Thumb sucking is a common comforting habit in younger children. Because a baby’s desire to suck their thumb is essential for life, Dr. Cindy Gellner actually discourages trying to stop thumb sucking during the first few years before permanent teeth come in, usually around 4-5 years of age. But thumb sucking into a child’s school years can lead to behavioral issues. For children who refuse to let go of their thumb sucking habits, Dr. Gellner has some tips on how to get them to stop.