Do Some Fruits Make Your Mouth Itch and Burn?

Regular readers now know that when a person has allergies, the basic underlying problem is that the immune system incorrectly identifies normal parts of the environment as potentially harmful and it sets up a reaction to try and get rid of them.  What the immune system is really recognizing is proteins found in these substances.  We call these proteins antigens.  So, in a whole pollen grain, there may be several small protein antigens that the body is sensitive to.

So, what does this have to do with fruits and oral itching and burning?  Well, many fruits contain proteins that are structurally similar to protein antigens found in pollens, particularly birch tree pollen, but also other trees and ragweed.  The list of fruits is long, but includes apple, pear, cantaloupe, banana and kiwi.  So when a pollen allergic person eats a fruit with a structurally similar protein, they may experience intense itching and burning of the lips, mouth and throat.  Occasionally, there is mild swelling as well.

This phenomenon is called Oral Allergy Syndrome. (Some academic allergists are trying to change the name to Pollen/Food Syndrome). The good thing about OAS is that reactions are usually just local and are more irritating than dangerous. A few studies suggest that treatment with immunotherapy can lessen or stop OAS reactions and my own experience backs this up.

It is important to differentiate between annoying OAS and potentially dangerous food allergy. Simple allergy tests can answer this question.

Dr. O