In hay fever, the immune system treats pollen as a foreign invader. It prompts sneezing, runny nose, watery or itchy eyes, and other unpleasant symptoms to flush the intruder out of the body.
In oral allergy syndrome, your immune system treats proteins similar to those in pollen that are sometimes found in fruits or vegetables the same way. It's as if it says, "Close enough!" and attacks it. That's called cross-reactivity.
Foods to Watch Out For
Ragweed Allergy: "Ragweed, in theory, cross-reacts with bananas and melons, so people with ragweed allergies may react to honeydew, cantaloupe, and watermelons, or tomatoes," says Warren V. Filley, MD, from the Oklahoma Allergy & Asthma Clinic in Oklahoma City.
Zucchini, sunflower seeds, dandelions, chamomile tea, and echinacea also go on that list.
Birch Pollen Allergy: People with birch pollen allergies may react to kiwi, apples, pears, peaches, kiwi, plums, coriander, fennel, parsley, celery, cherries, carrots, hazelnuts, and almonds.
Grass Allergy: People with grass allergy may react to peaches, celery, tomatoes, melons, and oranges, according to the AAAAI.
Latex Rubber Allergy: Like pollen allergy, people allergic to latex rubber may react to bananas, avocados, kiwi, chestnut, and papaya.
Oral Allergy Syndrome Test
Hannelore A. Brucker, MD, of the Southdale Allergy & Asthma Clinic in Minneapolis, often asks her allergy patients about possible oral symptoms.
"I ask if they have itching in the mouth when they eat apple, and if they say 'No' and then I see a skin test and it’s high-positive for birch, I ask again," says Brucker.