Oral allergy syndrome (OAS), also known as pollen-food syndrome, is a type of food allergy that occurs mainly in adults. Its symptoms are mild to moderate and usually affect the mouth, tongue, and throat.

OAS is triggered by the consumption of certain raw fruits, vegetables, and nuts. These foods contain proteins that are structurally similar to the allergens found in pollen. Therefore, people who are allergic to pollen may develop cross-reactivity to these foods.

What are the symptoms of OAS?

The symptoms of OAS usually occur within minutes of eating the offending food. They include:.

Itching or tingling sensation in the mouth, lips, tongue, or throat.
Swelling of the lips, tongue, or throat.
Redness and irritation of the mouth and throat.
Nasal congestion, sneezing, or runny nose.
Itchy or watery eyes.
Upset stomach or nausea.

The symptoms of OAS are usually mild and do not cause anaphylaxis, a severe and life-threatening allergic reaction.

However, in rare cases, OAS may progress into a more severe reaction, especially if the person has a history of severe allergies or asthma. Therefore, it is important to seek medical attention if the symptoms worsen or if you experience difficulty breathing, chest pain, or swelling of the face or limbs.

What are the common triggers of OAS?

The triggers of OAS are foods that contain proteins that are structurally similar to the allergens found in pollen.

Therefore, the most common triggers of OAS are raw fruits, vegetables, and nuts that are related to the pollen that the person is allergic to. For example:.

Birch pollen: triggers OAS to raw apples, pears, peaches, plums, cherries, kiwis, carrots, celery, almonds, hazelnuts, and walnuts.
Ragweed pollen: triggers OAS to raw melons, bananas, cucumbers, zucchinis, and sunflower seeds.
Grass pollen: triggers OAS to raw tomatoes, potatoes, and peppers.
Mugwort pollen: triggers OAS to raw fruits, vegetables, and herbs, such as apples, pears, carrots, celery, parsley, coriander, and fennel.

It is worth mentioning that cooking or heating the offending food may break down the allergenic proteins, thereby reducing the risk of an allergic reaction.

Therefore, people with OAS may be able to tolerate the cooked form of the food that triggers their allergy.

How is OAS diagnosed and treated?

The diagnosis of OAS is based on the patient’s clinical history and symptoms, as well as skin prick tests and blood tests that detect the presence of specific IgE antibodies.

If the diagnosis is confirmed, the patient should avoid the offending food or cook it thoroughly to minimize the risk of an allergic reaction.

In case of a mild reaction, the person can take over-the-counter antihistamines, such as loratadine or cetirizine, to relieve the symptoms.

In more severe cases, the person may need a prescription for epinephrine auto-injectors, such as EpiPen, to use in case of an emergency. It is also essential to carry a medical alert bracelet or necklace that identifies the person as having OAS.

Prevention tips for OAS

The following tips can help prevent or minimize the symptoms of OAS:.

Avoid raw or uncooked fruits, vegetables, and nuts that trigger your allergy.
Cook or bake the offending foods to break down the allergenic proteins.
Eat a variety of fruits, vegetables, and nuts that do not cross-react with your pollen allergy.
Read food labels carefully to avoid hidden sources of allergens.
Avoid eating outdoors during peak pollen season.
Rinse your mouth with water after eating to remove any lingering allergens.
Consult with a registered dietitian or allergist to develop a personalized diet plan.

Conclusion

Oral allergy syndrome is a type of food allergy that affects mainly adults and is triggered by the consumption of certain raw fruits, vegetables, and nuts. Its symptoms are usually mild and affect the mouth, tongue, and throat.

OAS is caused by cross-reactivity between the allergens found in pollen and the proteins found in these foods. Therefore, people who are allergic to pollen may develop OAS. The diagnosis of OAS is based on the patient’s clinical history, symptoms, and tests that detect specific IgE antibodies.

Treatment includes avoiding the offending food or cooking it thoroughly, as well as taking antihistamines or epinephrine in case of a severe reaction. People with OAS should follow prevention tips, such as avoiding raw foods that trigger their allergy and consulting with a registered dietitian or allergist to develop a personalized diet plan.