Delicious, ripe, mouthwatering fruits and vegetables are more plentiful during these summer months.  However, that that summer breeze may carry more than just excitement for the season. Some people with environmental allergies may notice that certain fruits, vegetables, or nuts give them distinct allergic symptoms, typically confined to the lips, mouth and throat. This phenomenon is known as oral allergy syndrome (OAS).

Oral Allergy Syndrome

Oral allergy syndrome, or pollen food allergy syndrome, occurs when there is a cross reaction or a confusion in the body. Some fruits, vegetables, and nuts have a similar protein to the allergy-causing protein on the surface of the pollen grain. According to the American Academy of Allergy, Asthma, and Immunology (AAAAI), “These proteins can confuse the immune system and cause an allergic reaction or make existing allergy symptoms worse, which is referred to as cross-reactivity.” It is a contact allergic reaction, but it also considered a mild food allergy.

Cross Reactivity

During the summer season, cross reactivity with grass and weed pollen most commonly triggers OAS. Timothy grass, orchard grass, and ragweed pollen tend to cause more reactions. Other grasses and weeds may also contribute to OAS symptoms. People with allergy to timothy grass and orchard grass may experience OAS when consuming foods like peaches, oranges, and tomatoes. Those allergic to ragweed pollen can experience symptoms when eating foods like banana, cucumber, zucchini, and some melons such as honeydew and cantaloupe. Watermelon and white potatoes can trigger a response in both grass and weed pollen sufferers equally.

Symptoms and Treatment

Typically, oral allergy syndrome symptoms present as itching or swelling in the mouth and throat. Symptoms can also be present on the face, lips, or tongue. While the symptoms usually appear immediately after eating raw fruits or vegetables, in rare cases the reaction can occur more than an hour later. Eating the food in the rawest or purest form usually triggers the more severe symptoms. Peeling, cooking, or baking the food can greatly reduce or eliminate a reaction all together.

For most people, the allergy symptoms are localized to their mouth and are uncomfortable or annoying. However, up to 9% of people have reactions that affect a part of their body beyond their mouth. About 1.7% can suffer a life-threatening allergic reaction or anaphylaxis. For this reason, it is crucial for people to determine what might be causing their symptoms with allergy testing and food journals. Avoid eating that allergy-causing food (especially in that foods peak allergy season). It is also beneficial to consider treating the underlying pollen allergy with immunotherapy.

Amanda Hofmann, MPAS, PA-C, is a graduate of Duquesne University, in Pittsburgh, PA. After spending 8 years in clinical practice, she joined United Allergy Services where she is currently the Vice President of Clinical. Amanda is also the past president of the Association of PAs in Allergy, Asthma, and immunology. 

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