How to Tell Oral Allergy Syndrome from Food Allergies

What Are Food Allergies?

Most people are able to recognize food allergies when they cause difficulty breathing, hives, and other signs of anaphylaxis. But what if certain foods just make your mouth itchy?

So this is a topic I know way too much about. As someone with the classic atopic triad of allergies, asthma, and eczema, my immune system thought it would be fun to add a bunch of food allergies as well.

Now, while eating the tiniest bit of guacamole makes me look like a movie star who had a bad Botox job and sound like I have been smoking for decades before my throat actually starts to close off and I start wheezing, that's not what I'm going to talk about today. That is a true anaphylactic reaction, what most people think about when they hear that someone's allergic to a particular food.

What is Oral Allergy Syndrome?

Oral allergy syndrome is more like what I get when I eat apples in the springtime. My mouth gets all itchy, but it goes away without me using my epinephrine. So what's the difference?

Pollen Cross-Reactivity

The American Academy of Allergy, Asthma, and Immunology, the AAAAI folks, define oral allergy syndrome as a type of contact allergic reaction that happens with raw fruits and vegetables. It causes reactions pretty much immediately after eating uncooked fruits and vegetables. And the main symptom is itching and swelling of the mouth, face, lips, tongue, and throat. This is because of cross-reactivity with pollen. Oral allergy syndrome is sometimes called pollen fruit syndrome for this reason.

Raw Fruits and Vegetables Trigger Most Symptoms

People who have seasonal allergies triggered by pollen have this because the proteins in some fruits and vegetables are very similar to those found in pollen. The AAAAI reports that up to 75% of adults who are allergic to birch tree pollen have reactions to apples or celery. And I just happen to be one of those lucky people. It can happen to people who have grass or fall ragweed allergies, too. People who are allergic to grass can have reactions to peaches, tomatoes, melons, and oranges. People with ragweed allergies can have these symptoms with bananas, cucumbers, melons, and zucchini.

Cooking Foods Can Reduce Reactions

Notice I said that it happens when people eat raw fruit and veggies. One way people can reduce these reactions is to cook the foods because high temperatures break down the proteins that the body is reacting to. That's why I can't even touch the inside of a raw tomato without breaking out in hives, but I can eat tomato sauce on pasta.

Another way to decrease the reactions is to eat the foods only during the time of year when the pollens responsible for their reactions are low. For example, I can't eat apples during the spring, but I can in wintertime because there's no birch pollen floating around.

When to See an Allergist

Unfortunately, there's no specific test for oral allergy syndrome, and there's not a cure either. What I tell parents is that if you know your child has a reaction to a specific raw food, then avoid it during pollen seasons. Sometimes, if a person is really bad, an allergist can do skin tests to look for specific pollens and then correlate that to the person's food reactions.

If your child has a reaction, then giving them an antihistamine will help with that particular reaction, but avoidance is really the key. If your child has reactions to several different foods or has anaphylaxis symptoms to food, then it might be time to discuss a referral to an allergist for your child to see what they are allergic to.

_{updated: August 19, 2025
originally published: October 7, 2019}