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If you experience an itchy, tight throat after eating certain raw fruits, nuts, or vegetables, you might assume you have a food allergy. However, it’s possible that you are actually allergic to pollen-like compounds in the food. In other words, your symptoms may be related to an environmental allergy to pollen, rather than a classic food allergy.
When a person reacts to cross-reactive proteins in raw foods, it’s called oral allergy syndrome. This little-known syndrome is relatively uncommon, and although it is bothersome, it’s rarely harmful.
What is oral allergy syndrome?
Oral allergy syndrome, also known as pollen food allergy syndrome, is a set of symptoms caused by an allergic reaction to cross-reactive proteins. Cross-reactive proteins are proteins that trigger an allergic reaction just like pollen. People who experience oral allergy syndrome typically react to specific clusters of foods that correspond to the pollens they are allergic to.
One of the most common symptoms of oral allergy syndrome is an itchy throat or mouth after eating certain foods. Other symptoms include: swelling of the mouth, lips, tongue, or throat, not unlike a food allergy.
What’s the difference between oral allergy syndrome and a food allergy?
The difference between oral allergy syndrome and a food allergy is that the symptoms are localized to the mouth, and are usually not dangerous. While oral allergy syndrome may be unpleasant, it is usually harmless, and it does not progress to anaphylaxis.
Someone who has oral allergy syndrome would test positive for environmental allergies to pollens, yet negative to food allergens. This can be confusing, as people often initially believe they have a food allergy, since food is a trigger.
Generally, oral allergy syndrome is related to the consumption of raw fruits, vegetables, and nuts. Sufferers often find that the cooked version of the food doesn’t cause the same reaction. This is because the allergenic compound has been broken down by the cooking process.
Q&A With Dr Ivor Emanuel, MD
To learn more about oral allergy syndrome, I spoke with Dr. Ivor Emanuel MD, who is a board certified otolaryngology & allergy doctor with over 25 years experience, the director of San Francisco ENT and Allergy Medical Group and part of the imaware™ clinical advisory team.
Q: Is oral allergy syndrome common among people with pollen allergies?
A: “Pollen allergies are common in the US, affecting 20-30% of the population. However, among these people, very few of them will have oral allergy syndrome.”
Q: Which allergies are most commonly associated with oral allergy syndrome?
A: “Oral allergy syndrome is most commonly found in those who have an allergy to birch trees. It’s important to know that in the US, birch tree pollen allergy is not that common. However, birch tree pollen allergy is the most common pollen allergy in Northern Europe. So it could be a bit more common there, and perhaps among people of Northern European descent.”
Q: Should people with pollen allergies be wary of oral allergy syndrome?
A: “People with pollen allergies shouldn’t necessarily be concerned about oral allergy syndrome, unless, of course, they have any of the symptoms.”
Symptoms of oral allergy syndrome include an itchy throat, or swelling in the mouth, lips, tongue, and throat. If you are experiencing these symptoms after eating raw fruits, vegetables, and nuts, it’s a good idea to speak to your allergist.
Q: What are the best ways to manageoral allergy syndrome symptoms?
A: “The best and probably the only way to manage oral allergy syndrome is to not eat the food that triggers the symptoms, at least not raw. … The proteins that cause the reaction are mostly destroyed by cooking, and are also destroyed by stomach acid, which is why they don’t cause trouble in the rest of the body. Fortunately, oral allergy syndrome is usually not dangerous.”
Common trigger foods for pollen allergies
Here are some of the most common trigger foods that contain cross-reactive proteins for certain pollens.
Importantly, you do not have to avoid the food unless you are experiencing symptoms. Even if you have a pollen allergy, you may not react to the proteins in the food.
- Birch pollen: apples, almonds, celery, carrots, peaches, kiwi, cherries, hazelnuts, kiwi, plums, pears
- Grass pollen: celery, peaches, oranges, melons, tomatoes
- Ragweed pollen: cucumbers, melons, bananas, sunflower seeds, zucchini
How to deal with oral allergy syndrome
There are many things you can do to cope with oral allergy syndrome, both in terms of prevention and harm reduction.
Know your triggers
The most important thing you can do as someone who suffers from oral allergy syndrome is to become aware of your trigger foods.
If you notice your throat tingling after that fruit salad you get each morning, it’s something you should pay attention to. A simple food diary plus a symptom log may help you make connections between various ingredients and symptoms.
Avoid trigger foods
Once you’re aware of your trigger foods, it’s important to avoid eating them in the first place, at least in raw form. Elimination is the main recommended treatment for oral allergy syndrome.
Cook trigger foods
People only react to the raw, uncooked version of a food when they have oral allergy syndrome. That means raw celery may be a no-go, while celery cooked into a stew is fine. Experiment with cooking foods that bother you raw, and you may find you can enjoy them again.
Peel foods
If your symptoms are mild, and you enjoy the food, you may find removing the peel reduces your symptoms. This is because many of the cross-reactive compounds are found in or near the peel.
When asked about peeling foods, Dr. Emanuel said: “Peeling the skin may be helpful as the protein is often more concentrated in the skin.”
He added: “Remember, these are broad and general statements, as the allergic response to each food can vary in any individual.”
The bottom line
Oral allergy syndrome is an unpleasant reaction that affects some people who have pollen allergies. It generally doesn’t cause severe symptoms, but in the event you do experience severe symptoms like throat swelling, it’s a good idea to seek medical attention. Oral allergy syndrome is not a food allergy, but it may be confused with one due to shared symptoms.
If you experience an itchy throat or swelling in the mouth area after eating raw fruits, vegetables, or nuts, it could be oral allergy syndrome. It's often possible to deactivate the allergens by thoroughly cooking any fruit and vegetables. In any case, keep a log of your symptoms, and consult your healthcare provider to make sure it’s not a food allergy.
