Does your child often have their mouth open, sleep with their lips apart or snore regularly? Occasional mouth breathing, for example during a cold with a blocked nose, does not have to mean there is a problem. If this way of breathing continues when your child is well, however, it is worth taking a closer look.
Nasal breathing is the natural way of breathing at rest. The nose cleans, warms and humidifies the air we breathe in. When airflow through the nose is obstructed, a child may start to breathe through the mouth more often.
If this breathing pattern persists for a long time, it may occur alongside changes in the function of the muscles of the mouth, tongue position, the way of swallowing, articulation, and the development of the bite and of the craniofacial structures. This does not mean, however, that mouth breathing on its own automatically leads to a particular malocclusion. A child’s development is influenced by many factors, which is why the most important thing is to establish the cause of the problem.
Why does a child breathe through the mouth?
Mouth breathing is often the consequence of difficulty breathing through the nose, rather than simply an unwanted habit.
Possible causes include:
- enlarged adenoids (the pharyngeal tonsil), commonly known as the “third tonsil”,
- enlarged palatine tonsils,
- allergic rhinitis,
- chronic rhinitis,
- recurrent infections and the nasal blockage that comes with them,
- certain anatomical abnormalities that obstruct airflow through the nose.
If a child has difficulty breathing through the nose for a long time, they may gradually get used to breathing through the mouth. Even once the original cause has resolved, the normal breathing pattern does not always return straight away.
It is therefore worth distinguishing between two situations: a child who cannot breathe freely through the nose, and a child whose cause of obstruction has been resolved but whose abnormal breathing pattern persists.
What can chronic mouth breathing mean?
During a speech and language assessment, we look at, among other things, the way of breathing, the position of the lips and tongue at rest, the way of swallowing and the function of the muscles in and around the mouth.
In a child who has breathed through the mouth for a long time, the following may be observed, among other things:
- the mouth frequently stays open,
- a low tongue position at rest,
- difficulty keeping the tongue and lips in the correct position,
- an abnormal swallowing pattern,
- reduced function or abnormal action of certain orofacial muscles,
- difficulty producing some speech sounds.
Not every child will show all of these signs. Their presence needs to be assessed individually, because similar difficulties can have different causes.
Mouth breathing, craniofacial development and the bite
Chronic mouth breathing is the subject of numerous studies on the development of the upper and lower jaw and the bite. Systematic reviews point to an association between mouth breathing and certain features of craniofacial development, as well as a higher prevalence of certain malocclusions. At the same time, the available studies have their limitations and do not allow us to conclude that mouth breathing is the sole cause of each of these changes.
So rather than focusing only on how the bite looks or where the tongue sits, the most important question to answer is: why is your child not breathing freely through the nose?
Mouth breathing during sleep
It is worth observing your child at night too. Mouth breathing can occur as part of sleep-disordered breathing, including obstructive sleep apnoea.
Pay particular attention to:
- regular or loud snoring,
- mouth breathing during sleep,
- restless sleep,
- frequent waking,
- observed pauses in breathing,
- unusual sleeping positions,
- excessive sweating at night,
- difficulty concentrating or behavioural difficulties during the day,
- marked tiredness despite sleeping for long enough.
If there are pauses in breathing or marked difficulty breathing during sleep, your child should be seen by a doctor.
Can mouth breathing affect oral health?
Yes. When a child breathes through the mouth, the mouth can be more prone to drying out. Saliva has many protective functions, so chronic dry mouth can matter for oral health and may increase the risk of certain dental problems.
If the problem persists, it is therefore worth remembering not only a consultation about breathing, but also regular dental check-ups.
What should you do if your child breathes through the mouth?
The most important thing is to establish the cause, rather than simply correcting appearances.
If your child has a blocked nose, simply encouraging them to close their mouth will not solve the problem. First, you need to check whether there is an obstruction preventing normal nasal breathing.
Depending on the symptoms, consultations with different specialists may be helpful.
ENT specialist – can assess, among other things, how clear the nose is, as well as the adenoids and palatine tonsils, and decide whether further treatment is needed.
Allergist – a consultation may be advisable if the symptoms suggest allergic rhinitis or another allergic condition.
Dentist or orthodontist – can assess oral health, the bite and the development of the maxillofacial structures.
Speech and language therapist or neurologopedist – as part of the assessment, they can evaluate, among other things, the way of breathing, the resting position of the tongue and lips, the way of swallowing and the function of the articulators.
Where necessary, speech and language therapy can be part of a broader approach carried out together with other specialists.
Can a speech and language therapist help with mouth breathing?
Yes, but speech and language therapy does not replace treatment of a medical cause.
If your child cannot breathe freely through the nose because of chronic obstruction, allergy or enlarged tonsils, the cause needs to be addressed first.
If the airway is clear and abnormal functional patterns nevertheless persist, a speech and language therapist can work on, among other things:
- the correct resting position of the tongue,
- lip posture,
- the way of swallowing,
- the function of the orofacial muscles,
- a correct breathing pattern at rest,
- consolidating correct functional patterns.
The scope of therapy should always be adapted to the child’s age, abilities and the cause of the difficulties.
Summary
Mouth breathing in a child does not always mean there is a problem, especially if it appears temporarily during an infection. If it persists for a longer time, however, including outside periods of illness, it is worth finding out what is behind it.
An early assessment makes it possible to find the likely cause and to decide in good time whether the child needs further investigation or therapy.
Sources and further reading: Zhao Z. et al., Effects of mouth breathing on facial skeletal development in children: a systematic review and meta-analysis, BMC Oral Health, 2021; Grande E.S. et al., Mouth Breathing and Craniofacial Development in Children: A Systematic Narrative Review and Clinical Implications, Healthcare, 2026; Association between mouth breathing and pediatric obstructive sleep apnea: a systematic review, 2025. The content of this article is for information only and does not replace an individual assessment or medical consultation.