Oral Allergy Syndrome

apple tree branchOral allergy syndrome can be seen in patients with pollen allergy who experience mouth and throat itching, typically with fresh fruit and vegetables such as apples, melons, celery and carrots, but also with peanuts and tree nuts such as hazelnut. Most symptoms are felt in the mouth, but there may also be gastrointestinal symptoms such as nausea, vomiting, diarrhea and abdominal pain. Occasionally patients also describe symptoms similar to pollen exposure such as itching eyes and nose, congestion and runny nose. Rarely patients develop throat swelling, hives or anaphylaxis.

Most often oral allergy syndrome begins with a pollen allergy such as birch, ragweed or grass. Oral symptoms are seen among 70% of birch sensitive patients and 20% of grass sensitive patients. An allergy to particular foods may follow.

Compounds in certain foods are similar to compounds on the surface of pollen grains. Acting as a local allergen, these compounds can trigger itching in the mouth and throat among sensitized individuals. Many of these compounds are concentrated near the skin of fruits, so a peeled apple may cause fewer symptoms than the unpeeled fruit. Many food allergens degrade with cooking and digestion; apple sauce may cause fewer symptoms than fresh apples, carrots in a soup may cause fewer symptoms than raw carrots. Those on stomach acid blocking medications may experience more gastrointestinal symptoms, as these medications impair gastric digestion.

Pollen           Related foods which may cause symptoms
Birch             Apple, carrot, celery, cherry, peach, apricot, pear, potato,
                    hazelnut, peanut
Ragweed       Cantaloupe and other melons, banana, zucchini, mango
Grass            Carrot, celery, wheat
Cedar            Apple, cherry, bell peppers, kiwi, paprika, tomato
Mugwort        Broccoli, cantaloupe, carrot, celery, mustard, peanut,
                    sage, rosemary

Oral allergy symptoms are seen more often during peak allergy season: spring for birch, summer for grass and fall for ragweed. Symptoms may become more noticeable if large or frequent amounts of a food are eaten. An apple a day may be OK, but that bushel may not keep allergies away.

The mainstays of treatment are:

  • Strict avoidance may not be necessary, but limit the amount and frequency of foods which cause symptoms, particularly during peak allergy seasons.
  • Treatment of the underlying pollen and food allergy with sublingual immunotherapy.
  • Oral antihistamines as needed for symptom control.

Webber CM, England RE. Oral allergy syndrome: a clinical, diagnostic, and therapeutic challenge. Ann Allergy Asthma Immunol. 2010;104:101-108