Oral allergy syndrome (OAS) is common among people with pollen allergy. It is normally a temporary and relatively mild condition characterized by swelling, redness and itching of the mouth area. Occasionally, also the eyes are affected.
Oral Allergy Syndrome (OAS) can occur in pollen allergic individuals, when eating certain fruits, vegetables, nuts or beans. The symptom appears due to the fact that pollens contain proteins of similar structure to those present in this particular food. This is called a cross-reaction.
OAS is thus not a separate food allergy, but rather represents cross-reactivity between pollen and certain fruits and vegetables. It is usually limited to ingestion of only uncooked fruits and vegetables.