Some people who are allergic to pollen develop itchiness or swelling of the mouth, face and throat when they eat certain fruits and vegetables. This is known as oral allergy syndrome. Symptoms usually occur within minutes of eating the food.
Oral allergy syndrome is caused by a cross-reaction between various pollens and certain proteins in fruits, vegetables and nuts that are structurally similar to the proteins in pollen. The immune system becomes confused and causes an allergic reaction that can lead to an itchy, tingly mouth and sometimes a mild sensation of swelling in the mouth or lips. Occasionally, blisters may result.
Symptoms sometimes worsen during pollen season because of a boost in pollen-allergic antibodies. Not all pollen-allergic patients have symptoms, and some will react to one or two foods, while others may react to multiple foods. Adults tend to be affected more often than children.
Non-plant-based foods, such as milk, egg and seafood, do not cause oral allergy syndrome. The following are foods that cross-react with pollens.
Foods that cross-react with birch tree pollen:
- Fruits (apple, peach, apricot, cherry, plum, pear)
- Nuts (almond, hazelnut)
- Vegetables (carrot, celery)
- Spices (parsley, caraway, fennel, coriander, aniseed)
Foods that cross-react with ragweed pollen:
- Fruits (watermelon, honeydew melon, cantaloupe, banana)
- Vegetables (zucchini, cucumber)
Foods that cross-react with mugwort pollen:
- Vegetables and spices (carrot, celery, bell pepper, onion, cauliflower, cabbage, broccoli)
- Spices (parsley, caraway, fennel, coriander, aniseed, black pepper, garlic, mustard)
Foods that cross-react with grass pollen:
- Fruits (melons, orange)
- Vegetables (potato, tomato, Swiss chard)
- Legumes (peanut)
Your doctor can diagnose oral allergy syndrome by reviewing your clinical history and, in some cases, conducting skin prick tests and oral food challenges with raw fruit or vegetables.
What to do if you have oral allergy syndrome:
- Discuss your symptoms with your doctor, and develop a plan. You may be able to continue eating the foods, but you should first discuss it with your doctor.
- Peeling the fruit may reduce symptoms since the allergenic protein is often concentrated in the skin.
- Cooking or baking the food will significantly reduce symptoms. For example, if you have symptoms after eating raw apples, you should be able to eat apple pie or drink apple juice without a problem. This is because heating the food changes the allergens that cause the symptoms.
- (An important exception is tree nuts and peanuts, which still typically cause symptoms even when roasted, in patients with true food allergies to them.)
- Some people with oral allergy syndrome are prescribed an EpiPen, but it’s uncommon to have a severe allergic reaction.
Finally, a word about another similar condition, latex-fruit syndrome: As many as 50 percent of latex-allergic people are sensitive to certain foods. These foods include avocado, banana, chestnut, kiwi, peach, tomato, white potato and bell pepper. The cause is similar to that of oral allergy syndrome. Some people develop the food allergies first, then the latex allergy follows, and sometimes it occurs with latex allergy developing first.
Contact us if you or your child are experiencing these symptoms and have questions about oral allergy syndrome or latex-fruit syndrome. We’re here to help.