The misery teething sometimes causes your baby to endure can break your heart. Teething can begin as early as 3 months, said Dr. Elizabeth Athans of the department of pediatrics at Nemours Children’s Hospital. “For some babies, teething is painless and for others, it can be very painful, with brief periods of irritability, crying jags and disrupted sleeping and eating patterns.” Comfort and soothe your baby with tried-and-true teething remedies designed to turn those frowns upside down.