Breathing is one of the most vital functions of the human body, and provides our bodies with the oxygen we need to survive. But despite this, most of us don’t think about how we breathe.
There are two air passageways to your lungs—your mouth, and your nose—and healthy people use both to breathe. During strenuous exercise, you may breathe through your mouth to help oxygen get to your muscles faster, but consistent mouth breathing (particularly when sleeping) can lead to various health issues.
So what is mouth breathing, what are some of the symptoms, and how is it diagnosed and treated?
What is mouth breathing?
Many health professionals believe we are designed to breathe through our noses from birth. During “normal” breathing, the abdomen gently expands and contracts with each exhalation and inhalation. There is no effort required—breath is regular, silent and most importantly, through the nose. This allows the nasal passages to moisten and warm the air an individual needs to take in.
However, some people breathe in and out mainly through their mouth—known as mouth breathing. It is often audible, faster than normal, punctuated by sighs, and can involve visible movements of the upper chest. Some people breathe through their mouths almost exclusively, while others may have a medical condition (like sleep apnea) where they breathe through their mouths mostly at night.
Occasional mouth breathing can be due to a temporary illness like a cold or other illness that has blocked the nasal passages. In this case, people usually have a runny or stuffy nose as well, and it’s usually not a cause for concern. However, chronic mouth breathing can have serious implications—including the adverse effects of stress—on an individual’s lifelong health. The condition can also become chronic and may be a signal that a person needs medical intervention.
Mouth breathing is typically classified into three types:
- Obstructive—this is often associated with adenoids (the patch of tissue high up in the throat, just behind the nose) or a severely deviated nasal septum (the nasal septum separates the right and left airways of the nasal cavity and divides your two nostrils).
- Habitual—this is a form of over-breathing often caused by an individual’s mouth being much larger than their two nostrils, and it can burden the respiratory system.
- Anatomic—this can involve a deformity in the airway passage and abnormal breathing, which can lead to postural issues and sleep apnea.
What are the benefits of nasal breathing?
Nasal breathing provides various benefits. This is because the nose is equipped with a complex filtering mechanism that purifies the air we breathe before it enters our lungs. During expiration, breathing through our nose helps maintain lung volumes and may indirectly determine our arterial oxygenation. Other advantages include:
- Because our nose acts as a filter, it retains small particles in the air, including pollen.
- Our nose adds moisture to the air to prevent dryness in our bronchial tubes and in our lungs.
- Our nose warms up cold air to our body temperature before it reaches our lungs.
- Nasal breathing adds resistance to the air stream, which increases oxygen uptake by maintaining our lung’s elasticity.
Conversely, mouth breathing slows the cleaning cilia, slows down the passage of oxygen into the bloodstream, pulls germs and pollution directly into the lungs, and allows dry, cold air in the lungs, which can make secretions thicker.
The effect of nitric oxide
One of the most important benefits of nasal breathing is the production of a gas called nitric oxide (NO). NO exists in normal human breath and is derived locally from the nose, where it can reach high levels if we hold our breath. This amazing molecule is believed to be produced in mammalian cells by specific enzymes. NO is also antifungal, antiparasitic, antiviral and antibacterial.
It plays a vital role in many biological events, including platelet function, blood flow, immunity and neurotransmission. It also plays an essential role in maintaining homeostasis and reducing high blood pressure.
Although it is produced in minute amounts, it follows the airstream to our lungs and lower airways when it’s inhaled through our nose. Here it assists with increasing arterial oxygen tension, increases our body’s ability to transport oxygen throughout our body (including inside our heart), and enhances our lungs capacity to absorb oxygen.
What happens in our bodies during mouth breathing?
Even in the absence of oral airflow, mouth breathing, has been shown to increase the propensity for upper airway collapse. The most likely explanation is that jaw opening is associated with a posterior movement of the angle of the jaw, which compromises the oropharynx airway diameter. The oropharynx is the middle part of your throat (pharynx) just beyond your mouth. It also includes your tonsils, the base of your tongue, the sides and walls of your throat and the back part of the roof of your mouth (your soft palate).
This subsequent inferior and posterior movement may shorten the upper airway dilator muscles located between the mandible and the hyoid. The mandible is the largest bone in the human skull, forms the lower jawline and holds your lower teeth in place. The hyoid bone is situated in your neck’s anterior midline between your thyroid cartilage and your chin. This compromise produces unfavourable length-tension relationships in the associated muscles.
What causes mouth breathing?
A range of factors can cause mouth breathing, however, in most cases, it is due to an obstructed (or a partially or completely blocked) nasal airway. Essentially, something is preventing the smooth passage of air into the nose. If this happens, our bodies automatically resort to the other source that provides oxygen — our mouths. Anxiety and stress can also cause people to breathe through their mouth instead of their nose, as it activates the sympathetic nervous system leading to shallow, rapid and abnormal breathing.
What are the symptoms of mouth breathing?
Many people don’t realise they are breathing through their mouth instead of their nose, especially if it happens when they are sleeping. However, some of the symptoms that relate to mouth breathing can include:
- A dry mouth
- Bad breath (halitosis)
- A hoarse voice
- “Brain fog”
- Waking up tired and irritable
- Chronic fatigue
- Sleep disorders like insomnia
- Dark circles under the eyes
- A slightly open-mouthed appearance
- Being a “noisy” eater
What are the symptoms in children?
Like adults, children who are mouth breathers will breathe with their mouth open and often snore at night. But unlike adults, children can often not communicate their symptoms, so it’s important that parents look for the signs. In addition to the above, these include:
- Problems concentrating at school
- Increasing crying episodes at night
- Dry, cracked lips
- A strong mouth odour
What are some of the complications?
Chronic mouth breathing is associated with several health complications, and while an individual will not necessarily experience all of these symptoms and/or complications, they may have one or several of them.
Anyone can develop a habit of mouth breathing due to nasal congestion, but certain conditions increase your risk. These include:
- Hay fever
- Chronic colds
- Chronic allergies
- Chronic or recurring sinus infections
- Chronic stress or anxiety
Other medical issues
However, others will still experience mouth breathing even after the nasal obstruction clears. This can be caused by:
- Enlarged tonsils
- Enlarged adenoids (the glands located in the roof of the mouth)
- A deviated septum (the cartilage in the nose that separates our nostrils)
- Nasal polyps or benign growths of tissue in the lining of the nose
- Enlarged turbinates (the bony shelves in the nose that are covered by glandular tissue)
- The shape of the nose or the size and shape of the jaw
- Postural problems including carrying the head forward to compensate for the restriction of airways. These include neck pain, tension headaches, spinal disc compression tension in the TMJ area and early arthritis.
Speech and dental problems
Mouth breathing can also cause a number of speech and dental problems, including:
- Speech changes, including a greater risk of a speech condition known as a lisp
- Swallowing difficulties
- A greater risk of dental complications, including gum disease, tooth decay, gingivitis and periodontal disease
- Jaw pain, an irregular bite or teeth grinding
- Problems with jaw joints
- Teeth that don’t fit together properly due to an affected bite
People with a history of sleep apnea may find their symptoms are worsened by mouth breathing. This is a potentially serious sleep disorder where an individual’s breathing repeatedly stops and starts during the night, which can lead to snoring and disrupted sleeping patterns. The main types are:
- Obstructive sleep apnea—this is the most common form, which occurs when the throat muscles relax.
- Central sleep apnea—this occurs when an individual’s brain doesn’t send proper signals to the muscles that control breathing.
- Complex sleep apnea syndrome—this occurs when an individual has both of the above.
Are there specific complications in children?
In children, mouth breathing can lead to physical abnormalities and cognitive challenges, and it can also worsen symptoms of other illnesses. Children who aren’t treated for mouth breathing can develop:
- Narrow mouths
- Gummy smiles
- Longer jaws and longer lower faces (often called Long Face Syndrome)
- Faces and jaws that aren’t positioned evenly
- Poor posture
- Large tonsils
- Crooked teeth
- Facial deformities
- Dental malocclusion, including crowded teeth, an overbite or retrognathism
Additionally, children who are mouth breathers often don’t sleep well at night. Poor sleep can lead to:
- Slower than normal growth rate
- Poor academic performance
- Reduced cognitive function
- Inability to concentrate
- Sleep disorders
It’s also worth noting that the negative impacts of airway obstruction via mouth breathing in children can often be confused with hyperactivity, Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD. This is because while adults usually become sluggish when they are tired, children tend to overcompensate. It can lead to moodiness and aggressive and/or emotionally explosive behaviour.
How is mouth breathing diagnosed?
There is no single discernible test to identify mouth breathing — it typically involves a multi-disciplinary approach to minimise the cascading effects of the condition. However, a GP (or geriatrician) might diagnose mouth breathing during a physical examination by looking at the nostrils or by examining the causes of persistent nasal congestion. They may also ask questions about snoring, sleep, difficulty breathing or sinus problems. A dentist may also diagnose mouth breathing during a routine dental examination if you have frequent cavities, bad breath, or gum disease.
How is mouth breathing treated?
Treatments and how to stop mouth breathing depend on the cause and vary from allergies and nasal and respiratory issues to sleep apnea and speech and dental problems.
Nasal congestion, allergies and respiratory infections
If an individual’s nose is frequently congested due to respiratory infections or allergies, treatments include:
- Nasal decongestants, antihistamines and saline or steroid nasal mists and sprays.
- Nasal devices that allow increased airflow through the nasal passages.
- Sleeping on your back with your head elevated to open up the airways and promote nasal breathing.
- Keeping your home clean and free of allergens.
- Installing air filters in your air conditioning systems to prevent the spread of allergens.
- Consciously practising nose breathing during the day.
- Yoga or meditation practice to reduce stress or anxiety.
Ear, nose and throat issues
If a doctor or dentist notices nasal polyps, swollen tonsils and other conditions, they may refer you or your child to a specialist such as an ENT (ear, nose and throat) doctor, myofunctional therapist and/or speech pathologist.
With children, a dentist might recommend your child wears an appliance designed to widen the palate and help open the nasal passages and sinuses. Braces, the surgical removal of swollen adenoids and tonsils and other orthodontic treatments might also help treat the underlying causes.
If obstructive sleep apnea has been diagnosed, Continuous Positive Air Pressure Therapy (CPAP) will be recommended. This involves wearing a CPAP face mask appliance that delivers air to your mouth and nose. The pressure of the air keeps airways from collapsing and becoming blocked.
- 2021, Mouth Breathing: Symptoms, Complications and Treatments, Healthline
- P. McKeown & M, Macalus, 2017, Mouth Breathing: Physical, Mental and Emotional Consequences, Oral Health Group
- 2021, What’s wrong with breathing through the mouth? Medical News Today
- 2021, Sleep apnea, Mayo Clinic
- 2021, Mouth breathing, Wikipedia