• itchyeater

What is Oral Allergy Syndrome!?

Updated: Mar 29, 2020

Disclaimer: I am not a medical doctor, allergist, or dietitian. The information on this site recounts my personal experience only. Talk to your doctor with questions or concerns. I post links to items I use or recommend. I am not affiliated with these companies and do not receive compensation if you click on the links. I use links for reader's convenience.

What is OAS?

Through my experienced and what I have read, individuals are not born with OAS and more likely grow into it either in late childhood or adulthood. It is related to an individual’s seasonal allergies (e.g., ragweed, birch, grass).

OAS is a cross reaction from food proteins and pollen that is found in fruits, vegetables, and tree nuts. For example, if you are allergic to birch then you might be allergic to apples, almonds, carrots, celery or any foods related to birch. OAS is a contact allergen and not an airborne allergen; meaning that a person can be in the same room or within close proximity to the food but they cannot eat and sometimes even touch a food.

This image is from Allergic Living

I have read that if you cook the food item then you are changing the chemical makeup of it and likely eliminating the protein, which then makes it “safe” to consume. I know from first hand experience this is not always the case. I cannot eat zucchini, eggplant, or squash raw OR cooked.

What Causes OAS?

A confused immune system?

Apparently the food contains certain proteins which our body may confuse for the pollen and then react to it. Above is an image of common cross-reactors.

What are the Symptoms?

For me, itching around the lips/mouth (this can occur from touching an item, kissing my boyfriend who ate something, a factory cross-contamination, or for absolutely no good reason at all). Hives may develop inside of my mouth or throat if I eat the food directly.

Itchy mouth, lips, and tongue are the most common symptom, while anaphylaxis is rare. I thought one time my throat was closing up, though in fact it was hives developing on the inside; there was still plenty of room for me to breath (doctors said it was mostly mental!).


Avoid all foods you react to!

This is easy to say and hard to do.

We’ll get into the nitty gritty of that at another time.

For more information on Oral Allergy Syndrome, I have included some links below that I have moderately helpful and mildly not helpful. Meaning, it’s way easy to read about something compared to living your life.


The American College of Allergy, Asthma, and Immunology

American Academy of Allergy, Asthma, and Immunology

The Children’s Hospital of Philadelphia

Allergic Living

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