Pollen-food allergy syndrome (also called oral allergy syndrome) causes a type of allergic reaction. It usually only affects the lips, mouth, and throat, and happens when someone with a pollen allergy eats certain foods — most commonly raw fruits, vegetables, and nuts.
What Happens in Pollen-Food Allergy Syndrome?
In pollen-food allergy syndrome (PFAS), a person’s immune system thinks proteins in some foods are like pollen proteins. This is called a “cross-reaction.” When these foods touch the person’s mouth and throat, they will start to feel symptoms within minutes.
What Are the Signs & Symptoms of Pollen-Food Allergy Syndrome?
After they eat foods like raw fruits and vegetables, people with PFAS can get symptoms such as:
itching or tingling of the mouth and throat (the most common symptom)
feeling of throat discomfort
lip/face swelling or redness
itching of the ears and nose
Symptoms usually happen right away and last for a few minutes to half an hour. Rarely, symptoms of a severe allergic reaction can happen.
Some people can eat foods without having symptoms if the skins are peeled. And many people won’t have symptoms if they eat cooked fruits or vegetables because the food proteins that cause these symptoms change with heating. For example, a person who has mouth itching when eating a raw apple might be able to eat apple pie without a problem. Someone who reacts to peanuts or tree nuts may still get symptoms, though, because the proteins in these do not change as much with cooking.
Which Foods Can Cause Symptoms?
The types of pollen someone is allergic to (such as tree pollen, grass pollen, or weed pollen) determine which foods will cause symptoms.
These pollen proteins and food proteins can cross-react:
Not all people who have pollen allergies have PFAS symptoms with foods. And someone may have symptoms with some foods in a group and be OK with other foods in the same group.
How Is Pollen-Food Allergy Syndrome Diagnosed?
Doctors diagnose pollen-food allergy syndrome based on a person’s symptoms and a skin prick test. The test is done in an allergist’s office. The test helps the allergist see what pollens or foods a person is allergic to. Sometimes they also order blood tests.
People who have had symptoms from peanuts or tree nuts can be at risk for more severe reactions. They should see an allergist to find out if they need to carry an epinephrine autoinjector in case of a reaction.
How Is Pollen-Food Allergy Syndrome Treated?
Treating PFAS involves avoiding foods that cause symptoms. The doctor can let you know if peeling or heating the foods will help.
Symptoms usually go away quickly and don’t need any medicine. But sometimes doctors:
Prescribe an epinephrine autoinjector to use in case of a reaction for someone who had an allergic reaction involving more than just the mouth or throat, or who had severe symptoms.
Recommend allergy shots (allergen immunotherapy) for people who have serious seasonal symptoms related to pollen allergies.