Thumb sucking is normal in infants and young children. It shouldn't cause any permanent problems if your child stops by age 5.
Thumb sucking is one of the most common habits of children. The habit starts early in life, with 90 percent of newborns showing some form of hand sucking by two hours of age.
Thumb sucking is normal in infants and young children and should cause no permanent problems if it is not continued past the age of 5. Likewise, it is generally harmless for infants to use pacifiers.
The American Academy of Pediatric Dentistry states that most children stop thumb sucking on their own between the ages of 2 and 4. The Academy states there is no reason to be concerned until the front teeth start erupting. At this point, some problems may occur, including bite problems, or protruding front teeth. Other problems that may occur with thumb sucking are sore thumbs, infections, and calluses on the thumb.
It is thought that pacifier use may actually be better than thumb sucking for the following reasons:
Pacifiers are softer and cause less damage to the teeth.
The plastic rim on the pacifier provides some relief of the tension placed on the teeth.
Pacifiers can be cleaned.
Consult your child's physician if you are concerned with your child's thumb sucking. Generally, it is not a problem for children under the age of five.