What Happens to Your Body When You Breathe Out Through Your Nose or Breathe Out Through Your Mouth

Breathing is something we do without thinking, but it's a powerful tool that, when wielded correctly, can help with everything from stress to core strength to digestion.

With that in mind, we were curious if the way we exhale—nose vs. mouth breathing—makes a difference in general and while exercising. Long story short: It absolutely does.

Keep reading to learn all about the intricacies of mouth breathing vs. nose breathing—and to find out which is better and why.

Nose breathing benefits

"The nose possesses over 30 functions," says Ally Maz, a guided meditation instructor for Open. Key among those are filtering, humidifying, and regulating the temperature of the air as we breathe.

Jessica Phillips, meditation expert and mindfulness-based life coach with P.volve, adds that there is lots of research about the benefits of breathing—and specifically breathing from the nose. "It's how our bodies were designed and why we have a nose (we don't eat from our nose)!" she says.

"Nose breathing is scientifically proven to be the healthiest way to daily breathe. It also helps slow our breathing down, which shifts us out of our 'fight-or-flight' stress response into a place of 'rest and digest,' known as our parasympathetic nervous system," says Maz.

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"Nasal breathing helps us take fuller, deeper breaths, which stimulates a greater distribution of oxygen throughout the body and stimulates the parasympathetic receptors associated with calming the body and mind," adds Phillips.

Both recommend breathing through your nose as much as possible (Maz even recommends mouth taping at night to help train yourself to breathe through your nose while you sleep).

However, that's not to say you should never, ever breathe out of your mouth. "Breathing through your mouth (which we do in Open's Active Breathwork sessions) is used in a short and controlled period of time to shift the dominant parts of the brain giving us access to greater states of release, clarity, and presence," says Maz. Breathing out through your mouth can also help cool your body down, like during exercise.

Downsides of mouth breathing

While breathing through your mouth can be beneficial every now and again—particularly when you need quick relief, say, after a burst of HIIT—double board-certified facial plastic and reconstructive surgeon Dara Liotta, MD, who is also board-certified in otolaryngology, says breathing through your mouth regularly can feel frenzied for the body.

“Airflow through the mouth is quick, voluminous, and chaotic,” she says. “Larger volumes of less organized air that hasn’t had time to be properly warmed and humidified can irritate the airway leading to sore throat, hoarseness, vocal cord irritation, and snoring at night.”

Additionally, she warns that breathing through your mouth can disrupt the balance of bacteria in the mouth and upper airway, which can contribute to developing dental cavities and bad breath.

“Although it may seem like it shouldn’t matter—air is air—breathing through your nose is much better for your body than breathing through your mouth,” Dr. Liotta says. “The nose is a magical thing. Air that enters your body through your nose has been filtered for particles by the small hairs inside the nose, and by the time it hits the deeper airways, it has been warmed and humidified by the many specialized structures inside the nose and by our nasal mucus. Additionally, the nasal passageways (with the nasal septum down the middle) are specially designed to create a calm, laminar flow of air so that it can more easily flow through the lower airway without bouncing around, drying out, and irritating these deeper, more delicate structures.” 

Breathing while sleeping

Now, we know what you’re thinking: Sometimes you can’t control whether or not you have to breathe through your mouth. After all, when dreaded nighttime congestion kicks in, it’s your only option to open your mouth and inhale that way.

ENT Nigar N. Ahmedli, MD, director of the division of facial plastic and reconstructive surgery at Montefiore Medical Center, points out that breathing through your mouth can also be a side effect of living with septal deviation or a crooked nose. Whatever the reason for having to breathe through your mouth when sleeping, the side effects remain the same. 

“Breathing primarily from the mouth causes the mouth and throat to dry out because there is no mechanism to warm and humidify the air (unlike the nose),” Dr. Ahmedli reminds us. “People [who mouth-breathe] typically complain of having a dry mouth and throat, which is most noticeable and bothersome at night.”

The problem with this is—beyond the discomfort—when you have a dry mouth and throat, it disrupts your sleep and can cause you to wake in search of relief from a sip of water. But that’s not the only thing you have to worry about with breathing through your mouth at night. 

“When the nose is blocked, the mouth opens to maximize breathing,” Dr. Ahmedli shares. “Since we sleep lying down, when the mouth opens to breathe, the tongue falls backward against the throat. This may lead to obstruction, or partial closing of the airway, which occurs in sleep apnea.”

That’s not to say that every person who breathes through their mouth while sleeping will develop sleep apnea or even that every person with sleep apnea breathes through their mouth. It’s just a connection, Dr. Ahmedli says.

On the less severe side, mouth breathing at night is a common culprit for snoring, Dr. Ahmedli reveals. “Breathing from the mouth typically results in snoring because the airflow through the mouth and throat is more turbulent, which leads to the sounds produced in snoring,” she explains. 

Interestingly, a small 2022 study in Healthcare that looked at the effect of mouth taping on mouth-breathers with sleep apnea found that “Mouth-taping during sleep improved snoring and the severity of sleep apnea in mouth-breathers with mild obstructive sleep apnea, with the apnea/hypopnea index and snoring index being reduced by about half.”

With this in mind, you may want to consult your doctor about mouth taping if you regularly mouth-breathe while you sleep, and if you’d like to train yourself out of the habit.

Nose vs. mouth breathing while exercising

Now that you know the key differences between mouth breathing vs nose breathing, you may feel like the answer is obvious: You should breathe through your nose while working out, right? In reality, the answer is slightly more nuanced. 

“Ideally during exercise, you should breathe in through your nose (to get all the benefits of warm, humidified, organized, smooth laminar flow of air), and out through your mouth (a quicker, easier exit of air) to allow your body to again breathe in through the nose,” Dr. Liotta reveals. “This maximizes the smooth delivery of oxygen through the nose and the exit of carbon dioxide through the mouth.” 

Imagine running on a cold day. If you breathe in through your mouth, you may find your throat hurts from the exertion. In actuality, it all comes down to the way you’re breathing. It’s all about breath control. And, admittedly, sometimes it requires breathing exercises as part of your warm-up to prepare your body to make the switch from nasal breathing to a combination of both.

That said, if you find it’s difficult to breathe through your nose while working out, Dr. Liotta says you might have bigger issues to think about than the debate of nose breathing vs mouth breathing during exercise. 

“When people feel that they can breathe well enough through their nose at rest, but during exercise, when deeper nasal breathing is required, they can’t breathe through their nose, or the side walls of the nose collapse in, this can be an airway problem called ‘nasal valve collapse,’” she says. “It happens when the side walls of the nostril or bridge of the nose are too weak to properly support deeper nasal breaths.”

While seemingly alarming, it’s nothing to panic over, Dr. Liotta says. “This can be corrected with nasal surgery called ‘nasal valve reconstruction,’ where the nasal walls are stiffened using cartilage grafts of your own septal cartilage. (I do this extremely often as a board-certified facial plastic surgeon who is also board certified in ENT).” 

The takeaway

At the end of the day, mouth breathing effects and nose breathing benefits make the winner of the mouth breathing vs. nose breathing debate obvious. In summary: "Think: nose = calm, and mouth = short periods of controlled breathing for cathartic, deep release," says Maz. 

If you feel you have trouble breathing through your nose, though, Dr. Liotta says to book an endoscopic examination with a board-certified ENT to help diagnose exactly what the anatomic problem is.

—reviewed by Jennifer Gilbert, MD, MPH