“But nose breathing isn’t a cure-all. It’s something most of us do naturally. One exception is if we’re running – the nose has more resistance to airflow so it’s easier to get more oxygen in quickly by breathing through the mouth.”

We all become mouth breathers sometimes if we have a blocked nose from a cold, for instance, but if you’re among the minority of people who mouth breathe most of the time, or during sleep, it’s best to find the cause and treat it – not reach for the sticky tape, says King.

“The usual reason for mouth breathing is some obstruction to the nose – common causes are allergies or structural problems like a deviated septum, where the cartilage separating one nostril from the other is in the wrong position,” he says.

“In children it could be because of the size of their adenoids (lymph nodes at the back of the nasal cavity in kids). People with asthma have a higher prevalence of mouth breathing but it’s not clear whether asthma causes the mouth breathing or whether mouth breathing causes the asthma. ”

Mouth breathing at night can also be caused by sleep apnoea where the muscles of the throat relax so much that they restrict the amount of air reaching the lungs. It’s exacerbated by sleeping on your back, drinking alcohol and being overweight – fat deposits around the neck can narrow the airway during sleep, while fat around the middle can encourage mouth breathing, King explains.

“Losing weight, even just some of the weight, can be enough to improve sleep apnoea and mouth breathing.”

As for clues that you’re mouth breathing at night, regularly waking up with a dry mouth is a reliable sign – and that can lead to dental problems.

“Mouth breathing can dry out the mouth - saliva protects the teeth so if there’s a deficiency of it, teeth can be more susceptible to decay,” explains oral medicine specialist Dr Amanda Phoon Nguyen, a spokesperson for the Australian Dental Association.

“You have to interpret the research with caution. I think there’s some scaremongering going on. If parents are concerned about a child’s mouth breathing, check to see what’s going on.”

“There are also concerns that, with children, mouth breathing causes crowding of the teeth and problems with facial development, but it’s controversial because so many variables, including the individual growth of children, can make this difficult to study. You have to interpret the research with caution.

“I think there’s some scaremongering going on. If parents are concerned about a child’s mouth breathing, check to see what’s going on – but if a dentist or doctor suggests an expensive treatment, a second opinion might be a good idea.”


Alarming claims about mouth breathing causing problems with children’s facial development, behaviour and learning aren’t new to Dr Chris Seton, Paediatric and Adolescent Sleep Physician with the Woolcock Institute.

“But only 5 to 6 per cent of children are mouth breathers. Prime time is around the age of three when tonsils and adenoids are at their peak growth and may make it harder to breathe through the nose. But by five they’ve usually shrunk a bit and the problem disappears.

“Good GPs know that not all mouth breathing or snoring in children is a problem. If there are concerns, a referral for a sleep study at a sleep clinic can check if there’s a blockage or sleep apnoea. Only around a third of children who are referred need treatment – 70 per cent don’t. ”

Although there are overnight mouth taping products available, Seton wouldn’t recommend it for kids or adults.

“If someone has a blocked nose, taping their mouth can lower their oxygen levels even more so they wake up more often.”

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