After my 1st week of vaping I noticed some mouth sores, at 1st thought PG must be bad for ya (lmao, yea hilarious I know) then I got a suggestion that it might be our local ching chong liquids(Chinese). Spoke to a mate of mine today who has quit smoking cold turkey, he had the same problem when he left the stinkies. Doc told him that it is very common when quitting cigs as your immune system takes a heavy blow. So mates, conclusion? The Chinese is not out to get us, nor is PG a Illuminati plan to take us out......Vape on!!! Mouth sores is a reminder of the chemical dosing you have left behind when throwing that 20pack out.