Guest Post: The Time I was Diagnosed with Oral Allergy Syndrome

When I was 8 years old, I was at a family get-together and fruit was being served. I was happy to see watermelon on the large platter, as it was my favourite fruit. I grabbed a piece and took a bite. Suddenly I noticed something didn’t seem right. Something didn’t feel right. My lips started to burn and itch, something I had never experienced while eating watermelon, or any food for that matter. After a few minutes, the tingling feeling didn’t subside, but rather increased. I went to the washroom and saw that my lips had a red rim around them and were starting to swell. When I returned to my mom and told her what had happened after eating the watermelon, she (like me) was confused. She proposed that it could be an allergic reaction, but to a fruit? It didn’t seem to make any sense. The following day, she called the allergist and booked an appointment to speak about what had happened.

And like my mom thought, my allergist suspected it was an allergic reaction. To confirm our suspicions, he administered a skin-prick test to check for any reactions to seasonal and environmental allergies. I was told I needed to wait a while for the test to be complete, but a few pricks on my arms were extremely itchy and red. Upon completion, he explained that I was reacting the most to birch and ragweed pollen.

My allergist began reading out a list of fruits and vegetables asking if I had experienced this sort if feeling to any of them in the past. When I told him I didn’t think so, he told me that it is very likely that one day I’ll develop sensitivities to them as well. He explained to me that it was likely that I had Oral Allergy Syndrome (OAS), which is also known as Pollen-Food Syndrome. This type of food allergy is quite different, as certain foods are related to the environment and specific pollens. He helped me understand that it is like mild food intolerances that affect your mouth and oral region. What’s interesting about OAS in my case, is that I can eat the cooked version of some of the raw fruits and vegetables that I’m allergic to. This is because the heating process destroys the proteins, making the immune system no longer recognize the food (Source: Though people with OAS usually have a mild reaction, it can however, though very unlikely, become anaphylactic, so I carry an EpiPen® with me every day just in case of an emergency.

Since the day I first experienced an allergic reaction, over 10 years ago, like my allergist anticipated, I have developed many more allergies to fruits and vegetables that are within the birch and ragweed oral allergy families. I have learned through my experiences to strictly avoid any foods that bother me. What’s interesting to me is that after speaking to others about this syndrome, many people are shocked to learn about the possibility of being allergic to something other than the most common food allergens. Even as someone who is living with this syndrome, I truly believe that the conversation around it is lacking in the greater conversation of food allergy awareness. I hope my story begins to shed light on OAS so that others may learn and understand what this type of allergy entails. If you also have OAS, I would love to hear about your experiences in the comments below!

– Simone D.

6 thoughts on “Guest Post: The Time I was Diagnosed with Oral Allergy Syndrome”

  1. I have OAS as well, I was actually diagnosed prior to having any reactions, when they were sorting out my asthma. We have a very strong family history of OAS on both sides of the family.

    It was all mild until 2010, when I started developing anaphylaxis to some of my OAS allergens, and added new OAS allergens. Unfortunately for most of my OAS allergens I react whether they are cooked and raw, but interestingly my skin prick tests are only positive with the actual fruit/veg, and not the extracts.

    I’ve been told that my case is extremely rare, and have heard it’s only about 4% of OAS sufferers who have serious reactions. Everyone else in the family has much milder reactions, and my aunt even managed to grow out of it, after 40 years of avoidance! So there is some hope 🙂

  2. I’m allergic to wheat, and I believe my allergy to grass pollen is the reason. I tested negative on skin and a very low positive on blood to wheat, but my tests for grass pollen were very highly positive. The positive tests for grass pollen weren’t surprising as I had a horrible time with hay fever growing up. I don’t get any kind of oral symptoms from my reactions to wheat, however. Other than the test results, I wonder if everything about my wheat allergy looks more like what some would call a true IgE food allergy. I also carry Epi-Pens, but I’ve been able to use antihistamines like Benadryl and Zantac to treat my symptoms to this point.

  3. I also have OAS. They developed when I hit puberty almost thirty years ago. I can eat some of the foods if cooked first, but the majority of the foods I am now severely allergic to and they continue to get worse over time. I am very careful, but the challenge lies in the exposure through cross-contamination.

  4. I too have OAS. When I was 7 or so I noticed my lips swelling and itchy mouth and inside my ears when I ate raw carrots, celery or apples. It wasn’t until I was 17 and ate dinner at a friend’s house that I had an anaphylactic reaction to cooked vegetables. While I was in emerge the doctor that was treating me spent most of his time arguing with my mom that there is no way vegetables did this to me. (This is 23 years ago). As my mom is a nurse and worked at the same hospital, her next shift the doctor came and apologized as he did some research after meeting me. After that reaction I went for allergy testing. I’d always had a lot of environmental allergies and during testing I reacted to practically everything. Now for the past 23 years I strictly avoid all pitted fruits, all mugworts (carrots, celery, all green herbs) which are part of the birch pollen, timothy grass and ragweed families. I also avoid mangos, avocados, shell fish and latex. I’ve had 3 anaphylactic reactions due to hidden allergens such as herbs and mango. I definitely don’t classify my allergies as OAS. Still to this day doctors can’t believe I’m allergic to carrots!

  5. I also have oral allergy syndrome and when I hate it when I tell people about it, because it’s not well known, they look at me like I am making it up. I recently had a baby and in hospital, when asked about allergies, they had no idea what it was (the same hospital which diagnosed me).

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