As spring arrives, watch out for oral allergy syndrome

Key takeaways:

• Fresh or raw fruits, vegetables and nuts may trigger oral allergy syndrome (OAS).
• OAS often overlaps with tree, grass and weed allergies.
• Allergists can identify these triggers during consultations.

Editor’s Note: In Healio Allergy/Asthma’s column, “Food Allergy: Fact vs. Fiction,” Douglas H. Jones, MD, breaks down what’s true and what’s myth for a variety of topics related to food allergies. If you have a question you would like answered in this column, email Jones at rmaaimd@gmail.com or Richard Gawel at rgawel@healio.com.

Spring is upon us in the Northern Hemisphere, and many patients are experiencing classic “hay fever” symptoms including itch, stuffy nose, sneezing and rash as well as eye symptoms.

Additionally, some patients may be experiencing increased symptoms of itchy mouth and rash with fresh fruits and vegetables. Is this really an allergy?

It is, but it is a bit different than typical food allergies. So, what is happening? It is a condition called oral allergy syndrome (OAS).

Triggers in OAS

Also known as food-pollen syndrome, OAS is a condition in which individuals experience symptoms to certain fresh or raw fruits, vegetables and nuts. These symptoms include itchy mouth or tongue, rash or hives around the mouth, or upset stomachs.

However, if the raw fruit or vegetable is cooked or processed, then the patient will likely not experience any symptoms and can tolerate the food just fine. It typically occurs in people who have allergies to pollen from certain trees, grasses or weeds.

The proteins in the raw forms of these foods are like those found in specific pollens, leading to cross-reactivity and triggering allergic symptoms such as itching, tingling, or swelling in the mouth, throat or lips. Cooking or processing the foods often reduces or eliminates these reactions, as it changes the protein configuration so that it is less similar to those found in the pollens.

While some people can have isolated allergies to these foods, OAS must be assessed. It is important to distinguish between a type 1 food allergy to these foods as opposed to OAS, since the risks and treatment options are different. (We will discuss treatment later.)

Common foods associated with OAS vary, depending on the specific pollen to which an individual is allergic.

Some typical fruit triggers (and this is not an all-inclusive list) include apples, peaches, melons (watermelon, cantaloupe, honeydew), pineapple, kiwi, banana, plums, mango, strawberry and avocado. Vegetable triggers include carrots, celery and tomatoes. Almonds, hazelnuts and walnuts can be triggers as well.

OAS is commonly associated with specific pollens, and the foods that trigger it often correlate with the pollens to which an individual is allergic. Common pollen triggers for OAS include birch, ragweed and grass.

Foods associated with birch pollen include apples, pears, cherries, peaches, plums, carrots, celery, almonds, hazelnuts and walnuts.

Foods associated with ragweed pollen include melons (cantaloupe, honeydew), bananas, cucumbers, zucchini and sunflower seeds.

Foods associated with grass pollen include tomatoes, potatoes, oranges and peaches. Corn and wheat (while not a fresh fruit or vegetable) also commonly cross-react with grass pollens.

It is important for individuals experiencing symptoms of OAS to identify their specific pollen allergies and associated food triggers. Consulting with an allergist can help in diagnosing and managing the condition effectively.

Treatment for OAS typically focuses on managing symptoms and avoiding triggers. Multiple approaches are available.

Avoidance

Identify and avoid foods that trigger allergic reactions. Cooking or processing the foods may help reduce or eliminate symptoms since heat can break down the proteins responsible for the reaction.

Oral antihistamines

Over-the-counter antihistamines such as loratadine (Claritin, Bayer), cetirizine (Zyrtec, Johnson & Johnson) or fexofenadine (Allegra, Sanofi) can help relieve mild symptoms such as itching or swelling in the mouth or throat. Please, no diphenhydramine (Benadryl, Pfizer)!

Epinephrine

For severe reactions or anaphylaxis, individuals may need to carry an epinephrine autoinjector such as an EpiPen (Mylan/Viatris) and be trained to use it in case of emergency. While there is less risk for anaphylaxis with OAS, it is not zero or completely negative. It is better to be prepared and have the emergency medication in place.

Allergy shots or environmental allergen immunotherapy

In some cases, allergists may recommend allergen immunotherapy (AIT) to desensitize the body to specific environmental allergens, potentially reducing the severity of OAS symptoms over time. Having said that, many people will seek an allergist to see if food oral immunotherapy is a treatment option for their allergies to fruits and vegetables.

As mentioned previously, OAS must be distinguished from a type 1 food allergy to these fruits and vegetables. AIT or allergy shots are appropriate for those with OAS, but OIT would be the treatment of choice for type 1 food allergy to these fruits and vegetables. Make sure an allergist is involved to help distinguish between these important differences.

This leads me to my last point.

Consultation with an allergist

An allergist can provide a proper diagnosis, identify specific allergens, and develop a personalized treatment plan tailored to individual needs.

It is essential for individuals with OAS to work closely with health care professionals to manage their condition effectively and minimize the risk of severe allergic reactions.

For more information:

Douglas H. Jones, MD, FAAAAI, FACAAI, is cofounder of Global Food Therapy, Food Allergy Support Team and OITConnect, the director at Rocky Mountain Allergy at Tanner Clinic, and a Healio Allergy/Asthma Peer Perspective Board Member. He can be reached at rmaaimd@gmail.com or on Instagram @drdouglasjones.