If your mouth itches when you eat fruit, pollen may be the culprit

My mouth sometimes itches when I eat raw apples, peaches or cherries. It is so annoying that I often avoid those fruits. Strangely, cherry pie never gives me a problem.

I now understand the tasty mystery of the cherry pie.

I suffer from hay fever and, like many others, I have developed what is known as oral allergy syndrome (sometimes called pollen food allergy syndrome). A usually harmless allergy, it occurs because I'm sensitive to pollen and I also react to raw fruits and vegetables that have proteins similar to those in pollen. The result: itchiness in the mouth and throat.

Luckily, cooking the produce makes the problem go away, so cherry pie doesn't set off symptoms.

Pollen in trees, grass and weeds contains proteins that cause the itchy, drippy, sneezy symptoms of hay fever or seasonal allergic rhinitis that affect about 24 million adults and children in the United States, according to data for 2012 from the Centers for Disease Control and Prevention.

If your immune system reacts to birch pollen, for example, you may be sensitive to related foods such as apples, cherries, carrots and celery.

Oral allergy symptoms develop within a few minutes of eating: The mouth or lips can itch or tingle, and there can be burning or swelling or even tightening of the throat. Usually, oral allergy syndrome causes only a short-term allergic reaction in the mouth and throat, lasting a few minutes or a few hours. Once swallowed, the proteins in the food are broken down by digestive enzymes and acids and do not travel beyond the stomach.

There are few definitive studies, but roughly 30 to 75 percent of people with hay fever may have oral allergy syndrome, according to Anna Nowak-Wegrzyn, who is an allergist-immunologist and an associate professor at the Icahn School of Medicine at Mount Sinai in New York. Many don't even know there is a name for that fleeting itch.

Miriam Keltz Pomeranz, an associate professor of dermatology at the NYU Langone Medical Center, didn't realize she had oral allergy syndrome until she had kids.

Pomeranz had seasonal allergies and related conditions as a little girl. Around age 11, she stopped eating apples because they made her mouth itch. She reacted similarly to peaches, plums, cherries and sometimes hazelnuts and almonds. She simply avoided the foods and never followed up on the minor annoyance.

But the symptoms puzzled her.

Whenever Pomeranz would mention that she couldn't eat fresh apples, everyone had an opinion. They'd tell her to buy organic, avoid pesticides or peel the fruit first.

“It also started to make me feel like maybe I was a little nuts because it became a little Pavlovian,” she said, “like I could smell an apple and it would make my mouth itch sometimes.”

A few decades later, an allergist looking into her child's peanut reaction asked if she had food allergies. Pomeranz said, “No, no, I don't have anything real except for this weird thing that when I eat fresh fruit it makes my mouth itch.”

The allergist told her she had oral allergy syndrome, and Pomeranz was relieved: Finally she had evidence that she had a real condition.

This summer, she asked the dermatology residents she was training if they'd heard of the syndrome. They hadn't, which is not unexpected, since it is usually a topic for allergists, said Pomeranz, who recently co-authored an overview of the syndrome.

Screening for oral allergies

In allergy clinics near Minneapolis, physician Hannelore A. Brucker sees cases of oral allergy syndrome every week. During allergy season she might see it multiple times a day.

She'll screen for oral allergy by asking patients if they itch when they eat apples, for example. Brucker says the allergy is best verified by a test in which a small instrument is used to pierce the raw food and then prick the individual's skin. A food sensitivity reaction might look like a mosquito bite where the skin was tested.

It often takes repeated exposure to pollen to develop this food sensitivity, so it's more common in adults than children. Although Brucker has seen a few patients as young as 5 or 6 with the syndrome, most are adults.

Allergic inclinations persist throughout the year, but oral allergy syndrome can worsen during and right after pollen season, Nowak-Wegrzyn says.

For those with ragweed allergy, which peaks around Labor Day, people with the syndrome may now be experiencing more discomfort than usual from eating ragweed-related foods such as bananas, melons and zucchini.

Those allergic to birch pollen, which hits in the spring, experience the highest rates of oral allergy.

Despite a family history of allergies, I learned about this cross reactivity only when my teenage son with peanut allergies felt his throat swell one day. His symptoms were those expected from a reaction to nuts, but we didn't think he'd been exposed to any.

It took a trip to the emergency room and the allergist for us to learn that his symptoms were caused not by nuts, but because of his allergy to pollen, which caused him to react to some grapes he'd eaten.

Peanuts and tree nuts are among the major food allergens, along with milk, eggs, fish, soy, wheat and shellfish. Because their proteins are not susceptible to digestive processes, they get into the bloodstream and reach tissues where they can produce a life-threatening systemic reaction known as anaphylaxis.

Some people may experience oral allergy syndrome from peanuts and tree nuts, but, given these foods' potential for serious reactions, a doctor should be consulted to determine whether the problem is a minor annoyance or a serious health challenge.

“If you get this reaction to nuts, you should not assume it's oral allergy syndrome,” Pomeranz said.

The oral itching with nut allergies can be the same symptom that you'd get initially from a true food allergy.

“And then you could get really sick the second time you tried it,” she said.

Those who react orally to nuts should see an allergist for blood work that can differentiate between sensitivity to proteins that can cause systemic reactions and those that only cause cross reactivity to pollen.

This is often followed up by a food challenge that entails eating small amounts of the potential allergen under medical supervision, Nowak-Wegrzyn said.

The possibility that oral allergy syndrome will progress into a serious generalized reaction, such as that experienced with major food allergens, is quite small, limited to 2 to 10 percent of patients.

Some individuals may experience varied stomach distress, and for a very few, oral allergy escalates to anaphylaxis.

Eating large amounts of raw food on an empty stomach might make a reaction more severe. Certain foods, including peanuts, tree nuts, peaches and mustard, might increase the risk.

Avoiding the syndrome

The easiest way to avoid oral allergy syndrome is to shun those fruits and vegetables that give you trouble. But oral allergy syndrome can usually be avoided by cooking.

Just as they break down in the stomach, the proteins break down very easily with heat: Raw apples might bring on an itch, but apple pie, applesauce or pasteurized apple juice won't cause problems. Microwaving raw food for 20 seconds sometimes helps, Nowak-Wegrzyn said.

People experience the syndrome in a wide variety of ways, she said. Some report being allergic to the skin of a fruit, but not its pulp. Others say it depends on how ripe the fruit is.

An apple stored somewhere cool for several weeks might be more of a trigger than a very fresh one. People with large tonsils, whose airways may already be somewhat small, may experience more significant symptoms than those with normal tonsils.

Also, taking medications that lower the acidity of the stomach — such as those prescribed for acid reflux — might alter individual response. Sometimes allergy shots can lessen or halt the syndrome, Brucker said.

“For most people, this is harmless,” said Pomeranz, who has lived comfortably with the nuisance. But she cautions that if symptoms are more pervasive than just a little itching in the mouth, “not only should you avoid the food, you should see an allergist and get tested to see if you have signs of systemic allergies.”

When someone with oral allergy syndrome develops reactions to cooked fruits and vegetables, that also signals a need to be evaluated by an allergist, Nowak-Wegrzyn said.

But overall, she said, “For the vast majority of the people who have oral allergy syndrome, this is a mild condition.

Bring on the cherry pie.