What Is Mouth Breathing? Causes, Effects, and Treatment

Written by Nichole Owens
Medically Reviewed by Poonam Sachdev on July 03, 2025
7 min read

Most people naturally breathe through their noses almost all the time. Humans evolved this way as a survival technique — it allows us to keep breathing as we eat with our mouths, reducing the risk of choking.

But some people can’t breathe through their nose, so they breathe through their mouth. It may be because of the way their body is structured or another issue. Either way, unconsciously breathing through your mouth could lead to other health issues. Here’s what you need to know.

It can be hard to know if you breathe through your mouth, especially if it happens while you sleep. Signs you might be in the habit include:

If this sounds like you, talk to your doctor. There’s not a simple test to diagnose it, but your medical team can do multiple exams to recognize if you breathe through your mouth.

To diagnose mouth breathing, your doctor, usually an orthodontist, will:

Do visual tests. They’ll look at how well your lips seal and check for posture changes, dark eye circles, a long face, an open bite, a high and 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 such as: “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 how to best 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:

More rare causes include:

  • Nasal polyps, which are growths of tissue in the lining of your nose
  • Tumors
  • Genetic abnormalities that affect your nose

Other conditions, such as sleep apnea can cause mouth breathing while you sleep. When a sleep apnea episode happens, you stop breathing. This makes your brain panic, which leads to a loud snore as your body suddenly gasps for air. These events can create a habit of mouth breathing so that your body gets enough oxygen.

Experts agree that breathing through your nose has many more benefits than mouth breathing. The nose processes air differently than the mouth. These differences are our body’s way of keeping us safe and healthy. When you breathe in through your nose, it:

Controls temperature. Your lungs prefer air that’s not too cold and not too hot. Unless you have a block, like a deviated septum or chronic rhinitis, your nose will warm or cool the air that goes into your lungs. This will help the air reach an ideal temperature for your body. Mouth breathing doesn’t do this.

Filters toxins. The small, hair-like structures called cilia in your nose filter out toxins and debris when you breathe. They help send them to your throat instead of your lungs. Mouth breathing directs everything you breathe into your lungs.

Humidifies. Your nasal passages humidify the air you inhale. Your mouth doesn’t typically do this, which is why some mouth breathers wake up with dry mouth or a sore throat.

Sense of smell. Your nose can smell harmful substances in the air or your food. Your mouth can’t find these toxins as effectively.

The only time it’s absolutely necessary to breathe through your mouth is when you’re doing intense exercise or if your nose is blocked from congestion, a cold, or allergies. In these situations, temporary mouth breathing can help you get air to your lungs more quickly.

Breathing through your mouth can dry out your gums and the tissue that lines your mouth. This can change the natural bacteria in your mouth, leading to gum disease or tooth decay.

It can also cause enlarged tonsils, which can lead to snoring and ultimately affect sleep.

Jonelle Anamelechi, a board-certified pediatric dentist and CEO of Children’s Choice Pediatric Dentistry and Orthodontics in Washington, DC, says mouth breathing and many of its effects often start and can be fixed in childhood. If left untreated, they can interfere with growth, development, and learning, causing problems later in life.

“When we have that going on for a prolonged period of time, growth is not ideal, breathing is not ideal, constant colds, coughs, congestion, germs and bacteria that aren’t ideal, then we have an adult who starts to suffer from those things.”

And that’s not all. Anamelechi says that over time, mouth breathing can actually change the shape of your face. “When your mouth is open, your jaw starts growing down, and that is not the way the jaw is supposed to grow.”

This can lead to physical changes in children, such as:

  • An elongated face
  • Droopy eyes
  • Dark spots underneath the eyes
  • Narrow nostrils
  • Trouble sealing lips
  • Dry lips
  • A narrowed upper lip
  • A forward open bite

If the shape of your nose or face is the cause of your mouth breathing, you might not be able to treat it directly.

But if an underlying condition causes mouth breathing, your doctor will want to treat that first. Doing so might help you breathe through your nose better.

For example, you might need to take allergy medicine, or if you have sleep apnea, your doctor will suggest treatments based on how mild or severe your case is.

For moderate sleep apnea, your care team may advise you to lose excess weight, avoid alcohol and certain sleeping pills, use special pillows, or take medication for sinus issues and congestion.

For more intense cases, you might need to wear a special mask over your nose or mouth while you sleep. This therapy, called continuous positive airway pressure (CPAP) therapy, gently pushes air through your nose or mouth to prevent your upper airway tissue from collapsing.

You can also try some preventive measures at home:

  • Practice breathing in and out through your nose.
  • Keep your nose clean.
  • Reduce stress so you don’t gasp for air with your mouth.
  • Use a larger pillow to prop your head up when you sleep.
  • Exercise.

Anamelechi says treatment for children struggling with mouth breathing often requires more than one method. This may involve ear, nose, and throat specialists, pediatricians, myofunctional therapists, and orthodontists.

Mouth breathing means you breathe through your mouth, rather than your nose. This can happen for simple reasons, such as being sick and having a stuffy nose, or it may be due to a condition, such as sleep apnea. Sometimes, mouth breathing begins at birth due to your body’s structural makeup. Symptoms of mouth breathing can be short-term (dry mouth, bad breath, hoarseness) or long-term (changes to your face or posture). If you’re concerned about mouth breathing, talk to your doctor about treatment.

What are the effects of mouth breathing?

Short-term effects of mouth breathing include dry mouth, bad breath, hoarseness, and feeling tired when you wake up. This is likely caused by a lack of restful sleep. Long-term effects of mouth breathing can include constant colds and tooth decay. This happens because germs and bacteria in the air, which are normally filtered by fine, hair-like structures in your nose (cilia), are trapped in your mouth.

Over time, mouth breathing in children can lead to changes in the structure of their face.

How do I stop breathing through my mouth while I sleep?

Talk to your doctor if you believe you breathe through your mouth while you sleep. You may have a condition, such as sleep apnea, that needs treatment. You should also make sure your nasal passages are clear before bed, and if you have allergies, take medications to treat them. Finally, you can try propping your head up with extra pillows at bedtime. This may help you breathe better.

Is mouth breathing bad?

In the short term, it’s probably not. If you have a stuffy nose due to allergies or sinus problems, you may find that the only way you can breathe is through your mouth. But in the long term, mouth breathing can cause serious problems, such as tooth decay, gum disease, snoring, and poor sleep. It can also change your facial features and lead to ongoing respiratory problems, such as colds and flu. 

What does “mouth breather” mean?

A mouth breather is someone who breathes through their mouth because they can’t take in enough air through their nose. This could be due to congestion caused by a cold or sinus problem. It could also be due to structural problems, such as a deviated septum or swollen adenoids — glands located above the roof of the mouth, behind your nose.