When Food Makes Your Mouth Itch

It's important to eat fresh fruits and veggies, but what if they make your mouth itch?

Oral allergy syndrome (OAS) is the name for a condition in which a person has an allergic cross-reaction to certain pollens and foods. It’s also known as the pollen-food syndrome. The condition occurs because the body inappropriately recognizes similar proteins in the affected pollens and foods as being “foreign” substances. It is not a true food allergy.

Some of the most common pollens involved in OAS are birch, ragweed, grass, mugwort and alder. People who are allergic to birch may also react to apples, pears, peaches, apricots, cherries, plums, kiwi, nectarines, carrots, celery, raw potatoes, parsnips, peppers, hazelnuts, almonds, walnuts, fennel, parsley and coriander.

Ragweed may be associated with allergy to bananas, melons, kiwi, tomatoes, zucchini, cucumber, dandelion and chamomile tea.

Grass pollens cross-react with peaches, melons, oranges, kiwi, tomatoes and celery.

Mugwort pollen cross-reacts with apples, kiwi, carrots, celery, peppers, peanuts, sunflower seeds, parsley, coriander, caraway seeds, anise and fennel.

Allergy to alder pollen may trigger symptoms from apples, pears, cherries, peaches, celery, almonds, hazelnuts and parsley.

Symptoms of OAS generally occur minutes after eating a trigger food. Common signs include tingling, itching or swelling of the lips, tongue and mouth. Some people also have irritation of the gums, nose and eyes.

The symptoms typically only last a short time, but can still cause a great deal of concern or anxiety for the patient. In rare instances, OAS can cause a severe, life-threatening reaction.

The exact incidence of OAS isn’t known, however, it appears to be more common in adults than in children. Researchers estimate up to 40 percent of adults with allergies to birch, grass and wormwood have OAS. In many cases patients have been eating the trigger foods for years without any problem.

Jane El-Dahr, M.D., Pediatric Allergist at Tulane Medical Center in New Orleans, says sometimes patients won’t develop OAS until after a move and exposure to different kinds of pollens.

 
Traditional allergy treatments don’t help much for food-induced symptoms of OAS because the symptoms are so short-lived. El-Dahr says sometimes pollen allergy shots can help reduce the food symptoms. However, the only sure treatment is to avoid the food triggers. Heat usually destroys the allergy-causing proteins, so people with OAS can often eat the problem foods if they are cooked. Most of the food protein is concentrated in the skin, so peeling may also help reduce risk of symptoms.

It can take some detective work to figure out the connection between pollen and food allergies. El-Dahr says the standard allergy tests don’t typically pick up OAS because the allergy extracts in the test are processed, which destroys the proteins that cause the cross-reactivity. The best way to detect the allergy is to run a pin through the peel and pulp of the food in question, then scratch the skin with the tip of the pin. If the skin reacts, the person most likely has OAS.