Oral Allergy Syndrome is an allergic response to certain types of fruits, vegetables and/or nuts that may occur in people who have an existing allergy to tree, weed or grass pollen.
The itchy, watery eyes, or that sudden tingling, itching or burning sensation in your mouth is all too familiar: it must be ragweed season again.

You walk outside, and the summer air is anything but fresh but you endure the symptoms which thankfully start to wane. Later that night, after your soccer game, the juicy watermelon you share with a friend makes your tongue and lips swell. Your stomach is hurting the whole car ride home, and you decide that maybe next time you will have to pass on the watermelon.

But this is strange: you knew you were allergic to ragweed, but your reaction to watermelon is brand new.

Although there is still so much we do not know about allergies, we do know that certain types of foods, or pollen like ragweed, are common culprits when it comes to giving the body an allergic reaction. Put in the simplest terms, allergic reactions happen when a person’s immune system recognizes certain proteins called allergens, as foreign or unsafe. The body’s immune system then triggers an allergic response, like the swelling in your tongue and lips, to fight off the allergen.

Reacting as if allergic

However, some allergies can be much more complex, even downright sneaky.

Oral Allergy Syndrome (OAS) is one such allergy. Certain types of fruits, vegetables, and nuts can trigger OAS but the strange part is you can also develop OAS even if you are not allergic to any of these foods. With OAS, even if you are not allergic to watermelon, you can still have an allergic response when you eat it. A pollen allergy, for example to ragweed, can be activated after eating certain fruits, vegetables, or nuts.

You can react to something you are not actually allergic to because your immune system gets confused. Many of the proteins that cause allergic reactions are very small and similar in structure. The protein molecules that make up the watermelon were mistaken by your immune system for harmful pollen allergens. Your immune system triggers the allergic response to fight off the protein molecules because it thinks they are harmful pollen allergens, like those found in ragweed. Basically, your ragweed allergy and a confused immune system are the reasons you reacted to the watermelon.

If you have an allergy to birch, you can react to apples, carrots, or even almonds. An allergy to mugwort, another type of weed, can give you a reaction to watermelon. These are just a few examples of the fruits, vegetables, and or nuts that can be involved in OAS, a tricky allergy that can make you wonder why removing yourself from a known allergen doesn’t always solve the problem. If you think you might have OAS, speak to your allergist.

This article was written by the registered dietitians at the Specialty Food Shop at Toronto’s SickKids Hospital.

Thank you to AboutKidsHealth.com


Jennifer McCallum

Thank you so much for stopping by this page to get to know a bit more about me and why I started Parent Guide Inc. My business story started a way back in 2001... …after the birth of my first daughter, I realized that an "all-in-one" resource guide for parents was needed, and fast! I designed the New Parent Resource Guide to fill a gap in the community for busy parents like myself. The New Parent Resource Guide offers an A-Z of key contacts for parents, caregivers, service providers, and health care professionals.  Working with key businesses and organizations in the community, we have also compiled much-needed articles, tips, and charts to answer all your parenting questions. The latest addition to our family is the School Age Resource Guide to serve parents of children, 3 to 18 years!  This guide answers questions about: nutrition, bullying, curriculum, building self-esteem, and much more, as well as offering a full directory of local and national resources. The Parentguide.ca website offers an “all-in-one” spot for parents to connect, add their own blog, and find needed resources in their community.  It is a site that educates and entertains and if you can't find somthing just ASK me. I am here to serve YOU!  My hope is that you connect with our members, find comfort in their words, and share your own story. My goal is to see what I can do to help make life a bit easier for you.   You are why I do what I do! I can’t wait to get to know you!  Comment below to tell me about yourself – then start blogging so we can find out what makes you get up in the morning!  Check out my blog too and I am sure you will be surprised what gets me out of bed each day!!! Jennifer -  Mom and Publisher

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