Oral Allergy Syndrome: Why does my mouth itch when I eat certain fruits, nuts and vegetables?

Summer is the season when New Yorkers tend to eat more fruits. Certain fruits, vegetables and nuts can cause oral itching and other symptoms in people with various pollen allergies, particularly tree pollen. The symptoms, which may also include nasal, eye and even gastrointestinal symptoms, usually occur within minutes of eating the food. Rarely, the food exposure can result in anaphylaxis, a more generalized life-threatening reaction marked by low blood pressure, hives and wheezing.

What is this condition called?

The syndrome is called oral allergy syndrome or pollen-food allergy.

What causes it?

This condition is a result of cross-reactivity of proteins in the pollen and food. The proteins in some fruits and vegetables are similar to proteins in some pollens, so when a person with pollen allergy eats a particular fresh fruit or vegetable, for example, his or her immune system sees the similarity in the plant proteins and triggers an allergic reaction.

What are the most common pollen-food cross-reactions?

Birch tree pollen is the most common culprit among tree pollens for causing this cross-reactivity. Apples are the most common food culprits in birch pollen cross-reactivity, followed by peaches, cherries, plums and almonds, but numerous other foods have been implicated, too. Some patients only experience this during the pollen season in question (April or May for birch), while others have these symptoms year round.

Other pollen sensitivities cross-react with other fruits and vegetables, as well. For example, grass pollen cross-reacts with figs, melons and tomatoes. And, ragweed frequently cross-reacts with melons and many other fruits. Some patients with latex (rubber) allergy have similar reactions with foods, particularly tropical fruits.

How is it treated?

Avoidance of the raw fruit or vegetable is the recommended treatment. Most patients will tolerate the fruit without the skin or if it’s cooked. Since exposure to the known foods or a new food can result in anaphylaxis (rarely), we often err on the safe side and prescribe patients auto injectors of epinephrine (such as EpiPen) to use for such severe reactions.

Should I see a doctor?

Enjoy the rest of summer and a healthful assortment of fruits and vegetables. But, if you experience symptoms described above, you should check with your doctor.

To find an excellent doctor who is right for you, please call our Physician Referral Service at 866.804.1007.

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