Some might be surprised to learn that while we humans can breathe through our noses, our mouths, or a combination of the two, we function best when we take in oxygen through our noses.
Nasal breathing keeps us healthy in many ways. For one, the hair that lines our noses and nasal passages is the first line of defense against such potential pathogens as viruses, dirt, bacteria, fungus, or spores. Second, our noses warm and humidify the air we take in, which is better for our overall respiratory health, especially for those who live in a cold climate. And finally, our noses produce nitric oxide, which is an important compound that helps give our cardiovascular and immune systems a boost. Nasal breathing transports the nitric oxide in our nasal passages to our lungs and eventually our bloodstream.
So, if nasal breathing is so good for us, does that mean mouth breathing is bad?
"Mouth breathing itself is not usually a big problem," says Yami Cazoria-Lancaster, D.O., a pediatrician in Yakima, Washington. "It may cause dryness of the lips and bad breath."
She explains that when people are sick with a head cold, most will breathe through their mouths because their nasal passages are swollen and full of mucus. They'll resume taking in air through their nose in a week or two, once the cold has passed.
But chronic mouth breathing that persists for several weeks or months has quite the bad rap and can signal a larger problem that needs to be addressed. If left unresolved in children, mouth breathing has been linked to behavioral problems, facial and dental abnormalities, and even slower growth.
Causes and Symptoms of Mouth Breathing in Children
"A couple of common causes of chronic mouth breathing include allergies and enlarged tonsils," says Dr. Cazoria-Lancaster. She says that children with allergies that make them breathe through their mouth may develop dark circles under their eyes, have persistent nasal congestion, throat clearing, or a cough. Because they won't be sleeping as well, they may be fatigued and have difficulty concentrating in school.
Children with enlarged tonsils and adenoids that are partially blocking their airway may experience similar symptoms.
"They might also not sleep well at night and have snoring or pauses in their sleep [called sleep apnea]," says Dr. Cazoria-Lancaster. "In addition, they may have what we call a 'hot potato voice,' where their voice sounds muffled secondary to the tonsils obstructing the airway."
Jill S. Jeffe, M.D., an assistant professor of pediatric otolaryngology at Rush Medical Center in Chicago, says that when children develop sleep apnea, it is almost always due to large tonsils and adenoids.
"If left untreated, sleep apnea can sometimes lead to behavioral problems such as hyperactivity or difficulty paying attention, and also poor growth," she says. Some researchers attribute slow growth in children with sleep issues to their not producing enough of the growth hormone, which is released during sleep.
Chronic mouth breathing may also lead to dental problems.
"Saliva contains many antimicrobial and anti-inflammatory properties," explains Samuel Low, D.D.S., chief dental officer and vice president of dental and clinical affairs at Biolase. "When mouth breathing occurs, it creates dryness of the mouth. As such, with no protection, the decrease of saliva in the mouth allows for more infection and inflammation." He says that mouth breathing often causes gingivitis, which is characterized by gums that are red or swollen.
While the list of potential health hazards associated with mouth breathing might be alarming to some parents, the good news is that most interventions are fairly straightforward. In the case of enlarged tonsils or adenoids, surgery might be recommended. If a child has allergies, then antihistamines might be prescribed. Sometimes, obesity might be to blame and weight loss will be advised. The main thing is to not ignore it if it doesn't go away.
"If parents are noticing chronic mouth breathing in their children," says Dr. Cazoria-Lancaster, "it should definitely be addressed by their primary care provider."