As a juniour doctor in Accident and Emergency MANY years ago I once had a patient come in to casualty at 3 am. This was in the middle of winter in the busiest ER in the whole of London when we were stretched to the seams. I was in between the Heart Attacks and the Traumas. I was dead tired and needed a break. At the time we had a thing called a “4 hr wait time” which meant no patient should be kept waiting more than 4 hrs to see a doctor. This patient looked really well so was at the bottom of the pile but he was about to “breach” or cross the 4 hrs so the matron was nagging me to see him.
So, I picked up his file and asked him how I could help. I was slightly annoyed when I heard his complaint: “Doc whenever I eat Watermelon my mouth tingles”
“Anything else happen? Any shortness of breath? Any hives?” I asked, my irritation mounting at the fact that this was neither an Accident nor an Emergency.
“No, not at all.. but sometimes my lips feel slightly swollen…what should I do?”
“Stop eating Watermelon” I replied, shortly, even before I could stop myself. He looked a bit taken aback, and I thought he was a bit mad….
“What, you aren’t going to give me anything for it?” he demanded.
“Nope!” I said and I promptly discharged him – one minute before he breached his four hour wait.
Now I know better. He was not mad. He was describing something called “Oral Allergy Syndrome” which at the time I knew nothing about….But at least, now that I know more, although I am slightly ashamed of my terse response, I know that the treatment I prescribed ie “Stop eating Watermelon” was the right one.
So what is Oral Allergy Syndrome?
Some people develop antibodies to usually harmless things in the environment like specific pollens/moulds/grasses etc. So, when we breathe in the pollen for example, we get an allergic reaction happening in our nasal tract and eyes and sometimes lungs causing, itchy watery eyes, runny nose and itchy throats. Sometimes we can even get wheezing. Hay fever is another term for seasonal rhinitis (runny nose). because it only occurs SEASONALLY when the pollen you are reacting to is in the air.
Lots of fruits/plant based foods may have proteins in common with the pollen you are allergic to. So, if you get Hay Fever in response to certain pollens you may also get symptoms of something called Oral Allergy syndrome or “Food Pollen syndrome” when you eat certain raw fruits. This is called a “Cross reaction” Oral allergy syndrome is called “oral” because the symptoms occur around or in the mouth ad rarely cause systemic effects like a drop in blood pressure or diarrhoea or widespread itching. The symptoms often start within a minute or so of eating the fruit and goes away on its own in a couple of hours….but it can be scary.
A similar cross reaction can happens with people who are allergic to Latex. Some fruits have proteins that are similar to Latex (Latex comes from the rubber tree) and they can develop an allergy to certain fruits and nuts: Particularly Bananas, Avocado, Pawpaw, Celery, Apples and Kiwi fruit and Chestnuts. This is called “Latex Fruit syndrome” or “Latex Fruit Allergy”. So if you get itching when you use latex condoms and your lips swell when you blow up a ballon or eat bananas, I now know you are not mad… you have Latex Fruit Syndrome. Sometimes the symptoms with this CAN be more systemic like hives. and rarely a severe reaction called anaphylaxis with swelling of the throat and difficulty breathing and a drop in blood pressure.
By the way, people who get oral allergy syndrome with Watermellon, are likely to get Hayfever with something called Ragweed.
However other fruits may be associated with grass pollen, birch pollen and others. The list is long! The point is, if you suffer with Hay fever or seasonal rhinitis and you have noticed symptoms of oral allergy syndrome when you eat certain raw fruits then you know what you have to do… stop eating them! Or, you can try cooking them, which denatures the protein that you are reacting to.
More systemic reactions like anaphylaxis are rare.
If you think you may have Oral Allergy Syndrome keep a food diary and come in. There are blood tests that can be helpful. May is Asthma and Allergy Awareness Month and to raise awareness we’re offering 10% off any allergy or asthma consultation for the next 4 weeks.
For a list of common cross reactions see this helpful website: https://www.allergyuk.org/resources/oral-allergy-syndrome-pollen-food-syndrome-factsheet/