Nose breathing vs mouth breathing: what the evidence says

Nose breathing vs mouth breathing: which is better?

At rest, your nose. It’s built for the job: hairs and mucus catch dust, and the curled passages inside warm and moisten the air before it reaches your lungs. Your mouth is a wider, shorter path. It moves more air, faster, which is exactly what you need halfway up a hill, and less of what you need on the sofa.

What are the benefits of nose breathing?

Three come from the nose itself. It cleans the air, it conditions it, and it adds a little nitric oxide, a gas your sinuses make all the time. Healthy sinuses produce it continuously, and it’s carried in with every breath through the nose (Lundberg 2008).

A fourth comes from the shape of the path. Because the nose is narrower, nose breaths tend to be slower and smaller. That makes it the easy route into the kind of breathing this library is about: lower, slower and softer.

What does the research say?

In one crossover trial, 20 young adults breathed only through the nose for 5 minutes and only through the mouth for 5 minutes. Nose breathing was linked to lower diastolic and average blood pressure and a bigger “rest” signal in heart rhythm. Systolic pressure and heart rate didn’t differ, and the differences were modest (Watso et al. 2023).

In a study of brain recordings, breathing in through the nose kept the brain’s smell, memory and emotion areas in step with the breath, and the effect faded with mouth breathing. Volunteers also recognised fearful faces faster while breathing in through the nose (Zelano et al. 2016). It was a small study of natural breaths in short lab tasks, not of a breathing practice.

So: a sensible default with small, real effects, not a treatment. Nose breathing is also at the heart of Breath by James Nestor, and it’s one of the book’s claims that fits the research.

How well each breath is studied

• Coherent breathingWell studied
• Humming bee breathSome evidence

Every study on this page (6)

• Lundberg, 2008: The paranasal sinuses continuously produce nitric oxide, which is inhaled with each nasal breath and reaches the lungs in diluted form.
• Watso et al., 2023: In 20 young adults, breathing through the nose rather than the mouth slightly lowered blood pressure and raised heart-rhythm signs of calm.
• Zelano et al., 2016: In a small study, natural nose breathing paced the brain's emotion and memory areas, and recall was sharper on the in-breath.
• Zhao et al., 2021: A meta-analysis of 10 studies found that mouth-breathing children had backward and downward rotation of the jaws and narrower airways than nasal-breathing children.
• Chaddha et al., 2019: Across 17 trials in people with high or borderline-high blood pressure, regular slow breathing modestly lowered blood pressure, though results varied.
• Weitzberg & Lundberg, 2002: Humming raised nitric oxide in the nose 15-fold compared with breathing out quietly, in 10 healthy people; health effects weren't tested.

Is mouth breathing bad for you?

Not as an occasional thing. Everyone breathes through their mouth on a run, with a cold or when laughing. It’s habitual mouth breathing, day and night, that’s worth a look. It can leave you with a dry mouth and a sore throat in the morning, and it goes hand in hand with snoring.

Often the mouth is the symptom rather than the cause: a nose that’s blocked by allergies or a bent septum, or in children, large adenoids or tonsils. In children who habitually breathe through the mouth, studies link it to differences in how the jaw and face grow (Zhao et al. 2021), which is why a long-term open mouth in a child is worth mentioning to the GP or dentist. If it’s you, how to stop mouth breathing starts with the nose, then the habit, then the night. For the habit, a few slow minutes a day with Breathform, lips together, is an easy start.

Does nose breathing lower blood pressure?

A little, and for a moment, in the one small trial above: diastolic pressure was slightly lower during 5 minutes of nose breathing than mouth breathing (Watso et al. 2023). That’s a nudge, not a treatment. Regular slow breathing has more behind it: in a review of 17 trials in people with raised blood pressure, it was linked to modest drops (Chaddha et al. 2019). It’s easiest through the nose, and there’s more in breathing exercises to lower blood pressure.

Does nose breathing increase nitric oxide?

Yes, in the sense that it carries your sinuses’ nitric oxide into your airways, while mouth breathing skips it. Humming moves even more: in a small lab study, nasal nitric oxide rose 15-fold while people hummed compared with breathing out quietly (Weitzberg & Lundberg 2002). Nobody has shown what that means for health yet. Humming is still a lovely, slow out-breath: humming bee breath shows you how.

Should you breathe through your nose when exercising?

At an easy pace, try it: a walk, a gentle jog or a bike ride with your mouth closed is a good way to practise. As the effort rises, your body will open your mouth for you, and that’s fine. Nobody needs to nose-breathe a sprint. There’s a pacing guide in how to breathe while running.

Why does Breathform say “in through the nose”?

Because slow breaths are easiest that way. Through the nose, a 5-second in-breath feels natural; through the mouth, it tends to turn into a gulp. So our guides say “in through the nose”, and leave the out-breath to you: nose or soft lips. Here’s the simplest version to try now.

Questions people ask

Can you train yourself to breathe through your nose?

Usually, yes, if your nose is clear. Start in the day, when you can notice: lips together, tongue resting on the roof of your mouth, slow breaths in and out through your nose. A few minutes of slow nose breathing a day builds the habit, and easy walks with your mouth closed help too. If your nose always feels blocked, that’s worth a check with a GP first.

Why does one side of my nose feel blocked?

That’s usually the nasal cycle. The lining inside your nose swells a little on one side and shrinks on the other, and the two sides swap over through the day. Most people never notice it until they pay attention to their breathing. If one side is blocked all the time, or both are, a GP or ENT doctor can look at why.

Is nose breathing better for anxiety?

It hasn’t been tested head to head for anxiety. What helps is a slower breath with an unhurried out-breath, and the nose makes that easier: it’s a narrower path, so breaths tend to come slower and quieter. If anxiety makes you feel you can’t get enough air through your nose, breathe out through soft lips for a while. Comfort comes first.

Is it OK to breathe out through your mouth?

Yes. Plenty of good breaths use the mouth for the out-breath: the soft “whoosh” of 4-7-8, pursed-lip breathing, a long sigh. Breathing in through your nose and out through gently parted lips is a comfortable way to slow down. The nose matters most for the in-breath, where it filters, warms and moistens the air on its way to your lungs.