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Mouth-breathing: Why it’s bad for you

What is Mouth-Breathing?

Mouth-breathing is breathing through the mouth. It often is caused by an obstruction to breathing through the nose. Chronic mouth breathing may be associated with illness. The term “mouth-breather” has unfairly developed a pejorative slang meaning. Breathing through your mouth directs everything you breathe into your lungs, whilst with nose-breathing, the nasal passages humidify the air you inhale. Breathing through the nose is the proper way to breathe because it warms up the nasal passages and moistens the air you take in. Your mouth doesn’t typically do this, which explains why some mouth-breathers wake up with a dry mouth, sore throat, or both.

Mouth-breathing may have many causes – such as chronic colds, sinus polyps, and allergies.

Picture Credit:Snoring in the sunshine.” by Neil. Moralee is marked with CC BY-NC-ND 2.0.

In the early 20th century, “mouth-breather” was a technical term used by doctors to describe children who were breathing through their mouths due to an underlying medical condition. Some people breathe through their mouths almost exclusively, while other people have a medical condition, such as sleep apnea, where they mainly breathe through their mouths during the night.

Occasional mouth-breathing due to a temporary illness, such as a cold, is no cause for concern, but chronic mouth breathing can signal that a person needs medical intervention or retraining on breathing more easily through their nose.

Four things of importance to note are:

  • Normal breathing is regarded as breathing through the nose with the abdomen gently expanding and contracting with each inhalation and exhalation. No effort is required with breathing being silent and consistent.
  • Mouth-breathing is often quicker than normal, audible, with sighing and visible movements of the upper chest in evidence.
  • Children from as young as six years old (when they start to lose their baby teeth) are at an optimum age to tackle any issues preventing normal nasal breathing and early signs of dental malocclusion (bad bite)[1]. In children, mouth breathing can cause crooked teeth, facial deformities, or poor growth.
  • In adults, chronic mouth breathing can cause bad breath and gum disease. It can also worsen symptoms of other illnesses.

Normal Vs Abnormal Breathing
“During normal breathing, the abdomen gently expands and contracts with each inhalation and exhalation. There is no effort involved; the breath is silent, regular, and most importantly, through the nose. Abnormal breathing or mouth breathing; is often faster than normal, audible, punctuated by sighs, and involves visible movements of the upper chest. This type of breathing is normally only seen when a person is under stress, but for those who habitually breathe through their mouths, the negative side effects of stress and over-breathing become chronic. Habitual mouth breathing has serious implications on an individual’s lifelong health, including the development of their facial structure.”[2]

Physiotherapy can help to cope with abnormal breathing functionality by:

  • Increasing awareness and education about abnormal breathing patterns
  • Reassurance that things can improve
  • Learning how to use nose / mouth breathing in rest
  • Teaching about pacing / mobilising using nasal breathing
  • Control of symptoms during an episode
  • Manual therapy techniques
  • Encourage and support you in staying active or increasing activity levels
  • Breathing retraining in progressively taxing postures
  • Education about proper use for medications where applicable
  • Education about underlying respiratory diagnoses and how they affect your breathing pattern
  • Further recognition of triggers
  • Incorporating relaxation methods into everyday life

Symptoms of abnormal breathing [4],[5]

  • Breathlessness
  • Chest pains
  • Pins and needles
  • Palpitations
  • Undue awareness of your breathing
  • Dizziness
  • Snoring
  • Dry mouth
  • Bad breath (halitosis)
  • Hoarseness
  • Waking up tired and irritable
  • Chronic fatigue
  • Brain fog
  • Dark circles under the eyes

Other medical conditions can cause some of these symptoms, and your Doctor (hopefully) should have excluded these before presuming that a breathing pattern disorder causes them.

Other conditions that can make you feel short of breath include[6]:

  • Lung conditions such as asthma, emphysema, or pneumonia
  • Problems with your trachea or bronchi, which are part of your airway system
  • Allergies
  • Heart disease can make you feel breathless if your heart cannot pump enough blood to supply oxygen to your body
  • Anxiety and panic attacks

If you often have trouble breathing, it is important to find out the cause.

Why nose-breathing is better for you.[7],[8]
The nose produces nitric oxide, which improves your lungs’ ability to absorb oxygen. Nitric oxide increases the ability to transport oxygen throughout your body, including inside your heart. It relaxes vascular smooth muscle and allows blood vessels to dilate. It also stimulates the release of certain hormones, such as insulin.

Nitric oxide is also antifungal, antiviral, antiparasitic, and antibacterial. Put simply, it helps the human immune system to fight infections.

One of the most important reasons for nose-breathing is due to the production of nitric oxide. It exists in the human breath, but little is known about its site of origin or enzyme source. Nitric oxide in normal human breath derives locally from the nose where it can reach high levels during breath-holding. This incredible molecule is said to be produced in mammalian cells by specific enzymes and is believed to play a vital role in many biological events, including blood flow regulation, platelet function, immunity, and neurotransmission. Although nitric oxide is produced in minute amounts, when it is inhaled through the nose into the lungs, it follows the airstream to the lower airways and the lungs where it aids in increasing arterial oxygen tension – enhancing the lungs’ capacity to absorb oxygen.

Conversely, mouth-breathing adults are more likely to experience sleep-disordered breathing, fatigue, decreased productivity and poorer quality of life than those who nose-breathe.

Advantages of nose-breathing over mouth-breathing

  • The nose acts as a filter and retains small particles in the air, including pollen. Mouth-breathing pulls all pollution and germs directly into the lungs and, as a result, chronic mouth breathing may lead to illness.
  • The nose adds moisture to the air being inhaled to prevent dryness in the lungs and bronchial tubes.
  • Nose-breathing warms up cold air to body temperature before it gets to your lungs. Dry cold air in the lungs via mouth-breathing makes the secretions thick, slows the cleaning cilia, and slows down the passage of oxygen into the bloodstream.
  • Nose breathing adds resistance to the air stream, thereby increasing oxygen uptake by maintaining the elasticity of your lungs.

Potential effects of mouth-breathing
Conditions associated with mouth breathing include ADHD, sleep apnea, and snoring. In addition, gingivitis and increased levels of dental plaque are common in persons who chronically breathe through their mouths.

Chronic mouth breathing in children may affect dental and facial growth. It may also lead to the development of a long, narrow face, sometimes termed long face syndrome. Conversely, it has been suggested that a long thin face type, with a corresponding thin nasopharyngeal airway, predisposes to nasal obstruction and mouth breathing.

Diagnosis and Treatment[9]
To diagnose mouth-breathing, your Doctor will:

  • Do visual tests. They’ll look at how well your lips seal, whether you have posture changes, dark eye circles, a long face, an open bite, a high narrow palate, or gingivitis (inflammation of the gum).
  • Do breathing tests. Your Doctor will perform at least two out of the three tests: a graded mirror test, a water retention test, or a lip seal test.
  • Ask questions. They’ll also ask questions like: “Do you keep your mouth open when you are distracted?” or “Do you wake up with a headache?”

Your answers will help them find the cause of your condition and the best way to treat it.

Nasal obstruction (the partial or complete blockage of your nasal airways) is a common reason for mouth-breathing. You may have a blocked nose from common things such as enlarged adenoids (the patches of tissue in the back of your throat and above your tonsils), or you may have nasal allergies.

Mouth-breathing can be reversed through a series of targeted exercises involving the tongue and lips. Stretching and retraining the upper lip is crucial in mastering nasal breathing, as well as retraining the tongue to rest in the roof of the mouth.  Myofunctional Therapy can help the reversal process, as can breath retraining through the Buteyko Breathing Method. See also physiotherapy on page 2 of this paper.

The importance of staying active
The symptoms associated with dysfunctional breathing can be debilitating both physically and emotionally. Symptoms such as breathlessness, fatigue and anxiety can lead to inactivity and isolation. This can lead to a cycle of inactivity.

Being active can help you to:

  • Breathe more efficiently
  • Improve your fitness levels and your tolerance to exercise
  • Improve your mood and emotional well-being
  • Improve your overall quality of life

[Cropped] Image 23 from the 1903 book by William F. Barry, M.D., The Hygiene of the Schoolroom. Barry describes this child as having “the typical face of a mouth-breather.”
Attribution: Internet Archive Book Images, No restrictions, via Wikimedia Commons.
File URL:

Sources and Further Reading

The big snore
Picture Credit:The big snore” by ThePatronSaint is marked with CC BY-NC-ND 2.0.

Caution: Nothing in this paper should be construed or is intended as advice. No articles published by us, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician/medical practitioner.

  1. Source:
  2. Source: an article exploring the benefits of nasal breathing over mouth breathing, with a self-help exercise to help decongest the nose, published at:
  3. Source: See also
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