Understanding Oral Allergy Syndrome

Food allergies can be confusing, especially when you’re trying to figure out what your child is allergic to. Oral allergy syndrome can often make this a little trickier. Here’s what you need to know about oral allergy syndrome and food allergies.

Oral Allergy Syndrome

Oral allergy syndrome (OAS) is a reaction to the proteins in foods that are very similar to those found in pollen. In OAS, a person has an allergy to pollen, not to the foods they are reacting to. 

Food allergies are a direct reaction to a food protein. 

OAS symptoms are limited to itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue. Symptoms quickly resolve once the food is swallowed or removed from the mouth, and are not life threatening. 

Symptoms of food allergy are more severe and affect multiple body systems. However, in very rare cases, oral allergy syndrome can cause more severe symptoms.


Swelling, tingling, and itchiness of the lips and tongue are the signs of oral allergy syndrome. 

Because OAS happens in people with seasonal allergies, symptoms are often worse during pollen season. Common pollen allergies overlap with oral allergy syndrome to specific foods as seen in the table below. 

Alder Pollen

Birch Pollen

Grass Pollen

Mugwort Pollen

Ragweed Pollen

  • Almonds
  • Apples
  • Celery
  • Cherries
  • Hazelnuts
  • Parsley
  • Peaches
  • Alder Pollen list
  • Aniseed
  • Apricots
  • Carrots
  • Carraway
  • Coriander
  • Fennel
  • Kiwi
  • Nectarines
  • Parsnips
  • Peanuts
  • Peppers
  • Plums
  • Potatoes
  • Soybeans
  • Melons
  • Tomatoes
  • Oranges
  • Peanuts
  • Swiss Chard
  • Raw Potatoes
  • Bell Pepper
  • Broccoli
  • Cabbage
  • Carrots
  • Cauliflower
  • Celery
  • Caraway
  • Coriander
  • Fennel
  • Garlic
  • Onion
  • Parsley
  • Peach
  • Peppers
  • Sunflower
  • Banana
  • Cantaloupe
  • Cucumber
  • Honey Dew
  • Kiwi
  • Sunflower
  • Watermelon

Oral allergy syndrome typically does not happen in babies, and is more common in teens and adults, which is also when you start to see more cases of seasonal allergies or hay fever. While there is no definitive test for OAS, a positive allergy skin test or blood test for a pollen, along with a history of symptoms, can be used to make this diagnosis.

In general, oral allergy syndrome is not a cause for concern, though in some cases it can worsen over time and progress to a food allergy. 

Treating Oral Allergy Syndrome

The most common treatment for oral allergy syndrome is to simply avoid any foods that cause discomfort. Some people with oral allergy syndrome can eat the foods they react to  if it is: 

  • Washed well
  • Peeled or skinned
  • Cooked / boiled / baked

For some people, treatments for pollen allergies including allergy shots and sublingual immunotherapy (SLIT) can reduce their reactivity to pollens and resolve the oral allergy syndrome as well. 

An allergist can help evaluate for oral allergy syndrome as well as come up with a plan to manage and treat the condition.