Hudson Allergy

Oral Allergy Syndrome: Triggers, Symptoms, and How to Avoid It

Does your mouth feel itchy after you eat certain raw fruit and vegetables?

You might have oral allergy syndrome (OAS), an allergic reaction near the mouth in response to proteins in certain raw fruits, vegetables, and tree nuts. The symptoms of OAS include a scratchy throat, itchy mouth, and swelling of the mouth, lips, tongue, and throat. Some people also report itchy ears. Unlike some other types of allergic reactions, the symptoms of OAS do not normally spread beyond the mouth area. Symptoms may subside once the fruit or vegetable is removed from the mouth.

The onset of OAS is less common in young children; it is more common in teens and young adults that have been eating these fruits and vegetables for years without any symptoms or problems.

What are the triggers of OAS?

The allergic reaction occurs because the proteins found in certain fruits, vegetables, and tree nuts are similar to those found in pollen.  As in other types of allergic reactions, in OAS the immune system is “confused” by these proteins and triggers a response in reaction to harmless substances. Patients may be more likely to experience a reaction if the pollen they are allergic to is in the air and they are breathing it in while eating the protein-similar (homologous) fruit, because the immune system has been primed by the pollen exposure to attack similar proteins in the fruit.

It is common for those with birch pollen allergies to experience OAS, but it can also affect those with allergies to alder tree, ragweed, mugwort and grass pollen. Some people may experience allergic symptoms when eating only one food, and others may have an allergic response to a variety of foods.

People with OAS may be able to eat the same fruits or vegetables in their cooked forms because the heating and cooking process distorts the proteins and the immune system no longer recognizes the food. When it comes to celery, nuts, and some berries, however, there may still be the possibility of a reaction even after cooking.

What foods may trigger a reaction for those with birch pollen allergies?

People with birch pollen allergies may experience OAS when they consume raw apples, apricots, cherries, carrots, almonds, hazelnuts, peaches, pears, fennel, green peppers, walnuts, kiwis, plums, prunes, beans, coriander, and nectarines, among others.

What foods may trigger a reaction for those with grass pollen allergies?

If you have grass pollen allergies, you may experience OAS when consuming oranges, peaches, melons, celery, and tomatoes, among others.

What foods may trigger a reaction for those with ragweed pollen allergies?

Cucumbers, melons, bananas, zucchini, and sunflower seeds may trigger OAS if you have ragweed pollen allergies.

How is OAS diagnosed?

An allergist can diagnose OAS after taking a patient’s medical history or after conducting an oral food challenge or a skin prick test. People that experience an OAS reaction that progresses beyond the mouth area may be at an increased risk for anaphylaxis. You should consult with an allergist to determine if you should carry an epinephrine auto-injector.

How can OAS be avoided or treated?

The best way to avoid experiencing OAS symptoms is to avoid trigger foods that may cross-react with your pollen allergies. You may also take oral antihistamine medications to relieve mild OAS symptoms. For some people, allergy shots can ameliorate the symptoms of OAS.

Do you have questions about managing your allergies? Don’t hesitate to reach out to us. We are here to help! Feel free to give us a call at 212-729-1283 or email us at info@hudsonallergy.com.