Your comprehensive guide to breathing

mouth breathing damages your health

Table of Contents


Breathing is a vital body function that ensures the exchange of oxygen and carbon dioxide between the internal milieu and the external environment. (1)

The main actor in this activity is the respiratory system, which is divided as follows:

- Upper respiratory tract (e.g. nose, throat, larynx)

- Lower respiratory tract (e.g. trachea, bronchi, lungs)

Every single component is prone to certain diseases that can affect the entire respiratory process.

This article examines the physiological mechanism of breathing on the one hand and the damage to the body caused by mouth breathing on the other.

Comprehensive Guide to Breathing

Physiological breathing

Breathing is a result of the pressure differential between the lungs and the atmosphere.
When the pressure in the lungs is less than that of the atmosphere, air flows into the lungs to compensate for this pressure difference. As soon as the pressure differential shifts, air rushes out of the lungs to restore balance.
The following diagram shows the pressure fluctuations during inspiration and expiration.

Physiological breathing

Why is mouth breathing harmful to your health?

Oral breathing is defined as the movement of air in and out of the lungs, using the mouth as the sole outlet. As explained above, normal breathing is through the nose when the air is flowing into the lungs and through the mouth when it is flowing outward.
Mouth breathing means that air flows through the mouth as you inhale and exhale, which can cause various health problems.
Adults who breathe through their mouths are more likely to develop insomnia, chronic fatigue, and reduced productivity. These symptoms were compared to nasally breathing subjects and the results confirmed the presence of an abnormality.

mouth breathing damages your health

Children and mouth breathing

However, these consequences are no comparison to how children can suffer from mouth breathing. Because breathing plays a crucial role in the anatomical modeling of the orofacial structures and airways.

In fact, experts found that children who breathe through their mouths untreated for long periods of time are prone to various medical conditions, including facial deformities that make them look less attractive.

In addition, malocclusions (e.g. skeletal class II or III), long-face syndrome or Gothic palates have been observed in such children.

Over time, these anatomical malformations lead to serious complications such as obstructive sleep apnea, chronic snoring and an increased susceptibility to airway collapse.

One of the main contributors to such abnormalities is the soft palate, which is shaped depending on the type of air flow (e.g., oral air flow, nasal air flow).

In a study by the International Journal of Pediatrics, researchers found that mouth breathing, although labeled a "benign" habit, can cause significant damage to the mental and physical health of children. This is because it results in lower airway restrictions, sleep disorders, reduced cognitive abilities and a lower quality of life. (3)

Mouth breathing means stress

Despite the miraculous properties of our brain, it is subject to several factors that can trigger a generalized stress response through the chronic release of important hormones.

As a result, the sympathetic nervous system is activated to induce a “fight or flight response” in the patient. (4)

Measuring stress hormones in the blood leads to abnormal levels of adrenaline, noradrenaline, and cortisol. (5)

In simpler terms, mouth breathing puts you in a sustained, physiological state of stress, similar to how your body reacts to a bear chase.

In the next few sections, we'll look at the damage that stress caused by mouth breathing can cause.

What are the common effects of stress induced by mouth breathing?

The chronic increase in stress hormones causes havoc in most organ systems by disrupting their physiological and metabolic activities.

Here are some of the effects mouth breathing can be responsible for:


Since breathing through the mouth leads to an increase in the cortisol level, various metabolic pathways are subject to the induced changes.

The two main effects include proteolysis (protein breakdown) and lipogenesis (fat storage), which can do more damage than meets the eye by increasing both weight and blood sugar and pressure. (6)

The breakdown of protein breaks down the collagen fibers, causing the classic striae distensae (ie, stretch marks).

Breathing through the mouth can also influence the patient's appetite and, among other things, induce so-called binge eating in order to distract him from his stress and anxiety. (7)

In summary, chronic stress caused by mouth breathing can lead to significant weight gain, which also makes the patient susceptible to a variety of unpleasant diseases.

However, the opposite effect can occur in a subgroup of patients, including anorexia and weight loss.

Increased risk of diabetes mellitus

Type 2 diabetes is the number one endocrinological disease worldwide.

Every year, millions of patients die from the complications of this disease due to uncontrolled blood sugar levels.

Despite the millions that are invested annually, it is still up to the scientists to determine the exact causes of this ailment.

The attempt to identify the risk factors was ultimately successful and led to the following results:
  • Obesity
  • Permanent sitting
  • high blood pressure
  • Diabetes in the family
  • Chronic stress - whatever the cause

Obviously, regardless of the trigger, chronic stress can be a major risk factor for type 2 diabetes. (8th)

Cardiovascular diseases

"Cardiovascular disease" is an umbrella term for various diseases that are collectively responsible for the majority of deaths worldwide.

These diseases weaken the body and have risk factors similar to those of diabetes mellitus. The main cause of the underlying processes is the chronic increase in adrenergic hormones and cortisol. They encourage the narrowing of the blood vessels and force the heart to pump the blood against higher pressures.

In addition, obesity and dyslipidemia - high LDL, low HDL - are often caused by stress, which makes the situation worse. (9)

Comparison of nasal and mouth breathing

It is estimated that a third of the population does not breathe through their nose. The cells, tissues and organs are not given an adequate supply of oxygen.

In trying to analyze this problem, Dr. Chandra Patel that the breathing mechanism has been on autopilot all our lives. This may lead some people to believe that their breathing is working optimally.

Also, the core problem that makes people switch from nasal to mouth breathing is complete automation.

In addition to mouth breathing, upper chest breathing, sighing, and noticeable breathing are also abnormalities with dire consequences.

Despite the automation of breathing, the value of the lungs should not be underestimated, which is particularly evident when the upper / lower airways are diseased and breathing becomes an extremely difficult task.

According to the ENT doctor Dr. Pat Barelli, the role of the nose in our general health and breathing has been neglected by doctors.

In short, the nose was originally designed to control breathing and smell, while the mouth was responsible for eating, drinking and entertaining.

The most common complications of mouth breathing

Unfortunately, 40% of adults are reported to use their mouths to breathe, especially in the early hours of the morning.

Nose vs Mounth
Mouth breathing is more common in people with a blocked or restricted nasal passage. (10)

For example, a crooked septum or small nostrils can be the reason for switching from nasal to mouth breathing.

While these patients share an underlying mechanism that causes them to breathe through their mouths, the vast majority of those affected are unintentionally prone to this bad habit.

As mentioned earlier, several studies have demonstrated the undesirable effects of chronic mouth breathing and the effects on various organ systems.

According to Jefferson (2010), the vast majority of doctors lack knowledge of the relationship between mouth breathing and facial growth. (11)

For example, breathing through the mouth contributes to the development of "tongue pressure" that affects speaking, swallowing, and chewing.

Tongue pressing occurs when the tip of the tongue rests against or between the front teeth and the tongue lies deeper in the oral cavity. Normally, the tongue should rest in the upper part of the mouth (with the mouth closed) and support the upper jaw from the inside.

In addition, mouth breathing is involved in exercise-induced asthma. In a study published by the American Review of Respiratory Disease, asthma patients did not experience exacerbations after physical exertion when breathing through their nose. Breathing through the mouth, however, resulted in a narrowing of the bronchi and the classic signs and symptoms of an asthma attack. (12)

Mouth breathing can also cause dry mouth, which increases the risk of bacterial and viral infections in the oral cavity.

It is clear that breathing through the mouth can lead to a myriad of preventable complications. Therefore, one should concentrate more on inhaling so that nasal breathing becomes second nature.

Nasal breathing - important for health

Oxygen supply

Nasal breathing is better for the body than mouth breathing because it drives oxygen to the lower lungs while the latter stagnates oxygen in the upper lungs.

An important characteristic of the lower lungs is their ability to stimulate the parasympathetic nervous system to induce feelings of calm and mindfulness. This explains why you feel better after taking a deep breath through your nose.

In contrast, the upper lobes of the lungs contain sympathetic nerves that promote feelings of fear and distress.

Basically, all lobes of the lungs are stimulated by nasal breathing so that breathing is as efficient as possible.

Removes carbon dioxide

Nasal breathing minimizes the effects of huffing and panting during physical activity by removing CO2 in an efficient manner. This happens when the lower lungs are stimulated by the air flow. Since the lower lungs are supplied with more blood, the exchange of breathing gases runs at full speed to get rid of the carbon dioxide.

Improves the breathing mechanism

When nasal breathing becomes your natural breathing, your body learns the best method of diaphragmatic contraction to optimize the process of breathing gas exchange and energy expenditure.

Reduces the risk of gastroesophageal reflux disease and a diaphragmatic hernia

Nasal breathing helps patients avoid reflux disease and hiatal hernia symptoms due to the dynamic movement of the diaphragm. Because it massages the stomach walls and thus prevents structural pathologies.

Massages the heart and lungs

Nasal breathing provides deep breaths that force the entire chest to move and allow all 12 ribs to massage the heart and lungs.

Improves lymph flow

Nasal breathing and activation of the entire chest promote the healthy flow of lymphatic fluid, as does the drainage of fluids from the lower extremities into the circulation by creating negative pressure in the chest.

Optimizes the musculoskeletal system

Nasal breathing and activation of the entire chest are critical to the flexibility and elasticity of the spine, head, neck and lower back. 

Produces nitric oxide

Nasal breathing has been shown to increase the production of nitric oxide, an important cellular signaling molecule that is involved in several physiological processes, including vasodilation (widening of blood vessels), increasing blood flow, and protecting organs from reactive oxygen species.

The discovery of nitric oxide was awarded the Nobel Prize. It is considered a panacea molecule, but its production during mouth breathing has not been proven.

Controls vital parameters

Nasal breathing lowers blood pressure, heart rate, and breathing rate to create a feeling of calm and peace.

Optimizes brain activity

When it comes to the activity of alpha waves in the brain, nasal breathing is far more effective compared to mouth breathing.

The reason for this finding is that alpha waves are only generated during meditative states and these are mainly observed during nasal breathing.

In addition, nasal breathing increases brain wave coherence.

Improves energy expenditure

According to the Borg Perceived Exertion Scale, nasal breathing causes less fatigue and delayed muscle pain (DOMS) compared to mouth breathing. (13)

Accelerates recovery

Nasal breathing allows for faster recovery and greater resistance compared to mouth breathing. It is also less stressful than the latter. This was proven by the (psycho-) galvanic skin reaction.

Nasal breathing optimizes gas exchange

Contrary to popular belief, carbon dioxide plays an important role and is not just a waste product.

The functions set in motion by CO2 include balancing blood pH, bronchodilation of the airways, and vasodilation of blood vessels.

CO2 also interacts with hemoglobin to displace oxygen.

In a recent study from the University of Warwick, Professor Nick Dale stated that “The exciting implication of our study is that carbon dioxide is much more than just a waste product: it can signal physiological information directly. Our work shows the mechanism by which this occurs via connexin 26 (a protein encoded in humans by the GJB2 gene). "

He added, “Since connexin 26 is found in many tissues and organs such as the brain, skin, inner ear, liver and uterus during pregnancy, this discovery should reassess the potential for carbon dioxide signals usher in many different processes such as controlling blood flow, breathing, hearing, procreation, and childbirth.

In addition, the human body requires about 5% of the carbon dioxide in the alveoli compared to the 0.03% that is present in the atmosphere. (14)

As a result, the body must produce and store CO2 in the blood and lung parenchyma in order to maintain gas balance.

About 95% of oxygen are transported in the blood and bound to the hemoglobin. The oxygen content of the arterial blood (CaO2) is therefore determined by the arterial oxygen saturation of the hemoglobin (SaO2) and the hemoglobin concentration (Hb).
CO2 in the blood
In addition, when the capillary PCO2 (carbon dioxide partial pressure) rises, the Bohr effect occurs (15) and results in an excessive amount of oxygen in the cell tissue. However, when the opposite is the case, the bond between oxygen and hemoglobin is strengthened, so that less oxygen is released into the tissues and organs.

Excessive breathing is typical of mouth breathing. In doing so, large amounts of carbon dioxide are distributed in the atmosphere, which shifts the curve to the left. The result is hypoxemia of the tissue.

Nasal respiration has the opposite effect by allowing gas exchange under optimal conditions with a relatively stable affinity between hemoglobin, oxygen and carbon dioxide.

Nitric oxide and nasal breathing

Nitric oxide is a gas that was long considered an environmental pollutant until, in 1998, three American scientists discovered that it played an important role in the cardiovascular system. (16)

The scientists originally named this gas "Endothelium-Derived Relaxing Factor" (EDRF) when they discovered that it is continuously produced by the endothelium. The name was later changed to nitric oxide, which is in use today.

The enzymes responsible for producing nitric oxide are found in the nose and sinuses. In addition, nitric oxide is known to be a powerful bronchodilator and vasodilator. (17)

It helps lower blood pressure and increase the oxygen absorption capacity of the lungs. It also has strong antibacterial, antiviral, and antifungal properties. (18)

Lundberg stated (18): "Nitric oxide gas from the nose and paranasal sinuses is inhaled with each breath and enters the lungs in a diluted form to improve pulmonary oxygen uptake by local vasodilation. In this sense, nitric oxide can be considered an 'aerocrine' hormone produced in the nose and paranasal sinuses and transported to a distant site of action with each breath."

In addition, it has been referred to as a "powerful molecule" by Chang (2011) for its beneficial performance as Dr. Chang found that nitric oxide plays a crucial role in the human body, particularly in the cardiovascular, neuroendocrine, and immune systems. (19)

How nitric oxide can prevent heart disease and strokes

As mentioned above, oral breathing is the cause of various complications that thanks to nasal breathing can be avoided.

To facilitate this change, so-called "breathing training" is carried out in which unhealthy habits are replaced by physiological breathing.

Famous methods of breathing training include the Buteyko Method, Papworth Method, and Pranayama (this is the regulation of the breath used through yoga techniques and exercises). (20)

Closing word

Mouth breathing leads to a variety of complications that can affect your own mental and physical health and that of your child.

By switching to nasal breathing, you not only prevent many diseases, but also benefit from the advantages mentioned above, as well as from those that are currently being scientifically researched.

Hopefully this article has helped you understand both the benefits of breaking bad habits and the benefits of nasal breathing.

If you have any questions about the types of breathing explained, feel free to ask them in the comments below.


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2-Respiratory Physiology. (1996). The Journal of Physiology, 497 (P), 21P-31P.

3-Trabalon, M., & Schaal, B. (2012). It takes a mouth to eat and a nose to breathe: abnormal oral respiration affects neonates' oral competence and systemic adaptation. International journal of pediatrics, 2012.

4-LeBouef, T., & Whited, L. (2019). Physiology, Autonomic Nervous System.

5-Ranabir, S., & Reetu, K. (2011). Stress and hormones. Indian journal of endocrinology and metabolism, 15 (1), 18.

6-Sinha, R., & Jastreboff, AM (2013). Stress as a common risk factor for obesity and addiction. Biological psychiatry, 73 (9), 827-835.

7-Yau, YH, & Potenza, MN (2013). Stress and eating behaviors. Minerva endocrinologica, 38 (3), 255.

8-Surwit, RS, Schneider, MS, & Feinglos, MN (1992). Stress and diabetes mellitus. Diabetes care, 15 (10), 1413-1422.

9-Assadi, SN (2017). What are the effects of psychological stress and physical work on blood lipid profiles ?. Medicine, 96 (18).

10-Stewart, M., Ferguson, BJ, & Fromer, L. (2010). Epidemiology and burden of nasal congestion. International journal of general medicine, 3, 37.

11 Jefferson, Y. (2010). Mouth breathing: adverse effects on facial growth, health, academics, and behavior. Gen Dent, 58 (1), 18-25.

12- (2000) Guidelines for Methacholine and Exercise Challenge Testing-1999. American Journal of Respiratory and Critical Care Medicine 161: 1, 309-329. Online publication date: 14-Dec-2012.

13- Borg, G. (1998). Borg's perceived exertion and pain scales. Human kinetics.

14- Schaefer, KE, Hastings, BJ, Carey, CR, & Nichols Jr, G. (1963). Respiratory acclimatization to carbon dioxide. Journal of applied physiology, 18 (6), 1071-1078.

15- Jensen, FB (2004). Red blood cell pH, the Bohr effect, and other oxygenation-linked phenomena in blood O2 and CO2 transport. Acta Physiologica Scandinavica, 182 (3), 215-227.

16- Marsh, N., & Marsh, A. (2000). A short history of nitroglycerine and nitric oxide in pharmacology and physiology. Clinical and Experimental Pharmacology and Physiology, 27 (4), 313-319.

17- Moncada, S., & Higgs, EA (1991). Endogenous nitric oxide: physiology, pathology and clinical relevance. European journal of clinical investigation, 21 (4), 361-374.

18- Moncada, S., & Higgs, EA (1991). Endogenous nitric oxide: physiology, pathology and clinical relevance. European journal of clinical investigation, 21 (4), 361-374.

18- Lundberg, JO, Weitzberg, E., & Gladwin, MT (2008). The nitrate – nitrite – nitric oxide pathway in physiology and therapeutics. Nature reviews Drug discovery, 7 (2), 156-167.

19- Chon, K., Chang, JS, Lee, E., Lee, J., Ryu, J., & Cho, J. (2011). Abundance of denitrifying genes coding for nitrate (narG), nitrite (nirS), and nitrous oxide (nosZ) reductases in estuarine versus wastewater effluent-fed constructed wetlands. Ecological Engineering, 37 (1), 64-69.

20 Courtney, R. (2008). Strengths, weaknesses, and possibilities of the Buteyko breathing method. Biofeedback, 36 (2), 59-63.

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