Why Does My Tongue Itch: Oral Allergy Syndrome

Introduction

Have you ever eaten a piece of fruit or a vegetable and felt a tingling or itchy sensation in your tongue or throat afterward, even if you have no history of allergies? After some time passed, you may have taken an allergy medication or maybe the sensation went away on its own. What you may have experienced is an oral allergy syndrome allergic reaction and it can happen to anyone, with and without known severe allergies.

Oral Allergy Syndrome

Oral allergy syndrome (OAS) is a condition which results in allergic reactions limited to the mouth and throat, often presenting as a swelling, tingling, and/or itching sensation. It is commonly seen among people who suffer from seasonal pollen allergies and may also be referred to and Pollen Food Allergy Syndrome (PFAS).

Oral allergy syndrome occurs when proteins found in fruits or vegetable are similar to those of various pollens. When we consume these proteins by eating the fruits or vegetables, the immune system mistakenly recognizes it as pollen and stimulates an allergic reaction, typically manifested as an itchy or swelling tongue and lips, sore or scratchy throat, and/or hives on the mouth. Each person with OAS may react differently, and some experience it only when seasonal allergies are at their highest. Others may react every time they eat a particular type of produce, year round. Because the condition varies from person to person, it is important that when an OAS allergic reaction occurs, an allergist is consulted to discuss how to treat the condition moving forward.

Cross-Reactivity of Pollen

As mentioned previously, oral allergies are an immune response to certain types of produce that share similar proteins to those of different weed, tree, and grass pollens. This is known as cross-reactivity and while reactions may vary from person to person, certain pollens are associated with specific types of fruit, vegetable, spice, or nut. For example, those with seasonal allergies to birch trees may have an oral allergy to peanuts, apples, or celery. Below is a chart of several common oral allergies and what pollens they are associated with.

Diagnosis

Oral allergy syndrome can be diagnosed through a combination of testing and clinical history analysis. Allergists may test patients using either a skin prick test (when a controlled amount of the allergen is poked into the skin), blood tests (which evaluate Immunoglobin E antibody levels in the blood that, if elevated, can indicate a positive allergic response), or an "oral food challenge" (where the patient is heavily monitored as they consume increasing doses of the suspected allergen).

When physicians and allergists look at clinical history to assess whether an oral allergy may be present or not, they take into account related conditions such as allergic rhinitis, asthma, or food allergies.

Prognosis

Typically oral allergy syndrome is not severe and remains localized to the mouth and throat, however, if you experience an oral allergy reaction, you should visit an allergist for testing in order to ensure the allergy is not going to escalate to anaphylaxis. In very rare cases (~2% of cases), an oral allergy may be anaphylactic and require prescribed epinephrine injections. In many cases, the allergic reaction occurs only when consuming the food item raw. This is because when heat is applied during cooking, the protein structure of the food is altered and becomes less allergenic.

Prevention

The simplest and most effective preventative measure for oral allergy reactions is avoiding the raw foods that cause a reaction. It is important to consult an allergist to verify that you can continue to eat the cooked food.

Sources

Allergy & Asthma Network. “Oral Allergy Syndrome (OAS) | Allergy & Asthma Network.” Allergyasthmanetwork.org, allergyasthmanetwork.org/health-a-z/oral-allergy-syndrome/.

American Academy of Allergy, Asthma & Immunology. “Oral Allergy Syndrome Symptoms, Diagnosis & Treatment | AAAAI.” Aaaai.org, 2021, www.aaaai.org/Tools-for-the-Public/Conditions-Library/Allergies/Oral-allergy-syndrome-(OAS).

Food Allergy Canada. “Oral Allergy Syndrome (OAS)/Pollen Food Allergy Syndrome (PFAS).” Food Allergy Canada, foodallergycanada.ca/food-allergy-basics/related-conditions/oral-allergy-syndrome-oas-pollen-food-allergy-syndrome-pfas/.

Uptown Allergy & Asthma. “Oral Allergy Syndrome Chart & Treatment in New Orleans.” Uptown Allergy & Asthma, 5 May 2025, uptownallergyasthma.com/oral-allergy-syndrome/. Accessed 24 Aug. 2025.

Assessed and Endorsed by the MedReport Medical Review Board