It is normal for babies to suck. It gets them food and helps them relax.
By the time your child is 2 or 3, he or she has less need to suck. If your
child still likes to suck, a soother is better than sucking a thumb. Why?
Because you can control when and how your child uses a soother. You can't
control a thumb going into the mouth.
Never put sugar, honey or corn syrup on a soother. They can cause cavities.
It's best to get your child to stop sucking before permanent teeth come in,
at about age 5. If a child keeps sucking a soother or thumb after the
permanent teeth have come in, this could cause problems with how the jaw and
teeth grow.