I have this! I have Birch Oral Allergy. The specialist in London tested and I'm allergic to birch trees (and most others), my body mistakes the fruit proteins for birch proteins, my lips, tongue, throat swell up/close. There aren't many that don't cause this but thankfully, oranges, bananas and strawberries don't, they're my favourites!
I have a great test the doctor told me to do. I rub the inside of my bottom lip with whatever I'm eating, if it doesn't tingle/swell, I try a little on my tongue. If that doesn't tingle/swell, I swallow a little bit. If my breathing's not affected, then I eat it. I love this test, it's saved me a few hospital trips - or worse.
I develop new allergies all the time, at least one a year, including to things I've been fine with for a long time. The specialist told me that's normal. He also said that the most common time for your body to reject something isn't the first time you try it, it's the second or third time. Your body often says `I don't know this´ the first time. Ìt then switches to `I know this, I don't like it´mode.
The other great tip he gave me was to test things on my inner wrist, not just once but three times within 24 hours. He said once isn't always enough if your body doesn't know it. If something isn't a cream, etc, he told me to see if I could make a concentrate in water.
