Be wary.. lip plump crayon. I've just got home and mindlessly tried this out thinking it was a normal lip crayon. My lips started burning!
Closer inspection showed it was a lip plumping "and tingling" crayon and that reviews on the boots website said the same about the burning sensation. I wiped it straight off but just wanted to put it out there as most odd! Burning went off after a few minutes (disappointed as colour was nice!).