Thumb sucking is a common practice among infants and young children as a self-soothing technique. It usually involves sticking the thumb inside their mouths but some may use other fingers or the whole fist. Many children find this act to be soothing or entertaining, particularly during the first few months or years of life.

Ultrasound images have shown some babies sucking their thumbs in the uterus. Throughout infancy and the toddler years, thumb-sucking is quite common. It tends to peak around age 2, and most children no longer engage in this habit by 4 years of age. In most cases, thumb-sucking is harmless. However, the practice can cause problems in children who continue to suck their thumbs for long periods of time.

Parents should be concerned if they notice changes in the shape of the child’s mouth or teeth. Other symptoms associated with problem thumb-sucking include chapped lips, cracked skin, calluses and fingernail infections.

Thumb-sucking can become a problem when it continues past the age of 4 years, especially after permanent teeth come in around age 6. Children who continue to suck their thumbs after this point have the potential to develop dental problems if they suck too hard or press on their palate (roof of the mouth) or teeth.

Children who continue to suck their thumbs as they get older are often the target of teasing from their friends and siblings. In many cases, this peer pressure alone is enough to make them stop. Pediatricians sometimes suggest that a parent place a plastic strip or an adjustable plastic cap called a “thumb guard” over the thumb to prevent the child from sucking on it. Over-the-counter agents are available that can be applied to the thumb. These cause a bitter taste when the thumb is sucked.

Thumb-sucking is a childhood habit that often begins before a child is even born and continues for several years afterward. It tends to bring a soothing effect to children, particularly during the first few months or years of life.

All babies are born with a sucking reflex, and thumb-sucking is a habit that grows out of this reflex. Habits are patterns of behavior that are repeated, often without the person realizing it. Like many other childhood habits – including fingernail-biting, nose-picking and hair-twirling – thumb-sucking appears to have a calming effect in some children. In particular, thumb-sucking is believed to have pleasant associations with feedings and the end of hunger. This may explain in part why some children find the habit so hard to break.

Some children may suck their thumbs purely for entertainment. Children who are older may return to sucking their thumb whenever they are under stress or experience other anxieties. Thumb-sucking in response to obsessive thoughts may be an indication that the child has obsessive-compulsive disorder.

The reason why the thumb is sought out more than other digits is a mystery. It appears that random movements by a fetus or infant simply cause the thumb to come into contact with the mouth more than the other fingers. However, some children do go on to suck other fingers, or even their entire fists.

Contrary to common belief, thumb-sucking usually does not harm the development of a child’s teeth or cause an overbite during the child’s first three years of life. In cases of premature birth, there is evidence that thumb-sucking actually helps a child gain weight and reduces a child’s crying.

Thumb-sucking tends to peak around age 2, and most children stop sucking their thumbs by 4 years of age. However, other children may continue to suck their thumbs when they are bored, stressed or otherwise upset.

In most cases, a parent’s best approach to a child’s thumb-sucking is to ignore it. Most children eventually outgrow the habit on their own. However, thumb-sucking can become a problem when it continues past the age of 4 years, especially after permanent teeth begin to come in around age 6. Teasing and peer pressure from friends or siblings eventually convinces many of these children to stop, but others cannot seem to break the habit. Some may quit during the day but still suck their thumbs at night or in private. Children who continue to suck their thumbs for longer periods of time are at risk of developing an overbite if they suck vigorously or press against the roof of the mouth (palate).

Some parents prefer that their child suck on a pacifier rather than sucking their thumbs. A pacifier is a rubber or plastic nipple or teething ring. Pacifiers can be useful tools for young children who have a desire to continue sucking beyond nursing or bottle-feeding.

Parents who use pacifiers should only use them when they are sure their baby is not hungry. Children who are hungry and who receive a pacifier may become upset, which can interfere with feedings. Parents know their children best and are urged to use their judgment about whether or not a child is hungry.

The chief advantage of pacifiers is that many children find it easier to give up the habit of sucking on a pacifier than they do quitting thumb-sucking. There is also some evidence that pacifiers may help prevent sudden infant death syndrome (SIDS).

While thumb-sucking typically is harmless, it can occasionally cause problems, particularly in children who continue to suck their thumbs for long periods of time. Parents should be concerned if they notice changes in the shape of the mouth or teeth. In particular, they are urged to look for changes in the roof of the mouth (palate) or in the way the child’s teeth line up, a problem known as malocclusion. Such problems are most likely to occur in children who vigorously suck their thumbs, rather than those who simply rest their thumbs passively in their mouths.

Prolonged thumb-sucking also can lead to other physical symptoms, including chapped lips, cracked skin, calluses and fingernail infections. In some cases, teeth that become misaligned due to thumb-sucking can lead to speech defects.

Children who continue to suck their thumbs as they get older are often the target of teasing from their friends and siblings. In many cases, this peer pressure alone is enough to make them stop. These children may occasionally revert to sucking their thumbs in private as a means of calming themselves before sleep. In most cases, this is harmless and the habit will disappear over time. However, parents may suggest to their child the idea of wearing a glove, sock or other device that might prevent this type of thumb-sucking.

In some cases, a child will need medical help before stopping thumb-sucking. Pediatricians sometimes suggest that a parent place a plastic strip or an adjustable plastic cap called a “thumb guard” over the thumb to prevent the child from sucking on it. Over-the-counter agents are available that can be applied to the thumb. These cause a bitter taste when the thumb is sucked. However, it is important that the child feel comfortable with these methods. Any treatment that makes a child feel tense, ashamed or afraid should not be used.

Parents who fear dental damage as a result of their child’s thumb-sucking may consider consulting with a pediatric dentist. A device called a palatal bar can be temporarily installed that will prevent the thumb from putting pressure on the roof of the mouth (palate) or teeth. In many cases, children find that this device makes it uncomfortable for them to suck their thumb. Thus, the device can often make children stop sucking their thumb altogether.

Parents can also take steps to help their children stop sucking their thumbs. Parents may attempt to calmly explain why they dislike the thumb-sucking habit and explain why it is important for the child to stop.

Parents are also urged to include their child in the process of breaking the habit by asking for suggestions from the child about what might help them. Children can also be consulted about issues such as how many slip-ups they should be allowed each week, or whether a plan should be worked out where the child gradually stops sucking the thumb during certain activities (e.g., while watching television). Involving children in this way is empowering, making it more likely that attempts to quit thumb-sucking will be successful.

Parents should not punish, ridicule or scold the child, and should never pull a child’s hand from the mouth. This is likely to make the problem worse. Instead, parents should look for positive ways to replace the child’s habit. Sometimes, the simple act of keeping children occupied in enjoyable activities may relieve the boredom that causes them to suck their thumbs. If a parent suggests the change and the child resists, the parent should wait a few months to ask again.

Preparing questions in advance can help patients and parents have more meaningful discussions with their physicians regarding issues such as thumb-sucking. The following questions related to thumb-sucking may be helpful:

1. When should I become concerned about my child’s thumb-sucking?
   
   
2. What are the signs that my child is actively sucking his/her thumb, rather than letting it passively rest in the mouth?
   
   
3. We’re about to move to a new home – should we delay trying to get our child to stop sucking his thumb?
   
   
4. What signs should I look for that might indicate damage to my child’s palate or teeth?
   
   
5. What are the benefits of thumb-sucking for my child?
   
   
6. Should I consider a pacifier for my child? What are the pros and cons?
   
   
7. How can I encourage my child to cease thumb-sucking after the age of 4?
   
   
8. Should I use an over-the-counter agent to make my child’s thumb taste bitter?
   
   
9. Would my child be helped by a palatal bar?
   
   
10. My child still sucks his thumb at night. How will I know if that becomes a problem?
    
    
11. I think my child is sucking her thumb because of stress. How can I help her relieve her fears?