How to Treat Oral Allergy Syndrome

Oral Allergy Syndrome, or OAS, is a type of a contact allergic reaction that happens when the mouth and throat of certain persons contact raw or uncooked fruits or vegetables at any time of the year. People who are allergic to pollens may react upon eating certain raw foods because proteins in those foods can be similar to or identical to proteins found in certain fruits and vegetables. Symptoms of OAS, which usually occur immediately after eating raw fruits and vegetables, include itchiness and/or swelling of the mouth, face, lips, tongue, and throat. OAS is generally a mild food allergy, but in rare cases cause severe throat swelling that lead to difficulty swallowing or breathing. Symptoms usually go away as soon as you stop eating the food and don’t generally require treatment.[1] You can prevent OAS by eliminating trigger foods from your diet and you can relieve symptoms with medical help.

Part 1
Part 1 of 2:

Eliminating OAS-Trigger Foods

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    See your doctor. If you suspect you may have oral allergy syndrome, it’s important to see your doctor. Medical professionals can help identify your specific oral allergy and make suggestions on what types of raw fruits and vegetables to eliminate. Your doctor may even suggest seeing an allergist or immunologist to pinpoint specific oral allergies.[2]
    • Let your doctor know what foods cause a reaction when you eat them. This may be things such as apples, kiwis, peppers, or almonds.
    • Make sure the doctor knows what types of symptoms you experience, especially if they are severe. Your doctor may suggest taking anti-histamines or carrying an epinephrine injection to relieve symptoms, depending on severity.
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    Identify cross-reactive foods. OAS symptoms occur because of your mouth reacting to a certain substance in raw foods and vegetables. Certain pollens you may be allergic to also have cross-reactive foods. Knowing what raw fruits and vegetables may inflame OAS can help you avoid them and prevent a reaction. The following is a list of pollens and their cross-reactive fruits and vegetables:[3]
    • Ragweed: bananas, melons, zucchini, cucumber, dandelion, chamomile
    • Birch: apples, pears, peaches, apricots, cherries, plums, nectarines, prunes, kiwi, carrots, celery, potatoes, peppers, fennel, parsley, coriander, parsnips, hazelnuts, almonds, walnuts
    • Grass: peaches, celery, melons, tomatoes, oranges
    • Mugwort: celery, apple, kiwi, peanut, fennel, carrots, parsley, coriander, sunflower, peppers
    • Alder: celery, pears, apples, almonds, cherries, hazelnuts, peaches, parsley
    • Latex: bananas, avocado, kiwi, chestnut, papaya
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    Read product labels.[4] In some cases, cross-reactive fruits and vegetables that are packaged may also cause OAS symptoms. Reading the labels on packaged foods for cross-reactive substances, such as sunflower or celery, can prevent a bout of OAS.
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    Limit exposure to cross-reactive foods in your kitchen. Avoiding cross-reactive foods is the best way to treat your OAS. Getting rid of or limiting exposure to potentially cross-reactive foods can minimize your risk for an allergic reaction.[5]
    • Avoid using raw fruits and vegetables that are cross-reactive. Consider not keeping them in your kitchen to minimize your risk of eating them.
    • Store cross-reactive foods in a place where you aren’t exposed to them.
    • Stock alternatives to raw fruits and vegetables that cause OAS symptoms. For example, if you have a grass allergy and like peaches, consider plums or apples instead.
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    Peel skin from cross-reactive foods. The protein that causes OAS symptoms is often concentrated in the skin of the fruits or vegetables. Peeling off the skin may help to reduce or prevent OAS symptoms.[6]
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    Cook cross-reactive fruits and vegetables. High temperatures break down the proteins that can cause OAS. Try cooking the cross-reactive fruits and vegetables to reduce or prevent OAS symptoms.[7]
    • Place the cross-reactive food either in the oven or a microwave. Both will break down the proteins that cause OAS. Try eating them after cooking to see if you still have OAS symptoms.
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    Remove or swallow the cross-reactive substance. In most cases, your OAS symptoms will go away once you swallow the cross-reactive fruit or vegetable. You can also remove it from your mouth. Both methods can minimize and relieve your OAS symptoms.[8]
    • Avoid swallowing any cross-reactant if you experience trouble breathing, tightness in your throat, nausea, dizziness, rapid heartbeat, or fainting. These are signs of a serious allergic reaction called anaphylaxis. Remove the cross-reactant and seek immediate medical attention if you experience any of these symptoms.[9]
    • Also avoid swallowing cross-reactant food if you have a history of eosinophilic esophagitis (EoE), so that you can minimize the exposure of the problematic food to your esophagus.
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    Navigate restaurant visits. Having OAS can make it difficult to eat out. Many places prepare dishes with raw fruits and vegetables or on surfaces exposed to the allergens. Call ahead and ask questions about the menu and preparation to minimize your risk of an OAS bout.[10]
    • Ask the manager, server, or cook to accommodate your OAS when possible. Explaining your triggers can help.
    • Make a second, safe choice if you can’t get your first without cross-reactive substances.
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Part 2
Part 2 of 2:

Using Medical Treatments

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    Recognize OAS symptoms. Although most often confined to the facial area, OAS can come with a host of symptoms. Recognizing symptoms may help you more quickly identify and treat a reaction. Symptoms of OAS may include:[11]
    • Itchy mouth
    • Scratchy throat
    • Swelling of the ears, lips, tongue, and throat
    • Itchy ears
    • Irritation of the gums, eyes, or nose[12]
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    Take an antihistamine. In some cases, removing or swallowing a food won’t relieve your OAS symptoms. If this happens, take an over-the-counter antihistamine. This can block the reaction caused by the allergen and relieve your symptoms.[13] Over-the-counter antihistamines you can try include:[14]
    • Loratadine (Claritin, Alavert)
    • Cetirizine (Zyrtec Allergy)
    • Fexofenadine (Allegra Allergy)
    • Levocetirizine (Xyzal), a relatively new medication.[15]
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    Seek medical treatment. If your OAS isn’t relieved by home measures or is getting worse, make an appointment with your doctor. An exam can identify specific allergens and cross-reactive fruits and vegetables. Your doctor can also help formulate a plan to relieve your OAS symptoms.[16]
    • Let your doctor know about any specific symptoms you’re experiencing and ways you have tried to relieve them. You should also tell your doctor if your OAS symptoms are caused by nuts or cooked fruits and vegetables.
    • Ask your doctor if there is any medication or measures that may help you. Make sure to take any medication she suggests or prescribes.[17]
    • Seek emergency treatment if you develop any signs or symptoms of a severe OAS reaction including constriction of airways that makes it difficult to breathe, shock with a severe drop in blood pressure, rapid pulse, dizziness or lightheadedness.
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    Consider allergy shots. If you have recurrent or severe OAS, getting allergy shots may help control and prevent symptoms. Consult with your doctor about using allergen immunotherapy, or allergy shots, for your OAS.[18]
    • Recognize that it may take up to a year to see the full benefits of allergy shots. Maintenance may require monthly injections for five to seven years.[19]
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    Carry an epinephrine auto-injector. Some individuals have severe and recurrent OAS symptoms. Others may have gone into anaphylactic shock because of a cross-reactant. If you fall into either category, consider carrying an epinephrine auto-injector to treat potential severe reactions.[20] Discuss getting a prescription for an epinephrine auto-injector with your doctor.[21]
    • Use this medication only as directed by your doctor. The medication also comes with patient instructions that you should read and follow.
    • Make sure that you and your family know how to properly use the auto-injector. Proper administration of the medication is injecting it only into the muscle or subcutaneous fat of your outer thigh. Injecting into your buttock or a vein can cause serious side effects.
    • Carry two auto-injectors with you at all times to minimize the risk of a serious OAS reaction.
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Warnings

  • Seek immediate medical attention if you are having a severe allergic reaction to a raw fruit or vegetable.
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References

  1. ↑ http://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome
  2. ↑ https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/oral-allergy-syndrome-(oas)
  3. ↑ http://www.chop.edu/conditions-diseases/oral-allergy-syndrome-oas
  4. ↑ https://foodallergycanada.ca/living-with-allergies/day-to-day-management/reading-food-labels/
  5. ↑ http://www.chop.edu/conditions-diseases/oral-allergy-syndrome-oas
  6. ↑ http://www.chop.edu/conditions-diseases/oral-allergy-syndrome-oas
  7. ↑ https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/oral-allergy-syndrome-(oas)
  8. ↑ http://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome
  9. ↑ http://acaai.org/allergies/anaphylaxis
  1. ↑ https://www.foodallergy.org/resources/calling-restaurants
  2. ↑ http://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome
  3. ↑ http://www.chop.edu/conditions-diseases/oral-allergy-syndrome-oas
  4. ↑ http://www.chop.edu/conditions-diseases/oral-allergy-syndrome-oas
  5. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4655061/
  6. ↑ https://medlineplus.gov/druginfo/meds/a607056.html
  7. ↑ https://acaai.org/allergies/allergic-conditions/food/pollen-food-allergy-syndrome/
  8. ↑ https://www.nhs.uk/conditions/food-allergy/treatment/
  9. ↑ https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/oral-allergy-syndrome-(oas)
  10. ↑ http://www.chop.edu/treatments/allergy-shots-immunotherapy
  11. ↑ http://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome
  12. ↑ https://www.nhs.uk/conditions/food-allergy/treatment/

About This Article

Sarah Gehrke, RN, MS
Medically reviewed by:
Sarah Gehrke, RN, MS
Registered Nurse
This article was medically reviewed by Sarah Gehrke, RN, MS. Sarah Gehrke is a Registered Nurse and Licensed Massage Therapist in Texas. Sarah has over 10 years of experience teaching and practicing phlebotomy and intravenous (IV) therapy using physical, psychological, and emotional support. She received her Massage Therapist License from the Amarillo Massage Therapy Institute in 2008 and a M.S. in Nursing from the University of Phoenix in 2013. This article has been viewed 14,840 times.
10 votes - 90%
Co-authors: 8
Updated: August 3, 2022
Views: 14,840
Categories: Food Allergies

Medical Disclaimer

The content of this article is not intended to be a substitute for professional medical advice, examination, diagnosis, or treatment. You should always contact your doctor or other qualified healthcare professional before starting, changing, or stopping any kind of health treatment.

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