A: Blisters on your baby’s lip are normal and not uncommon. Rest assured, the blister is not painful for your baby. There aren’t any related dental complications. Repetitive sucking of their thumb or frequent breastfeeding may increase the possibility of blistering. Some babies are born with blisters because they sucked their thumb in the womb. Keep breastfeeding as usual, and the blisters should go away on their own, as your baby learns how to breastfeed. This may take a week or so. If the blister does not clear up in 7-10 days you should contact your pediatrician.