Recognizing oral allergy syndrome

If you are someone who suffers from hay fever also called seasonal allergic rhinitis, you may also have experienced itchiness in your mouth, tongue or throat when eating certain foods such as watermelon, peaches or apples.  You may have determined that you are allergic to these foods when in reality, what you most likely have is oral allergy syndrome (OAS) also known as pollen-food syndrome.  OAS is considered to be a mild form of a food allergy.  The symptoms develop quickly after eating certain foods and rarely do they progress to a more serious reaction of severe throat swelling, difficulty breathing or a systemic reaction called anaphylaxis.

OAS usually does not appear in children as the onset is more typical in teens or adults.  People who develop this usually have problems with hay fever, or have an allergy to birch, ragweed, grass pollens or latex.  Up to a third of pollen allergy sufferers can develop OAS and around 50 to 75% of adults allergic to birch tree pollen have it. 

Why OAS develops

The proteins found in certain fruits and vegetables are very similar to those found in pollen.  Sometimes these proteins found in certain produce, will be perceived by the immune system as dangerous particles.   Basically it’s confusing the immune system, which is only doing its job of trying to protect you, by causing an allergic reaction which is known as cross-reactivity resulting in OAS.  OAS is a form of a contact allergic reaction since the reaction occurs when a person eats raw fruits and vegetables that contain these proteins and they come into contact with the mouth and throat.      

Symptoms of OAS

·Itchy mouth, tongue, throat and sometimes even ears

·Swelling of the lips, mouth, tongue and throat


·Runny nose

·Watery or itchy eyes

When symptoms occur, it’s due to the immune system trying to flush these foreign particles from the body.  Generally the symptoms are confined to one area and usually do not progress beyond the mouth.  Once the food has been swallowed or removed from the mouth, the symptoms go away quickly and treatment is usually not needed. 

Foods with proteins that may cross-react with certain pollens

Birch Pollen Allergy – Apples, almonds, carrots, celery, cherries, kiwi, pears, peaches, plums, coriander, fennel, and parsley

Ragweed Pollen Allergy – Bananas, cucumbers, melons such as cantaloupe, honeydew and watermelon, tomatoes, chamomile tea, sunflower seeds and zucchini

Grass Pollen Allergy – Celery, melons, oranges, peaches, and tomatoes

Natural Rubber Latex Allergy – People can react to latex and may notice a reaction to these foods: bananas, avocadoes, kiwi, chestnuts, and papaya

Getting diagnosed for OAS

Never assume that when you have a reaction to a food with mild symptoms that it is automatically OAS.  Seek the advice of a board certified allergist to determine what exactly you are allergic to, is it safe for you to eat the food and whether you are a candidate for allergy shots.     In order to rule out whether it’s OAS, a food allergy, or food intolerance, a skin prick test is advisable.  A light scratch on your back or forearm will be performed that contains the protein trigger.  It’s considered to be an allergic reaction if the spot reacts by swelling or turning red in about 15 minutes. 

Treatment for OAS

Once it’s been determined to be OAS, the main thing you can do is to avoid the food that brings on symptoms.  However, most people with OAS can tolerate eating the food when it is well-cooked.  For example, you may have symptoms eating a raw apple but not applesauce, which has been cooked.  Heat breaks the proteins that trigger the reactions causing the immune system to not overreact.  Sometimes peeling raw produce can help avoid a reaction or foods that have been canned may also be tolerated. 

When symptoms arise that appear to be OAS, speak with your physician about getting a proper diagnosis and whether you need to carry an epinephrine pen to treat more severe reactions and know make a list of foods you need to avoid.