Reputable juice vendors disclose their ingredients. As said, Pharma grade mixes should be ok. I don't know what kind of nut allergy you have, but I do know a lot of VG is made from coconuts. If you need to vape to quit, or even just want to, you may eventually wish to DIY your own juice so you know exactly what is in it and will have no problems. I DIY myself-- for me it's because so doing makes juice about 10% of the retail cost-- and it is no harder than following the recipe on a cake box, although tweaking the recipe to get the exact flavor you want can be a time consuming trial and error process.
Welcome to the board.