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.
Recommended Related to Allergies
Oral sensitivity tends to develop over time, with repeated exposures to pollen. Brucker says most of her patients with oral allergy syndrome are in their 20s and 30s.
Filley's advice: See a board-certified allergist. "It could be oral allergy or could be something more serious," Filley says.
You may get a skin-prick test. A bit of the suspected trigger goes on a light scratch on your back or forearm. If that spot turns red or swells in about 15 minutes, it's an allergic reaction.
Next, the doctor has to analyze the problem. "Either this is mainly oral allergy and not to worry, or this could be more serious and [you need to] take more precautions, such as carry epinephrine with you," Filley says.
A recent study shows that in about 2% of people with oral allergy syndrome, oral allergy symptoms could progress to anaphylactic shock, which could be deadly without immediate treatment like an epinephrine shot (Auvi-Q, Epi-Pen).
Don’t Eat Trigger Foods
The basic rule: If a food makes you uncomfortable, don’t eat it.
If it’s a favorite food, try these tips:
Cook it. Cooking often breaks down or alters the trigger proteins so that the immune system doesn't target them.
Peel it. Peeling fruits such as apples may help, because most trigger proteins are in the peel.