Why do children suck their thumbs?
Sucking is an innate reflex in infants. Fetuses even suck their thumbs in the womb! Babies begin to understand the world by first exploring their own bodies. They often use their mouths to explore body parts like their hands and toes, which may be unconscious. They also suck their thumbs when hungry, using the sucking motion to soothe themselves. This behavior gradually evolves into thumb-sucking when they feel nervous, need comfort, or are bored. Thumb-sucking is a common habit among children, and the American Academy of Pediatrics estimates that about half of children suck their thumbs before age four.
Since infants and toddlers usually suck their thumbs unconsciously or for self-soothing, parents don’t need to deliberately stop them or make fun of them. As children grow, they develop other ways to comfort themselves and become aware of others’ opinions. This habit typically disappears once they start school.
However, if a child frequently sucks their thumb beyond age four or five, it may affect the shape of their jawbone and the alignment of their permanent teeth. After permanent teeth emerge, vigorous thumb-sucking or strong tongue thrusting can cause dental deformities, leading to malocclusion or buck teeth, which may affect appearance. If thumb-sucking becomes a frequent and persistent habit, the thumb may become red, and the skin may crack—especially around the nail—causing pain, sensitivity, or even sores that are vulnerable to infection or inflammation. In such cases, parents need to help their child reduce this behavior.
What can parents do?
1. If the child’s thumb becomes red or cracked from sucking, apply moisturizer while they sleep.
2. If you notice the child using this behavior to self-soothe due to anxiety, try to identify their feelings and verbalize them. For older children, patiently ask them to express their emotions. Strengthen their sense of security through closeness and communication to ease their worries. Distract them with toys or activities. Teach older children relaxation techniques like deep breathing.
3. If they only suck their thumbs when bored, provide activities to keep their hands busy, such as playing with toys, holding a soft doll, holding your hand, or helping carry items.
4. Briefly and clearly explain why you want them to stop (e.g., “Mommy hopes you stop sucking your thumb because it’s unhygienic”). Stay calm—avoid scolding or punishing.
5. Teach the child “habit reversal”: suggest a conflicting action to replace thumb-sucking. Gently remind them to do this instead (e.g., wiggle fingers like playing piano, pinch their nose, or count to 20 on their fingers).
6. Reward the child with a sticker and verbal praise each time they successfully resist the urge. Use a behavior chart to track progress; accumulated stickers can be exchanged for a favorite activity.
7. If the child uses this behavior to seek attention or to defy you, the best approach is to withhold attention—don’t look at or speak to them until they stop. Consistently doing this will make the behavior less appealing to them.