Pacifiers do not harm babies.  As a matter of fact there is some evidence that pacifiers reduce the risk of Sudden Infant Death Syndrome SIDS.

How to use a pacifier safely

• Do not use the top and nipple of a baby bottle as a pacifier even if you tape  them together. The nipple can pop out  of the ring and choke the baby if she sucks hard.
• It is important to choose a pacifier that is molded as one solid piece of plastic. These are safe to use. You can ask your pediatrician for recommendations.
• Never tie a pacifier around your child’s neck or to his crib. This is dangerous and cause serious injury and death.
• The shield between the neck and the nipple should be at least 1-1⁄2 inches (3.8 cm) across. This is important so that the child cannot put the entire pacifier in her mouth. The shield should also be made of firm plastic with ventilation holes.
• Replace your pacifier if the color is worn out or torn. You also have  follow the recommended age range because older kids can fit an entire newborn pacifier into their mouth.