Have you ever experienced itchy mouth after eating raw fruits or vegetables?
Oral allergy syndrome, also known as pollen-food syndrome, is caused by the cross-reaction of proteins in pollen with raw fruits, vegetables, or tree nuts. Many of the proteins found in these foods are similar to pollen proteins confusing the immune system and increasing allergy symptoms. Oral allergy syndrome is a contact allergic reaction occurring when the offending food touches the mucosa (lining) of the mouth or throat causing itchy mouth, swollen tongue or lips, and scratchy throat. These symptoms are usually mild and usually resolve once the food is swallowed.
Oral allergy syndrome may appear at any age, even if you have been consuming these foods for years without problems. Oral allergy syndrome is diagnosed after a patient is skin tested and the test shows positive allergy to pollen, and they experience these symptoms after ingestion of one of these foods.
Many people with oral allergy syndrome can tolerate these fruits and vegetables if they are cooked as this changes the structure of the protein. Other options are peeling the skin. Many times the skin contains high concentrations of the protein that causes the symptom. Avoiding the food especially during the peak pollen season can also prevent these symptoms.
Consult an allergist if these symptoms are experienced with ingestion of tree nuts or cooked fruits or vegetables. Symptoms such as skin rashes, nausea or vomiting, difficulty breathing, or if the reaction is beyond the mouth could be considered a life threatening reaction called anaphylaxis which requires immediate care.
Below is a list of pollens and the foods with cross-reactivity:
Birch Tree: apple, apricot, cherry, peach, plum, pear, kiwi, carrot, celery, parsley, peanut, soy, almond, hazelnut
Timothy/Orchard Grass: peach, watermelon, orange, tomato, white potato
Ragweed: cantaloupe, honeydew, watermelon, banana, cucumber, white potato, zucchini
Mugwort: bell pepper, broccoli, cabbage, cauliflower, chard, garlic, onion, parsley, caraway, coriander, fennel, black pepper