I was also reading about cross sensititivies, as I'm allergic to a few things (mugwort for example). I'll see a dermatologists who also does naturopathy and allergy next week and see what she thinks. I don't know if they are able to test what cross sensitivities I really do have, because doing an Elimination Diet wouldn't work that well, as I could eat most of what I eat now :) Also, I'm not sure if such a reaction would only be on the lips. I would think that as the proteins are similar, I should also get similar symptoms, but I might be wrong.