Could Your Child Have Oral Allergy Syndrome?

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You don't know what to do. Every time, your child takes a bite of apple or celery they complain that it makes their throat scratchy or itchy.

You wonder if they could have a food allergy and watch for telltale signs like hives, swollen lips, or even difficulty breathing, and yet, the mysterious reaction never goes any further than a few complaints about itchiness. Is it that your child just doesn't like apples and celery, or could something else be going on?

According to Kara J. Wada, MD, clinical assistant professor in the division of allergy immunology department of otolaryngology at The Ohio State University Medical Center, it could be that your child has oral allergy syndrome (OAS), especially if they have seasonal allergies like hayfever or allergic rhinitis.

In fact, experiencing an itchy mouth or throat after eating apple or celery happens in 50 to 75% of people allergic to birch pollen. The reason for this is that the proteins found in some fruits and vegetables are very similar to those found in pollen like birch.

Consequently, these proteins trick the immune system and cause an allergic reaction or make existing allergy symptoms worse. Here's what you need to know about oral allergy syndrome, including how it's diagnosed and how it's treated.

What Is Oral Allergy Syndrome?

According to the American Academy of Allergy, Asthma, and Immunology (AAAAI) OAS, or pollen food allergy syndrome as it's sometimes called, is a type of contact allergic reaction that occurs when the mouth and throat come in contact with certain raw fruits and vegetables or some tree nuts. The immune system recognizes similar proteins and responds with an allergic reaction.

People who have OAS often experience an itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue, and throat. Sometimes kids with oral allergy syndrome will even have itchy ears or hives around their mouth.

Interestingly, people affected by OAS can often eat the offending foods in cooked form. Heat changes the proteins, so the immune system often doesn't recognize the food.

Overall, kids tend to react to different foods based on what type of seasonal allergies they have. For instance, children with allergies to grasses may find that they react to celery, tomatoes, peaches, melons, and oranges.

Symptoms of Oral Allergy Syndrome

The most common symptoms of OAS include itchiness or swelling of the mouth, face, lips, tongue, and throat. Symptoms usually show up immediately after eating raw fruits and vegetables. However, in rare cases, the symptoms can appear more than an hour after eating.

David Stukus, MD

Oral allergy syndrome occurs in both children and adults who have environmental allergies.

— David Stukus, MD

"The symptoms occur due to cross-reactivity with similar proteins in fresh fruits and vegetables," says David Stukus, MD, professor of clinical pediatrics in the division of allergy and immunology at Nationwide Children's Hospital. "What's more, the symptoms are almost always subjective and confined to the mouth and throat. On very rare occasions, people will experience rashes, throat tightening, and even anaphylaxis."

Food Allergies and OAS

Parents need to understand that there is a very important difference between true food allergies and oral allergy syndrome, says Dr. Stukus. Many times patients can eat the offending foods when they have OAS, especially if they try different preparations.

This is not the case with a food allergy. With food allergies, the offending food—like milk, eggs, soy, wheat, fish, shellfish, peanuts, and tree nuts—must be avoided at all times due to the high risk of anaphylaxis. Likewise, people with food allergies usually carry an EpiPen.

According to Dr. Stukus, there is no direct correlation between true food allergies and oral allergy syndrome. Additionally, he notes that children usually don't develop oral allergy syndrome until they are older or even into adolescence.

"Seasonal allergies usually don't develop until 3 or 4 years of age," he says. So, OAS doesn't usually show up until they have developed allergies to pollens and then typically only occurs in very allergic individuals.

When to Call a Doctor

If you suspect your child has oral allergy syndrome, or if you are concerned that they have a food allergy, contact your healthcare provider. They can help you identify what is going and refer you to a specialist. If you feel that your child is in immediate danger, do not hesitate to call 911 or take your child to the nearest emergency room.

Diagnosis of Oral Allergy Syndrome

Most of the time, a diagnosis of oral allergy syndrome is made by reviewing the patient's medical history and allergic reactions. For instance, kids with oral allergy syndrome usually are diagnosed with seasonal allergies first and then, later develop oral allergy syndrome—sometimes years after eating the offending food or foods without any issues.

Sometimes, an allergist will perform a skin prick test as well as blood tests to help confirm the diagnosis, but it's important to note that oral allergy syndrome must be handled on a case-by-case basis. No two kids will respond in the same way or react to the same foods, says Dr. Stukus.

"Typically, patients will develop allergic rhinitis symptoms to pollen before the onset of oral allergy symptoms," says Dr. Wada. "Medications used to treat allergy symptoms are not very helpful for preventing the symptoms of oral allergy syndrome, but there are some patients who will see improvement with the use of immunotherapy."

Potential Cross-Reactive Foods
Pollen Potential Cross-Reactive Foods
Ragweed  Bananas, Zucchini, Cucumber, Dandelions, Chamomile Tea, Melons (Watermelon, Cantaloupe, Honeydew) 
Birch  Apples, Pears, Peaches, Apricots, Cherries, Plums, Nectarines, Prunes, Kiwi, Carrots, Celery, Potatoes, Peppers, Fennel, Parsley, Coriander, Parsnips, Hazelnuts, Almonds, Walnuts 
Grass  Celery, Tomatoes, Peaches, Melons, Oranges 
Mugwort  Celery, Apples, Kiwi, Peanut, Fennel, Carrots, Parsley, Coriander, Sunflower, Peppers 
Alder  Celery, Pears, Apples, Almonds, Cherries, Hazelnuts, Peaches, Parsley 
Latex Bananas, Avocado, Kiwi, Chestnut, Papaya
According to Dr. Wada, there are certain foods that tend to cross-react with pollens. However, OAS is unique to each person and not everyone reacts to the same foods.

"If parents notice their child having mouth itching related to particular foods, they should consider discussing their child's symptoms with their physician," says Dr. Wada. "They also should take note of any rashes, stomach upset, vomiting, or trouble breathing associated with localized symptoms. And if there are additional symptoms [aside from the mouth itchiness], they should consider getting emergency care."

Treatment of Oral Allergy Syndrome

Dr. Stukus indicates that although oral allergy syndrome is relatively common, parents can minimize their child's symptoms by peeling and cooking fruits and vegetables that lend themselves to that type of preparation.

"There are a lot of different fruits and vegetables that fall under each pollen," he explains. "We usually don't tell people to avoid food, especially if they can find other ways to eat the foods. Sometimes if you process food in some way—such as cooking it, heating it, or peeling it—parents will find that their child can eat it. Proteins are very labile and can be destroyed easily. Even saliva is very good at breaking down the proteins in the food."

What's more, OAS tends to be worse during the pollen season. So, if your child is allergic to birch, which typically creates symptoms in spring, they may experience more challenges eating certain foods during spring but experience little to no symptoms in the winter.

Parents also worry that their child's OAS may progress into something more serious. But the majority of the time, there is nothing to worry about.

Kara J. Wada, MD

There is less than a 2% chance of anaphylaxis with oral allergy syndrome.

— Kara J. Wada, MD

"However, the risk increases if a large amount of the offending food is ingested on an empty stomach, being on acid-blocking medications, and having other co-factors present [like recent exercise or use of NSAID medications, which increase the permeability of the gut]," says Dr. Wada.

A Word From Verywell

At first, it may seem odd that your child would complain that fresh fruits and vegetables are causing them discomfort like an itchy throat, especially if no other signs of an allergic reaction occur. You may even wonder if it's really just a matter of them not wanting to eat their vegetables. But OAS is a very real condition.

If your child is regularly complaining that foods are causing them discomfort, pay attention. Write down the foods and their symptoms and share them with your healthcare provider. Together, you can determine what is wrong and if your child does, in fact, have OAS.

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  1. American Academy of Allergy, Asthma, and Immunology. Oral allergy syndrome. Updated September 28, 2020.

  2. American Academy of Allergy, Asthma, and Immunology. Pollen food allergy syndrome. Updated March 21, 2019.

Additional Reading
  • Sussman G, Sussman A, Sussman D. Oral allergy syndromeCMAJ. 2010;182(11):1210-1211. doi:10.1503/cmaj.090314