Oral Allergy Syndrome

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Published:  December 4, 2023

Many patients with seasonal allergies will also report itching in their mouth when eating certain fruits and vegetables. This is due to a type of food allergy called oral allergy syndrome (or pollen-food allergy syndrome). Oral allergy syndrome is the most common type of food allergy in adults. Up to 76% of people with an allergy to pollen have oral allergy symptoms to at least one fruit or vegetable.

What causes oral allergy syndrome?

Oral allergy syndrome is a localized allergic reaction from ingestion of fruits, vegetables, and nuts that cross-react with a protein in tree, grass, or weed pollen. The protein that causes oral allergy syndrome usually breaks down when heated, so most patients can often tolerate baked or cooked versions of the food like apple pie. This does not occur for tree nuts and peanuts.

Patients will usually develop symptoms of seasonal allergies first (runny or stuffy nose, sneezing, itching) and then develop oral allergy syndrome. However, you can sometimes have oral allergy syndrome without having any symptoms of seasonal allergies. Oral allergy syndrome can develop at any age.

What are the main symptoms?

  • Itching and tingling of the mouth
  • Mild swelling of lips
  • Up to 10% of patients may develop more severe symptoms (including hives, nausea, wheezing)
  • Symptoms usually occur within minutes of eating fruits or vegetables
  • Symptoms can increase during or after pollen season

How do we diagnose oral allergy syndrome?

  • Patient history
  • Skin prick testing to the foods that cause symptoms and skin prick testing to pollens
  • “Component testing” to peanuts and tree nuts on laboratory testing

What is the management of oral allergy syndrome?

  • Avoidance of raw fruits and vegetables or any form that causes symptoms
  • Epinephrine auto-injectors are rarely needed but may be prescribed for patients with severe symptoms or increased risk of systemic symptoms
  • There are case reports that demonstrate allergen immunotherapy (“allergy shots”) to pollens results in increased tolerance to the fresh fruits and vegetables that cause oral allergy syndrome

If you have any questions about oral allergy syndrome, please call our office or schedule an appointment online.