How can i stop thumb sucking?

Yours or a child's?: If you're asking about you, just stop sucking your thumb. Try chewing gum. If you're talking about a child, it depends on the age. If it's a baby or a toddler, you can't, so stop worrying about it. A baby who needs to suck will suck, and almost all grow out of it. If it's an older child try a system of rewards for not sucking, like gold stars or a desirable toy.

Age of patient?: Infant: offer pacifier toddler: out of sight, out of mind child: peer pressure, thumb sucking splint (breaks the suction), painting nails with bitter substance specially designed for this teen/adult: habit replacement therapy, plus child treatments.