Overcome Oral Allergy Syndrome!

Oral Allergy Syndrome Foods, Symptoms & How To Treat It

Do you have oral allergy syndrome? Learn more about trigger foods, symptoms, and how you can manage it from a board-certified food allergist in St. Louis, Missouri. Dr. Sonia Cajigal is here to help. Schedule your visit today! “Dr. Cajigal was friendly, professional, and informative. She took the time to explain the tests and what was going on with my allergies. She is so knowledgeable and really cared about how I was feeling. I would highly recommend this practice if you suffer from allergies and asthma.” – Sue D, July 2020
Oral Allergy Syndrome Doctor Sonia Cajigal of St. Louis Family Allergy in St. Louis, Missouri
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What is Oral Allergy Syndrome?

Oral Allergy Syndrome Foods
Oral Allergy Syndrome Symptoms
Oral Allergy Syndrome Treatment
Oral allergy syndrome (OAS), also known as pollen fruit syndrome (PFS), is a condition in which individuals with seasonal pollen allergies also react to certain raw vegetables, uncooked fruits, nuts, and spices. As an example, if you have a birch pollen allergy, you may also have an allergic reaction to peaches, apples, pears, and other foods. Oral allergy syndrome occurs when your immune system recognizes a protein in a fruit, vegetable, nut, or spice as a pollen that you’re allergic to. This phenomenon is often referred to as ‘cross-reactivity,’ and is not the same as being allergic to a food. For example, most of our patients who have allergic reactions to honeydew, watermelon, and cantaloupe actually have a weed-pollen allergy. Pineapple is another fruit where food allergy is possible, but allergic reactions can also be caused by cross-reactivity with birch tree pollen. Importantly, eggs, seafood, and cow’s milk are non-plant foods, and do not contain proteins that resemble pollens. Therefore, these food categories do not cause oral allergy syndrome.

Common Food Allergens

The most common food allergies are:

  • Peanuts
  • Wheat
  • Soy
  • Cow’s Milk
  • Eggs
  • Fish
  • Shellfish
  • Tree Nuts
  • Sesame

Sometimes other allergies, such as pollen allergies, can appear as food allergies because foods contain proteins that are similar to the thing that you’re actually allergic to. For example, if you are allergic to birch tree pollen, you may have reactions triggered by peaches, pears, kiwi, cherries, apples, plum, coriander, parsley, fennel, celery, and carrots. This is called oral allergy syndrome (OAS), also known as pollen fruit syndrome (PFS).

Every case of food allergies is unique and nuanced, which is why it’s important to get tested and get to the bottom of what you’re allergic to. A food allergy reaction can be life-threatening, so individuals with food allergies must be very aware of exposure and be very careful to avoid food triggers. It is also possible that you or your child’s reaction to a certain food is actually an intolerance and not an allergy, though the symptoms can be similar. In either case, proper testing by an allergist is the only way to know for sure what you’re dealing with and how to most effectively navigate it. If you suspect a food allergy and wondering how to get tested for food allergies, contact us today to discuss your concerns!

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Common oral allergy syndrome foods and food allergens

Oral Allergy Syndrome Foods

Several foods can trigger oral allergy syndrome. We’ve listed some of the most common oral allergy syndrome foods here as well as the culprit allergen(s) for each food.

Oral Allergy Syndrome Fruits

  • Apples (Birch Tree)
  • Apricots (Birch Tree)
  • Bananas (Ragweed)
  • Cantaloupe (Ragweed)
  • Cherries (Birch Tree)
  • Grapes (Mugwort Weed)
  • Honeydew (Ragweed)
  • Kiwi (Ragweed)
  • Peaches (Birch Tree)
  • Pineapple (Birch Tree)
  • Plums (Birch Tree)
  • Mangos (Mugwort Weed)
  • Melons (Grass)
  • Oranges (Grass)
  • Tomatoes (Grass)
  • Watermelon (Ragweed)

Oral Allergy Syndrome Vegetables

  • Bell Pepper (Mugwort Weed)
  • Black Pepper (Mugwort Weed)
  • Carrot (Birch Tree, Mugwort Weed)
  • Celery (Birch Tree. Mugwort Weed)
  • Cucumber (Ragweed)
  • Garlic (Mugwort Weed)
  • Onion (Mugwort Weed)
  • Parsley (Birch Tree)
  • Swiss Chard (Grass)
  • Zucchini (Ragweed)

Oral Allergy Syndrome Nuts

  • Almonds (Birch Tree)
  • Hazelnuts (Birch Tree)
  • Peanuts (Birch Tree, Grass)
  • Soybeans (Birch Tree)

Oral Allergy Syndrome Spices

  • Aniseed (Birch Tree, Mugwort Weed)
  • Caraway (Birch Tree, Mugwort Weed)
  • Coriander (Birch Tree, Mugwort Weed)
  • Fennel (Birch Tree, Mugwort Weed)
  • Paprika (Mugwort Weed)
This list is by no means exhaustive. Consult your allergist to learn for certain if you have a food allergy or if your food reactions are actually caused by oral allergy syndrome.
See an OAS Doctor

in St. Louis, Missouri

Woman reacting to oral allergy syndrome foods scratching rash on her neck

Oral Allergy Syndrome Symptoms

Common OAS symptoms include:
  • Itchiness of the mouth and throat
  • Tingling of the lips, mouth, or throat
  • Slight swelling and bumps on the mouth or lips
Less common OAS symptoms include:
  • Itching, redness, or slight swelling of the hands if they are used to handle or peel raw fruits or vegetables
  • Nausea or stomach upset
  • Throat tightness, chest tightness, or difficulty breathing
OAS symptoms are typically isolated to the mouth or the throat, but they can also cause more severe symptoms in rare cases, including anaphylaxis. Symptoms often begin a few minutes after eating the problematic food, but usually subside once the food has been swallowed and the reactive proteins are destroyed by saliva and stomach acid. OAS symptoms can also vary in severity depending on current pollen conditions and other factors. They are most severe during pollen season and for a few months after. Eating a very large amount of a reactive food, exercising intensely after eating, and drinking alcohol can cause more severe symptoms. Illness and certain medications can also worsen symptoms.

How To Treat Oral Allergy Syndrome

Many are surprised to learn that oral allergy syndrome can sometimes be prevented with a little food preparation. Oral allergy syndrome symptoms are often caused by direct contact with a particular protein, so taking steps to remove or alter that protein can drastically lessen the effects of oral allergy syndrome or eliminate reactions altogether. Here are some tips to help you manage oral allergy syndrome.
  • Peel the skin off of fruits and vegetables – Proteins that trigger oral allergy syndrome can sometimes reside exclusively in the skin, so removing it can prevent allergic reactions.
  • Heat fruits and vegetables before eating – Heating certain foods can deactivate proteins such that they do not trigger oral allergy syndrome.
  • Canned fruits and vegetables are usually okay to eat as well because they’ve been processed.
  • Avoid dehydrated fruits, as they typically aren’t cooked before drying.
  • Avoid foods that trigger your oral allergy syndrome altogether. This is the most assured way to prevent oral allergy syndrome.
  • H1 antihistamines – If you’ve been exposed to a food that has triggered your oral allergy syndrome, H1 antihistamines like Claritin, Zyrtec, and Benadryl can help reduce symptoms of OAS once they do occur.
  • Avoid pre-medicating – Pre-medicating with an oral antihistamine in order to tolerate eating a problematic food is generally not recommended by allergists. This is especially true for patients who experience systemic symptoms beyond mild mouth or throat discomfort and for those who have reactions to high-risk foods including certain nuts.
  • Carry an Epi-Pen – Some patients can experience severe symptoms with OAS that do not resolve quickly. In these cases, it is best to carry an epinephrine autoinjector (Epi-Pen) for injecting epinephrine when a severe allergic reaction occurs.
Of course, the first step to managing your oral allergy syndrome is to learn exactly what you’re allergic to and what is triggering your symptoms. Visit us at St. Louis Family Allergy to get to the bottom of your symptoms and learn personalized strategies to manage your allergies. We look forward to your visit!


[1] American College of Allergy, Asthma & Immunology: https://acaai.org/ [2] Asthma and Allergy Foundation of America: https://www.aafa.org/
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"Dr. Cajigal was friendly, professional, and informative. She took the time to explain the tests and what was going on with my allergies. She is so knowledgeable and really cared about how I was feeling. I would highly recommend this practice if you suffer from allergies and asthma."

- Sue D, July 2020

“Dr Cajigal is a great listener. She trusts her patients instead of treating them as if they are not the experts of their own bodies. I really appreciate that (many doctors do not have that quality). She also immediately treats the symptoms instead of waiting to see if things clear. I use her for my children and myself. We have never left her office feeling as if it was a waste of time.”

– Stephanie, August 2020

"Great Allergist!"

- Ann H, December 2018

"She is the best."

- Stephen W, June 2020

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