as hives, vomiting or trouble breathing occur after eating raw fruits or vegetables