M.A.
My youngest sucked her thumb until she was 3 or so. The dentist told me she needed to quit but I could not do it. Finally I put hot sauce on both thumbs. I told her if I caught her thumb in her mouth she would get more. Never had to put anymore on her after that. She hates hot sauce. If you do not feel comfortable with it I understand it made me cry and I had to leave the room when I did it. If she hates something else us it. Like I hate peas. SO put peas on my thumb and I would not like it. Find what she hates.