|Many children stop sucking on their thumb or pacifiers around their third birthday. After this age, if he still uses a pacifier or sucks his thumb, you should consider taking action to stop this habit if he is sucking on his thumb/pacifier for most of the day, if it is affecting his communication or social skills, if he is having trouble with his pronunciation of words, or if it is causing problems with his oral development.
Some treatment tips to help your child give up thumb sucking or pacifier use include offering a reward or special treat, begin to limit thumb/pacifier use (first limit use to inside the house, and then put the kitchen off-limits, etc.), taking the air out of the pacifier by poking a hole in it or cutting off the end, replace the comfort of sucking with other comforts (for example, holding his hand when he upset), supply a substitute and keep his mouth busy by singing a song, playing a musical instrument or having a snack, and most importantly, ask your child about giving up sucking his thumb or pacifier and how he would like to go about doing it (slowly vs. cold turkey).
Avoid putting your child down or describing him as being babyish.' Also avoid nagging your child or turning this into a power struggle.