Oral Allergy Syndrome

There are many individuals with seasonal hayfever symptoms (itchy eye and nose, sneezing and nasal congestion) who may also experience allergic symptoms in and around the mouth after eating certain foods.  These include raw vegetables, nuts, seeds, or fresh fruits. This type of reaction is know as Oral Allergy Syndrome.

 

This type of localized allergic reaction in and around the mouth is called the oral allergy syndrome.  The link between pollen allergy and these allergic food reactions is shared allergenic proteins that are present in both pollen and fresh food.  

 

The foods most commonly associated with oral allergy syndrome are the following:  vegetables – carrots, celery, parsley, potato; seeds and nuts – fennel seed, hazelnut (Filbert) and sunflower seeds; fruits – apple, apricot, banana, cantaloupe, cherries, honeydew, orange, peach, pear, tomato and watermelon.

 

The symptoms of oral allergy syndrome may include itching or swelling of the lips, tongue, throat, or roof of the mouth.  It is uncommon for individuals who have this syndrome to have stronger allergic reactions that involve swelling in the airway or generalized hiving that may produce more serious life-threatening reactions.

 

It has been observed that individuals who are sensitive to these raw vegetables, nuts, or fresh fruits may, however, eat these products if they have been cooked, baked, or canned.  This is due to the destruction of the alleged allergen proteins by heating or digestion.  For example, an individual may experience itching of the mouth and tongue after eating a fresh peach, but he/she may be able to eat peaches skinned or baked, as in a peach pie, without trouble.
            

As mentioned above, it is important to distinguish between oral allergy syndrome and food induced anaphylaxis.  Although both types of reactions are caused by specific allergy antibodies, anaphylaxis is a much more severe form of food allergy and may be associated with hives, swelling of the lips, eyelids, face, or hands, trouble breathing and/or loss of consciousness.  Most food induced anaphylactic reactions are due to a different set of common foods including peanuts, tree nuts, fish, milk, eggs, or shellfish.  However several foods, particularly celery, seeds, or nuts, can cause either anaphylaxis or the oral allergy syndrome.  Often, however, the symptoms of oral allergy syndrome are limited to the mouth, lips and throat and usually go away without treatment.
            

The proper treatment of oral allergy syndrome may be identical to that for anaphylaxis in that avoidance is recommended.  However, if there is any doubt as to whether an individual’s symptoms are due to oral allergy syndrome or anaphylaxis, it is safe to administer oral antihistamines and perhaps even adrenaline.
 

The diagnosis of oral allergy syndrome can be made based on the individual’s history and skin test reactivity to pollens and to foods.  Often individuals are skin test positive to pollens, but when tested with commercial extracts of fruits and vegetables and/or blood tested for food specific allergy antibodies, they may produce negative results in many cases.  However, when skin tested with fresh fruit or raw vegetables, they are often positive. 

 

Not much is known about whether oral allergy syndrome disappears or waxes and wanes.  Some researchers report that both hayfever symptoms and oral allergy syndrome symptoms go away if the affected individual receives allergy injections to pollen.  As with all forms of food allergy, identification of the responsible food and strict avoidance is essential for long term management.

 

Mouth or throat itching from peanut, soybean, almonds and hazelnuts may also be an initial manifestation of a more serious food allergy with the potential for anaphylaxis. See an allergist / immunologist if such symptoms are noted.