Oral Allergy Syndrome (OAS) is the cause of cross-reactivity, where proteins can confuse the immune system and cause an allergic reaction. This confusion can be caused when, for example, your mouth becomes itchy after eating an apple or celery. This happens because the proteins found in some fruits and vegetables are very similar to those found in pollen, which is a common allergy.

This Syndrome is also pollen fruit syndrome (PFS). Contact of the mouth and throat with raw fruits and vegetables is a form of a contact allergic reaction for OAS. There are several other possible forms of contact allergic reaction for OAS, but contact of the mouth and throat with raw fruits and vegetables is the most common.

Symptoms of Oral Allergy Syndrome

Even though Oral Allergy Syndrome is generally considered to be a mild form of food allergy, it can cause severe throat swelling leading to difficulty swallowing or breathing. This is rare for most cases of OAS, though. Anaphylaxis, a possible life-threatening condition, can also be caused by a pollen cross-reactive raw fruit or vegetable, but this is only seen with people that are highly allergic and is generally uncommon. The occurrence of OAS is possible at any time of the year.

Someone might experience:

• Itchiness of the mouth
• Swelling of the mouth, face, lips, and tongue.

When should I talk to my Physician?

You should talk to your physician if:

• You’re experiencing substantial throat discomfort.
• Symptoms of OAS are increasingly worsening.
• Cooked fruits, vegetables or nuts are the cause of your OAS symptoms.
• Hives, vomiting or difficulty breathing become systematic reactions after eating raw fruits or vegetables.