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    Oral Allergy Syndrome (OAS)

    Updated at February 17th, 2022

    Definition

    • A minor allergic reaction to some raw fruits and vegetables
    • Causes itching and swelling only to the lips and tongue
    • Also called Pollen-Food Syndrome

    Health Information

    Symptoms

    • Rapid onset of itching (or tingling) and swelling of the mouth.
    • This includes the lips, tongue, throat, and roof of the mouth.
    • The uvula (tag of tissue hanging down in back) can become very swollen.
    • The reaction follows eating a high risk raw fruit or vegetable.
    • Oral Allergy Syndrome (OAS) can start by age 5.
    • Severe reactions and serious symptoms rarely happen.

    Causes

    • A contact allergy. It is limited to the parts of the mouth that touch the raw food.
    • Trigger foods for OAS are always raw and uncooked.
    • Fresh Fruits. Includes apple, apricot, banana, cherry, melons, orange, peach and pear
    • Raw Vegetables. Includes carrot, celery, parsley, potato and tomato. Carrots and celery have the highest risk for also causing serious symptoms.
    • Certain Seeds. Includes sunflower seeds and fennel seeds

    Oral Allergy Syndrome and Nose Allergies Can Be Linked

    • Over 50% of people who are allergic to pollen also have OAS. This means 10% of all people.
    • Ragweed pollen allergy can cross-react with all melons. Also, sometimes with bananas and tomatoes.
    • Birch pollen allergy can cross-react with raw potatoes, carrots, celery and apples.
    • Grass pollen allergy can cross-react with tomato and kiwi.

    Care Advice

    1. Overview:
      • Oral Allergy Syndrome (OAS) is very common. It happens in 10% of people. Most of them also have pollen allergies.
      • The symptoms are not harmful and can be treated at home.
      • Required for OAS: Your child has never had any serious symptoms with this food.
      • OAS symptoms don’t last very long.
      • Here is some care advice that should help.
    2. Rinse the Mouth:
      • Rinse the lips and mouth with warm water. Do this a few times.
      • Reason: To remove any traces of the food.
    3. Cold Pack:
      • Use ice or a cold pack to the swelling lips or tongue for 10 minutes.
      • Reason: To lessen the swelling and the itch.
    4. Benadryl:
      • One dose of Benadryl may help the symptoms go away faster.
      • No prescription is needed.
      • If you only have other allergy meds at home (but not Benadryl), use that.
    5. Prevention of Future OAS:
      • Keep a list of the foods that cause your child’s symptoms.
      • Avoid these foods if they are raw (fresh).
      • The cooked version of these foods usually won’t cause any symptoms.
    6. What to Expect:
      • With or without treatment, the itching will go away in 1 to 2 hours.
      • The mouth swelling will also go away quickly.

    Call Your Doctor If

    • Trouble swallowing or drooling occurs
    • Trouble breathing occurs
    • Swelling or rash occurs elsewhere
    • You think your child needs to be seen
    • Your child becomes worse

    Author: Barton Schmitt MD, FAAP

    Copyright 2000-2020 Schmitt Pediatric Guidelines LLC

    Disclaimer: This health information is for educational purposes only. You the reader assume full responsibility for how you choose to use it. The information contained in this handout should not be used as a substitute for the medical care and advice of your pediatrician. Listing of any resources does not imply an endorsement.

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