Up to what age is thumb sucking normal, and how does it affect teeth and speech? Age-based ways to support an older child who still sucks their thumb.
Many parents first see their child sucking their thumb on an ultrasound screen and treasure that image with love. A few years later, the same thumb is still in the mouth while watching cartoons, while dozing in the car or while the teacher reads a book; this time the image is not sweet but worrying. The dentist says the teeth are being pushed forward, the grandmother suggests pulling a sock over their hand while they sleep, and the child visibly tenses every time you pull their hand out of their mouth. Thumb sucking is one of the oldest and most common ways children soothe themselves. In this article we look at why this habit is so powerful, up to what age it is reasonable to wait, and how you can support a child who still sucks their thumb as they grow older, without forcing them.
Why Does Thumb Sucking in Children Happen?
The sucking reflex is one of the first skills a baby develops in the womb. After birth, sucking does not only provide nourishment; it soothes the baby, reduces tension and eases the transition to sleep. The thumb is the first tool with which a baby can meet this need on their own.
Unlike a dummy, the thumb is always within reach. It doesn't fall, it doesn't get lost, and it doesn't need an adult to hand it over. This makes the thumb extremely useful in infancy, but turns it into a habit that is hard to give up in later years. It is possible to put a dummy in a box one day and say goodbye; but the thumb is always with the child.
In many children this behaviour comes together with another soothing behaviour: rubbing the edge of a blanket with one hand while sucking the thumb of the other, tugging at an earlobe or winding hair around a finger. This pairing forms a powerful habit chain that sends the child's brain the signal "now it's time to relax".
Up to What Age Is Thumb Sucking in Children Normal?
In infancy and the toddler years, sucking the thumb is very common and a developmentally expected behaviour. A large proportion of children reduce or give up this habit during the preschool years, often by themselves and without anyone noticing. Joining a group of friends, hands being busy with play and the development of the ability to express themselves naturally support this process.
The period that needs attention is the age at which permanent teeth start to come through. Dentists warn that intensive sucking that continues in this period can affect the alignment of the teeth and the structure of the palate. What matters here is not only age but the form the habit takes:
- Frequency: Is it only for a few minutes while falling asleep, or at every opportunity throughout the day?
- Duration: Does the thumb come straight out again once it goes into the mouth, or does it stay there for hours?
- Intensity: Does the thumb rest passively in the mouth, or is there strong, audible, rhythmic sucking?
A five-year-old who keeps their thumb in their mouth briefly while falling asleep and a seven-year-old who sucks vigorously throughout the day are not in the same situation. For an assessment specific to your child, your dentist's opinion will guide you.
Possible Effects of Thumb Sucking
Long-lasting and intensive sucking can lead to the following effects in some children:
Teeth and palate: Changes such as the upper front teeth being pushed forward, the upper and lower teeth not meeting at the front, or the palate narrowing may be seen. When the habit is given up early, some of these changes may correct themselves; when it goes on for a long time, an orthodontic assessment may be needed.
Speech: Changes in the tongue and tooth structure can affect how some sounds are produced, especially sounds such as "s" and "z". A thumb that stays in the mouth all day also reduces the child's opportunities to talk.
Thumb health: Calluses, cracks, redness and sometimes infection can be seen on a thumb that is constantly wet.
Social effects: At school age, this habit may attract the attention of peers. A child seen sucking their thumb while dozing on the school bus becoming a target of teasing can lead to shame and hiding. A hidden habit, in turn, is usually not given up; it simply becomes invisible.
Effects within the family: Constant warnings can lead to small conflicts between parent and child repeated throughout the day. In large families, everyone stepping in with their own suggestion, for example an aunt slapping the child's hand or a grandfather teasing them jokingly, magnifies the child's shame about it. Parents agreeing on a shared stance between themselves and asking other relatives to follow it too reduces the pressure on the child.
Why Hasn't My Child Stopped Even Though They're Older?
A question parents often ask is why their child keeps sucking their thumb even though they have reached school age. There are several possible reasons:
The habit has become automatic. Many children don't even notice that their thumb is in their mouth. In front of the television, when bored or when tired, their hand goes to their mouth by itself.
It serves an emotional function. During periods such as the birth of a sibling, starting nursery, parental separation, moving house or tension at home, a child may return to the oldest soothing method they know. A habit that had been given up starting again is also common after such changes.
Warnings have strengthened the habit. For a child who is told "Take your hand out of your mouth!" every time, the behaviour can turn into a power struggle with the parent. As tension rises, the child's need to relax also rises, and the cycle feeds itself.
The child doesn't want to stop yet. This is perhaps the most important point. A preschool child does not yet understand why the habit is a problem. The motivation to stop often comes at school age, with peers' awareness or through the child's own wish.
How to Stop Thumb Sucking in Children: An Age-Based Approach
Children under three
Intervening in the habit is generally not necessary at this age. Respect the child's need to soothe themselves, and teach them to calm down in other ways too, such as cuddling, rocking and lullabies. Observing the moments when sucking increases is enough. It is also not surprising for the habit to increase for a while in a child who has just started nursery or a childminder; they are looking for something familiar to hold on to in the new environment. During this period, asking the teacher or childminder to sit beside the child and keep them company rather than telling them off supports the settling-in process.
Between three and five
Gentle limits can be set in this period. Rather than banning the behaviour, steering it towards particular times and places works: "Your thumb is with you when you sleep; in the daytime our hands are busy playing." Activities that keep the hands busy, such as play dough, jigsaws, colouring or finger puppets, reduce the opportunities for the thumb to go into the mouth during the day. Giving the child a soft toy to hold while watching television is also a simple but effective approach.
Stories are also a powerful tool at this age. Picture books about an animal character who gives up sucking their thumb, or a story you make up together with the child, show them a way forward without blame.
Five and older
For children approaching school age, the key to the process is the child's voluntary participation. At a calm time, talk without judging: "Our dentist said your thumb is pushing your teeth. What do you think? Would you like to stop?" If the child is willing, make the plan together:
- Find the triggers together. When does the thumb go into the mouth most? In the car, in bed, in front of the television? The child's own observations help them take ownership of the plan.
- Agree on a secret signal. Instead of a telling-off, a reminder only the two of you know, such as gently touching their ear, helps the child notice without being embarrassed.
- Decide on night-time together with your child. Because some children suck their thumb in their sleep without realising, a thin cotton glove, a plaster or a pyjama sleeve can work as a reminder while they sleep. However, this should only be done with the child's agreement and using a method they choose; if it is perceived as a punishment, it backfires.
- Make success visible. Putting a mark for every night without sucking on a chart such as a "thumb rest calendar" makes progress concrete. An activity you do together when a certain goal is reached can be more meaningful than a material reward.
During the process of stopping, the child may return to the old habit from time to time. This does not mean the process has failed. Temporary increases should be expected, especially during illness, tiredness or stressful periods.
Approaches to Avoid
Some methods both don't work and make the child feel bad about themselves:
- Forcibly pulling their hand out of their mouth or slapping their hand: This makes the child feel they have lost control over their own body and increases anxiety.
- Putting chilli, vinegar or bitter nail varnish on the thumb: Done without the child's agreement, these practices are perceived as punishment. Bitter-tasting products should only be considered at the child's own wish, as a reminder and on a doctor's recommendation.
- Frightening them: Words such as "Your thumb will rot and fall off" or "Your teeth will fall out" can create bodily anxieties in a child.
- Mocking them and telling others: Saying in front of guests, "This big girl still sucks her thumb," increases shame and hiding.
Telling a child who sucks their thumb to "stop" is easy; our real work is showing them what else they can do when they are bored, tired or scared.
Imagine a six-year-old boy who, after starting school, tells his mother he wants to give up this habit because his classmates tease him as a "baby". Mother and child make a plan together: during the day, when his hand goes to his mouth, he will squeeze a ball of play dough, and at night he will sleep with a superhero-patterned plaster he has chosen himself wrapped around his thumb. Every morning they check together whether the plaster has stayed dry. The first week has a few unsuccessful nights, but because the child built the plan himself he doesn't give up, and within a few weeks the habit decreases noticeably.
When Should You Seek Professional Support?
In the following situations it can be helpful to talk to a specialist:
- If thumb sucking continues intensively at school age and the child cannot stop even though they are willing
- If the habit restarted or increased markedly after a loss, parental separation or a frightening event
- If the habit is accompanied by other signs such as anxiety, sleep problems, angry outbursts or social withdrawal
- If the child is being excluded by peers because of the habit and is experiencing intense shame
- If the child is also showing other repetitive behaviours such as nail biting, hair pulling or skin picking
For changes to the teeth, an assessment by a paediatric dentist or orthodontist is needed; for sores and infection on the thumb, an assessment by a paediatrician is needed. For broader information on repetitive behaviours, take a look at our article on nail biting, and for the process around dummies, our article on giving up the dummy.
How Is Thumb Sucking Addressed in Therapy?
When families come in about this habit, the first step is to understand what function the habit serves in the child's life. In the parent meeting, when the behaviour began, in which situations it increases, how the family has responded so far and the child's general emotional state are assessed.
With school-age children, habit reversal work based on cognitive behavioural principles can be carried out. In this work, the child learns to notice when the behaviour starts, to recognise the urge that comes before it and to replace it with another behaviour that keeps the hands busy. The success of this work depends largely on the child's willingness and the family's supportive attitude.
With younger children, or when there is a marked anxiety, sibling jealousy or theme of separation behind the habit, play therapy can be a suitable route. As the child expresses their feelings in play and discovers other ways of calming down, their need for their thumb may also decrease. To learn more about this approach, you can visit our child and play therapy page.
Frequently Asked Questions
Which is more harmful: thumb sucking or a dummy?
Both can have similar effects on the teeth when used for long periods and intensively. One advantage for families using a dummy is that they can plan the time to stop themselves; with the thumb, the timing is largely determined by the child's own wish. That is why giving up the thumb can be a longer process for some children.
Should I take my child's thumb out of their mouth while they sleep?
Gently taking the thumb out of the child's mouth once they are in deep sleep is not a problem as long as it doesn't wake them. But there is no need to turn this into a nightly struggle. For school-age children, a night-time reminder chosen with the child's agreement is more useful.
Does thumb sucking cause speech disorders?
Long-term intensive sucking can contribute to difficulty producing some sounds by affecting the position of the teeth and tongue. However, thumb sucking is not the cause of every speech difficulty. If you have a concern about speech, an assessment by a speech and language therapist will guide you.
When is an orthodontic appliance needed?
This decision is made only by a dentist or orthodontist, following an examination of the mouth. Some appliances can be used to make sucking more difficult; however, even when an appliance is used, the child's willingness to stop and the family's supportive attitude remain important.
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Eda Erkan Alapala
Klinik Psikolog. İstanbul Kent Üniversitesi Klinik Psikoloji Tezli Yüksek Lisans mezunu; bilişsel davranışçı terapi, çocuk merkezli oyun terapisi ve çocuk-ergen psikoterapisi alanlarında eğitimlerini tamamlamıştır.
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