Oral Allergy Syndrome

Oral Allergy Syndrome or OAS is also called pollen-food allergy syndrome. This syndrome is due to a “food allergy” caused by uncooked fruits, raw vegetables, spices and nuts. It is not an actual food allergy, but instead a reaction to certain foods that can develop in people with allergies to pollen. The immune system mistakes the food proteins for the pollen proteins and causes symptoms. See the
chart for a list of foods that cause problems for people with pollen allergies.

The reaction to these foods can occur anytime of the year when eating the foods, but can be worse during the pollen season when your child is having allergic rhinitis/hay fever symptoms. These symptoms begin quickly after the food is put in the mouth and usually lasts only a few minutes after the food is swallowed. OAS is common for people with spring allergy symptoms from birch pollen, or late summer hay fever from ragweed pollen. 

What are the symptoms of OAS?

An allergic reaction happens while eating the raw food. These reactions occur in the mouth and throat. Symptoms may also happen when peeling fruits or vegetables, or if the juice touches the lips.

• Most common symptoms of a reaction are:
• Itchy, tingly mouth, lips, or throat
• Very mild swelling of the lips, tongue, or throat
• Watery, itchy eyes, runny nose, sneezing

Some people develop itching, redness, or slight swelling of the hands if they peel or handle the raw fruits or vegetables that cause OAS, such as mangoes, apples, or white potatoes.

OAS symptoms can be very specific to a variety of fruit. Granny Smith apples tend to cause more OAS symptoms than Fuji apples.

About 10 percent of people with OAS may experience nausea or stomach pain. An even smaller number of people, fewer than 5 percent, develop more serious whole body allergic reactions, such as
throat tightness, chest tightness, difficulty breathing, wheezing, vomiting, diarrhea, or loss of consciousness. If your child should begin to experience more severe symptoms, do not eat that food
again until speaking with a healthcare provider. This may represent a more significant food allergy and you may need an auto-injectable epinephrine shot.

Severe allergic reactions to food causing OAS are most likely to occur with celery, kiwi, peaches, apricots, apples, and nuts, especially hazelnuts. 

Tips for Management of Oral Allergy Syndrome:

1. These reactions are usually caused by the raw fruit or vegetable. Your child may be able to eat the food if it is cooked, canned, micro-waved or baked. For example, someone allergic to raw apples can eat applesauce, apple jelly, apple juice, apple pie and dried apples. Try microwaving fruits and vegetables.
2. For mild Oral Allergy Syndrome try peeling the fruit because the more allergic part of the fruit might be in the skin. The allergic reaction is not due to pesticides, chemicals or wax on the fruit. It is also better to give your child unripe or partially ripe fruits, or pick it directly from the tree so it is fresh. Freshly picked fruit and unripe fruit may cause fewer symptoms than fruit that has been stored for several weeks or very ripe fruit.
3. Antihistamines and allergy shots for allergic rhinitis/hay fever may sometimes help prevent or reduce symptoms associated with Oral Allergy Syndrome.

Foods that may cause a reaction in people with pollen allergies