Oral Allergy Syndrome: Itchy Mouth and Scratchy Throat

If you have an allergy to pollen and experienced an itchy mouth and/or throat after eating fresh fruit and/or raw vegetables, you may have Oral Allergy Syndrome (OAS). OAS is a cross-reaction that can occur when someone who is allergic to pollen eats certain raw fruit, vegetables or some nuts. Your immune system identifies certain proteins within the food you’re eating as the same as pollen because they look identical. A cross-reaction occurs when the proteins in one substance (typically pollen) are similar to the proteins found in another substance (typically food). And because of this cross-reactivity between pollen and food, OAS is sometimes called Pollen-Food Allergy Syndrome (PFAS).

People affected by OAS can usually tolerate the same fruit or vegetables after they have been cooked because the proteins are distorted during the heating process - the immune system no longer recognizes the food.