Oral allergy syndrome is an allergic reaction that specifically affects the tongue, mouth, lips, and throat. It is related to allergic rhinitis, or hay fever. However, oral allergy syndrome is not seasonal.

In oral allergy syndrome, the body cross-reacts to certain proteins in specific foods. These proteins are similar to the proteins found in the pollens that are associated with hay fever and seasonal allergies.

As these foods are typically available throughout the year, the condition is not seasonal.

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For many, the key signs of oral allergy syndrome are swelling and itchiness of the:

  • lips
  • mouth
  • tongue
  • throat

This most commonly occurs immediately after eating certain fruits and vegetables, especially when raw.

Symptoms typically do not occur beyond the mouth and throat and resolve quickly once you finish eating or remove the offending item. However, in rare cases, this allergic reaction can lead to anaphylaxis, which is a medical emergency.

Additional symptoms can include hives and asthma. Typically, hives occur when the food is peeled, chopped, or grated. Asthma occurs when the food is blended or vaporized, such as during stir-frying.

Those who experience more severe symptoms should see their doctor.

To protect the body, your immune system identifies harmful bacteria, viruses, and other unwanted germs and launches defense responses.

However, it sometimes identifies typically-harmless substances, such as pollens, as threats. The body reacts to these allergens with a significant immune response, which leads to swelling, various other allergy symptoms, and discomfort.

Typically, oral allergy syndrome results from plant or tree pollens cross-reacting with specific foods to cause tingling and itchiness upon eating. This is often referred to as cross reactivity. Trees, grasses, and weeds that commonly cause allergic reactions include the following:

  • Trees
    • birch
    • alder
    • Japanese cedar
    • plane
  • Grasses
    • Timothy
    • orchard grass
  • Weeds
    • wormwood
    • ragweed
    • mugwort
    • Parietaria species


As there is a wide range of potential causes of allergic rhinitis, there is also an extremely varied range of fruits and vegetables that cause oral allergy syndrome.

Similarly, different fruits and vegetables may cause a different response depending on the type of pollen the immune system cross-reacts to.

Fruits that may cause oral allergy syndrome include:


Vegetables that may cause oral allergy syndrome include:

Other causes

Other food-based causes of oral allergy syndrome include:

Diagnosing oral allergy syndrome often involves several steps. These often include:

  • medical history assessment
  • symptom checking in the presence of known allergens
  • skin prick testing with pollen, fruit, or vegetable extract
  • blood test

If a person is unsure what is causing their reactions, doctors may recommend an elimination diet to determine the offending allergen.

There are no standard treatments for oral allergy syndrome other than avoiding specific foods that are associated with allergy symptoms.

However, in the event of an allergic reaction, initial treatment generally involves rinsing the mouth with water and then resting. Taking antihistamines can also prevent effects from lingering and should be taken as soon as the reaction occurs.

Diet tips

In many cases, avoiding food completely is the only sure way to prevent the symptoms of oral allergy syndrome. However, there are some methods that people may wish to try so they can enjoy their favorite foods.

  • Planning: Diet and meal planning can help people reduce their exposure to irritants and allergens.
  • Cooking: In some cases, cooking foods can destroy the proteins that cause oral allergy syndrome. However, this depends on the foods that trigger the allergies.
  • Preparation: There is usually a large amount of these proteins in the skin, so peeling fruits before consuming them may reduce reactions significantly.

People with oral allergy syndrome often find that their symptoms worsen during pollen season, so they may wish to avoid trigger foods at the peak of that season.

Oral allergy syndrome is an allergic reaction to foodstuffs that can cause swelling and itching in the mouth, lips, and throat.

The most common causes of oral allergy syndrome are raw fruit and vegetables. These items may contain proteins that the body has a reaction to, but may also host reaction-inducing pollens on their skins.

Symptoms typically resolve once the offending item is removed from the mouth and lips. However, in rare cases, a person may react severely to these allergens and experience greater discomfort or even anaphylaxis.