Birch is the primary cause of cross-reactions in people with oral allergy syndrome (OSA), according to Dr. Rachel Eitches. Kiwis, celery, nectarines, apricots and apples are the most common trigger foods. Some individuals with OSA may experience reactions to fresh foods, but not to cooked or canned foods.
For example, if you're allergic to herbs, you may be able to eat tomato sauce on pizza without any issues, but a salad with fresh tomatoes may cause your mouth to itch. Others may find that they can eat certain varieties of fruit (such as Macintosh apples versus Granny Smith) or fruits without skin. Although most oral allergy symptoms will disappear when you stop eating the food, it's always a good idea to consult an allergist for an individual assessment whenever you experience food-related allergy symptoms. If you have seasonal allergies and want to know what other foods can make your allergies worse, up to one in three people with seasonal allergies may have oral allergy syndrome; however, the exact number is unknown as the condition is often undiagnosed.