Mouth Breathing in Children

You’ve seen it. Your child sleeps with their mouth open. They snore. Their lips are always dry. Maybe they breathe through their mouth during the day too. You’ve asked about it, but everyone keeps telling you it’s nothing. Just a phase. Allergies. They’ll grow out of it.

That’s what I was told. Over and over.

But it didn’t sit right with me. My gut kept saying something was off. And I was right. What looked like “just mouth breathing” turned out to be a problem with how my son’s face and airway were developing. We share our whole story here. 

I’m sharing this because if you’re here, you’re probably seeing the same things in your child. This post will show you the seven signs I wish I’d known earlier. You’ll see how mouth breathing is tied to jaw growth, what to watch for during sleep versus the day, and how you can take action early — before it becomes a much bigger issue.

Let’s get into it.

Why Mouth Breathing Matters

A lot of parents are told not to worry when their child breathes through their mouth. It’s often brushed off as a temporary habit or blamed on allergies or congestion. But when mouth breathing becomes the default, especially during sleep or quiet moments, it can begin to affect how the face, jaw, and airway develop.

Nasal breathing supports healthy growth. When a child breathes through their nose, their tongue rests against the roof of the mouth, helping to widen the upper jaw and create space for both the teeth and the airway. The lips stay closed, facial muscles stay balanced, and the lower jaw grows forward in line with the rest of the face.

Mouth breathing changes that process. The tongue sits low, the lips stay open, and the muscles around the cheeks and jaw lose the support they need. Over time, this leads to a narrower upper jaw, a high palate, and a lower jaw that often shifts backward. As the face grows longer and more compressed, the airway also becomes more restricted.

When the jaw doesn’t grow properly, there’s often not enough room in the mouth or behind the nose for smooth airflow. This can lead to snoring, disrupted sleep, frequent waking, or even short pauses in breathing at night. These issues affect more than rest—they can influence behaviour, focus, and overall energy during the day.

Nasal breathing plays a key role in how the body functions. It filters and humidifies the air, supports oxygen uptake, and helps regulate immune function. It also reinforces the correct posture of the tongue and jaw, guiding proper growth. None of this happens with mouth breathing.

If your child often breathes through their mouth while awake or asleep, it’s worth looking into. Even if it starts with congestion or a structural issue like enlarged tonsils, the longer it continues, the more it shapes how your child grows and how well they breathe.

How Mouth Breathing Affects Facial Development

During childhood, the bones of the face are still forming, and the way a child breathes plays a key role in how those bones grow. Proper development depends on the tongue sitting at the roof of the mouth and the lips staying closed. This creates outward pressure on the upper jaw, keeping the palate flat and encouraging the face to grow forward in balance.

When a child habitually breathes through their mouth, the tongue sits low instead of supporting the upper jaw. Without that pressure, the jaw stays narrow and the palate becomes high and arched. At the same time, the lower jaw often drops and shifts backward. These changes lead to what’s known as vertical growth — the face becomes longer and narrower over time, and the balance between the upper and lower jaws is disrupted.

This can result in crowded teeth, a poor bite, or a recessed chin. It also changes the appearance of the face in ways that are often overlooked. You might see a gummy smile, lips that don’t close easily, a mouth that stays open at rest, or dark circles under the eyes. These are signs that the muscles and bones of the face aren’t working together as they should.

The changes are not just cosmetic. A narrow upper jaw creates less space in the mouth, which leaves less room for the tongue to sit comfortably. When there isn’t enough room for the tongue, it tends to fall backward into the throat, especially during sleep. This can make breathing more difficult and increase the risk of sleep disruptions.

The growth of the face, teeth, and airway are all connected. When mouth breathing becomes the norm, it can throw off that growth pattern and create issues that affect more than just the appearance of the smile. It can influence sleep quality, behaviour, and how a child feels day to day.

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7 Warning Signs You Shouldn’t Ignore

Each of these signs can show that something is interfering with your child’s breathing, jaw growth, or facial development. On their own, they might seem minor. Together, they often point to an underlying issue that needs attention.

1. Mouth open at rest

When a child is relaxed, their mouth should be closed and their tongue should rest against the roof of the mouth. If you regularly see your child with their lips apart while sitting still or watching something, it may be a sign that their muscles aren’t supporting proper mouth posture. This can affect how their jaw and airway develop over time.

2. Snoring or noisy breathing during sleep

Children should breathe quietly through their nose when they sleep. Any snoring, heavy breathing, or gasping can suggest that their airway is being blocked. This is often caused by enlarged tonsils, a narrow palate, or a small lower jaw. These blockages can reduce airflow and interfere with healthy sleep.

3. Dry lips or bad breath

If your child wakes up with dry lips, a dry mouth, or bad breath, they’re likely breathing through their mouth overnight. Nasal breathing keeps the mouth closed and moist. When the mouth stays open during sleep, it dries out the tissues and can increase the risk of cavities, gum irritation, and poor oral hygiene.

4. Crowded teeth or a narrow smile

The position of the tongue during childhood helps shape the upper jaw. If the tongue isn’t pressing against the roof of the mouth, the jaw can stay too narrow and won’t create enough space for incoming teeth. As a result, teeth may come in crooked or overlap. This is often one of the first visible signs of poor oral posture.

5. Long face or weak chin

Children who mouth breathe over long periods often develop facial features that grow downward instead of forward. This type of growth leads to a longer, narrower face and a lower jaw that appears small or set back. These changes reduce space in the airway and can make breathing less efficient, especially at night.

6. Daytime tiredness or hyperactivity

Poor breathing during sleep leads to poor quality sleep. Some children respond with fatigue and low energy, while others seem constantly active or easily distracted. If your child struggles with focus, irritability, or emotional regulation, it’s worth considering whether sleep or breathing might be part of the cause.

7. Difficulty closing lips or chewing with the mouth closed

When the muscles around the mouth aren’t strong enough to keep the lips sealed, or if the jaw is misaligned, children often chew with their mouth open or struggle to close their lips at rest. These signs can point to muscle imbalance or a structural issue affecting the way their face is growing.

Daytime vs Night-time Mouth Breathing

Mouth breathing during the day and mouth breathing during sleep are both important to pay attention to, but they can mean slightly different things — and together, they often point to a bigger issue.

Daytime Mouth Breathing

When a child breathes through their mouth while awake, it’s often linked to muscle imbalance or poor oral posture. In these cases, the lips may not stay closed, the tongue rests low in the mouth, and the child might not even realise their mouth is open. This can become a habit that continues even when there’s no congestion or physical blockage.

Daytime mouth breathing also affects how the face develops. The muscles around the lips and cheeks aren’t engaged properly, and the tongue isn’t helping the upper jaw grow wide and strong. Over time, this can lead to changes in jaw shape, facial length, and bite alignment.

It can also affect how the child eats and speaks. Children who breathe through their mouths may chew with their mouths open, swallow improperly, or have speech that sounds unclear or nasal. These signs all point to underlying dysfunction in how the muscles of the mouth and face are working together.

Night-time Mouth Breathing

Mouth breathing at night is usually more concerning. During sleep, the body should be fully relaxed, with the mouth closed and the nose handling all airflow. If a child can’t keep their mouth closed at night, it often means the airway is being blocked — either by enlarged tonsils, a narrow palate, or a jaw that’s too small to hold the tongue forward.

Night-time mouth breathing is often linked to signs of sleep-disordered breathing. These include:

• Snoring or noisy breathing

• Tossing and turning

• Night sweats

• Teeth grinding

• Bedwetting

• Sleeping with the head tilted back or the mouth wide open

These symptoms suggest that the airway isn’t open enough, and the child is compensating to get enough air. This disrupts deep sleep and reduces oxygen intake, which can affect behaviour, learning, mood, and physical growth.

The Connection Between Day and Night

In many cases, daytime and night-time mouth breathing are connected. A child who breathes through their mouth all day is more likely to do the same at night. And if sleep is poor due to airway obstruction, the body may stay in compensation mode even when awake.

Both need to be addressed. Correcting daytime breathing helps improve muscle tone, tongue posture, and jaw development. Treating night-time issues improves sleep quality, brain function, and overall health. If only one side is treated, the problem often comes back or continues to affect development.

What Causes Mouth Breathing in Children

Mouth breathing is always a response to a physical issue. Children aren’t choosing to breathe through their mouths — they’re doing it because something is making nasal breathing difficult or impossible. The longer this goes on, the more it affects how their face and airway grow.

1. Blocked Nose from Allergies or Chronic Congestion

If your child has a stuffy nose most of the time, they’ll start breathing through their mouth to get enough air. This can be caused by:

• Environmental allergies (like dust, pollen, mould, or pet dander)

• Food sensitivities, especially to dairy or gluten

• Ongoing inflammation in the nose or sinuses

Chronic nasal congestion limits airflow through the nose, which forces the body to rely on the mouth instead. This can disrupt proper facial growth and set the stage for long-term issues if left unaddressed.

2. Enlarged Tonsils or Adenoids

Tonsils and adenoids are lymphatic tissues that sit at the back of the throat and nose. In many children, they become enlarged and block the airway, especially when lying down. This makes nasal breathing harder and mouth breathing more likely — particularly during sleep.

You might notice:

• Snoring or noisy breathing at night

• Gasping or waking during sleep

• Trouble swallowing or chewing

• Frequent ear infections

When tonsils and adenoids are too large, they reduce space in the airway and disrupt normal breathing patterns, especially during critical years of facial development.

3. Underdeveloped Jaws or a Narrow Palate

The position of the tongue is what helps shape the upper jaw. When the tongue doesn’t rest against the roof of the mouth, the jaw doesn’t grow wide enough. This leads to a narrow palate and less room for both the tongue and the nasal airway.

Signs of an underdeveloped jaw or narrow palate include:

• A narrow smile

• Crowded or overlapping teeth

• A small or recessed lower jaw

• Frequent mouth breathing, even at rest

These structural limitations reduce the amount of space available for breathing through the nose and are one of the most common root causes of chronic mouth breathing.

4. Low Tongue Posture and Poor Oral Muscle Tone

The tongue should sit at the roof of the mouth when at rest. If it sits low in the mouth, it can’t support proper jaw development. This low posture often goes hand-in-hand with weak muscles in the lips, cheeks, and neck.

Children with low tongue posture may show signs like:

• Chewing with the mouth open

• Speech delays or unclear articulation

• Forward head posture

• Lips that don’t close easily at rest

These issues aren’t behavioural — they’re mechanical. They suggest that the muscles and structures involved in breathing, eating, and speaking aren’t working as they should. And that often comes back to mouth breathing.

Long-Term Effects of Mouth Breathing

When mouth breathing continues through the early years of growth, it doesn’t just affect appearance — it impacts how a child sleeps, functions, and feels. These effects often build slowly, which makes them easy to miss or dismiss until they’ve become more difficult to correct.

Changes in Facial Structure

Mouth breathing affects how the face grows. Instead of developing forward and wide, the upper jaw stays narrow, the lower jaw shifts back, and the face grows longer. This type of growth can lead to a high palate, a smaller airway, and visible changes like a recessed chin or narrow smile. These changes are often seen as cosmetic at first, but they reflect underlying structural problems that affect breathing and jaw function.

Disrupted Sleep and Airway Problems

A child who breathes through their mouth at night is often not sleeping well. Mouth breathing is linked to shallow breathing, snoring, and frequent waking. Some children even develop sleep-disordered breathing or mild sleep apnoea. Poor sleep affects everything from energy levels to memory, learning, and emotional regulation. Over time, it can lead to chronic tiredness and behavioural issues that are sometimes mistaken for ADHD.

Ongoing Behaviour and Focus Issues

Children who don’t get deep, restful sleep often struggle with focus, emotional control, and daytime behaviour. It’s not that they’re intentionally being inattentive or impulsive — they’re tired. When the brain doesn’t get enough oxygen during sleep, it has to work harder to get through the day. That can show up as mood swings, irritability, trouble sitting still, or difficulty keeping up in school.

More Complex Dental and Orthodontic Needs

Without proper tongue posture and jaw growth, there often isn’t enough space in the mouth for permanent teeth to come in correctly. This leads to crowded teeth, a poor bite, or both. Braces can help straighten teeth, but if the root cause — mouth breathing and poor jaw development — isn’t addressed, relapse or ongoing problems are likely.

Broader Health Impacts

Mouth breathing doesn’t support the body’s natural defences. It bypasses the filtration and humidification systems built into the nose, which can weaken the immune response. It also affects how efficiently the body uses oxygen. Over time, this can contribute to lower energy levels, increased inflammation, and difficulty recovering from illness.

What You Can Do About Mouth Breathing

If you’re seeing signs of mouth breathing in your child, there are clear steps you can take. You don’t have to wait until they’re older or hope they’ll grow out of it. The earlier you act, the easier it is to support healthy breathing and growth.

Support Nasal Breathing First

The first goal is to make sure your child can breathe comfortably through their nose. If nasal breathing isn’t possible, there’s likely a physical reason behind it.

Start by checking for signs of congestion or irritation. In many cases, nasal airflow can be improved with simple changes at home:

• Use saline sprays or rinses to clear mucus

• Run a humidifier at night if the air is dry

• Check for potential allergens in the home, such as dust, pet dander, or mould

• Consider food sensitivities, especially to dairy or gluten, which can cause inflammation in some children

Along with clearing the nose, encourage your child to rest with their lips closed and breathe through their nose during the day. It takes repetition and gentle reminders, but this kind of awareness builds better muscle control over time.

Explore Myofunctional Therapy

Myofunctional therapy uses exercises to strengthen the muscles of the mouth, lips, tongue, and face. It helps retrain how the tongue rests, how your child swallows, and how their lips stay sealed.

This type of therapy is especially helpful if your child:

• Chews with their mouth open

• Has trouble swallowing properly

• Shows signs of speech delay or unclear pronunciation

• Can’t keep their mouth closed at rest

These exercises aren’t difficult, but they do require consistency. When done regularly, they support healthier muscle patterns that make nasal breathing easier and more automatic.

Get an Airway-Focused Dental Assessment

This was the turning point in our journey. Most traditional dentists focus only on teeth alignment. An airway-focused dentist looks at the bigger picture — how your child’s jaws are growing, how their tongue rests, and whether their airway has enough space to function properly.

For our family, this led us to the ToothPillow Program. It’s a program designed to guide jaw growth forward, naturally widen the upper palate, and create more space for the tongue and airway. Unlike braces, which work after the problem has developed and don’t resolve the root issue, this approach supports growth while it’s still happening. Once we started, we noticed changes in sleep quality, focus, and energy that we hadn’t seen from anything else.

You can learn more about how it works here.

Why Early Intervention Matters

Mouth breathing is often overlooked in childhood because it doesn’t always seem urgent. But what happens during these early years lays the foundation for how a child’s face, teeth, and airway develop. If a child is mouth breathing consistently while their bones and muscles are still growing, that growth can shift in the wrong direction.

The earlier you step in, the more you can influence how things grow — not just correct problems after they’ve fully developed. Intervening while the face and jaw are still forming gives you a chance to support better breathing, stronger muscle patterns, and proper jaw development before it becomes harder to change.

Early action can improve how your child sleeps, how they feel during the day, and how their face and airway grow. It can also reduce the need for more invasive or costly treatment later, like extractions, braces, or even surgery.

You don’t need to wait for a referral or for the problem to get worse. If you’re seeing the signs, trust your instincts. Small changes now can lead to much better outcomes later.

If You Think Your Child Has Airway Issues, Here’s What You Can Do

Recognizing that something is off with your child’s breathing or sleep can be difficult, especially when the signs are subtle or dismissed as normal. I’ve experienced that uncertainty myself. But hoping a child will outgrow airway problems often leads to delays that make treatment more complex later on.

Addressing the problem early is important. One of the most helpful tools we found was the Toothpillow Program. It supports proper tongue posture, encourages healthy jaw growth, and creates more space in the airway. It’s designed for home use and is different from traditional orthodontics, which usually focus on tooth alignment rather than breathing and development. The goal here is not just straighter teeth, but a better-functioning airway and improved sleep.

If you’re unsure about what’s going on, you can request a free virtual assessment with a Toothpillow-trained airway dentist. This evaluation looks at how your child breathes, how their face and jaw are developing, and whether early intervention might help. It’s a simple step that can provide clarity and help you decide what to do next to support your child’s long-term health.

When you visit www.toothpillow.com you will see a button to see if your child is a candidate for the toothpillow. If you’d like to go diretly to the form, please visit here:

At this point, you’ll just need to take a few photos of your child and submit them for the FREE consultation. It’s simple: six quick photos and a few basic details, and you’re done! Then, you just wait. Depending on your location, it might take a few weeks to get a response, but trust me, it’s worth it.

Once reviewed, you’ll find out if your child is approved. From there, it’s up to you if you want to move forward. Using my Toothpillow coupon code SOSH makes this initial step completely FREE, giving you a chance to get answers and see what’s possible for your child.

• American Academy of Pediatrics: Sleep Apnea in Children

• PubMed: Pediatric Mouth Breathing and Development

• International Association of Orofacial Myology