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Question & Answer - Oral Sensory-Motor, Myofunctional, Vocal Tract, & Airway Information

Does mouth-breathing cause large tonsils?

April 2018


Answer from David McIntosh; MBBS, FRACS, PhD; Paediatric ENT Specialist; Associate Professor, James Cook University in Australia

If you search the internet and listen to some breathing retraining professionals, you will see and hear claims that mouth-breathing causes large tonsils. But, if you look at actual published research to verify that claim, it does not exist. There is nothing published in the scientific literature what-so-ever to support the claim. So where did this claim come from?

Well given I have heard this so much, I thought it was time for me to look at my data to see if I could find an answer. I decided to look at it in 3 ways in children under the age of 12 who needed surgery to help them breathe. This involved reviewing over 11 years of clinical practice.

First, I looked at those who presented with large tonsils (grade 3 or 4- see for more information about what this grading system means) and determined what portion of these children were mouth-breathing. Then, I reviewed all of those who had their tonsils removed for breathing problems (so the above plus grade 1 and 2 tonsils) and again looked at who was mouth-breathing and who wasn’t. The third thing I did was to look at it a different way -- I looked at every child who presented with mouth-breathing and required surgery to look at what portion had large tonsils.

Keeping the above process in mind, it’s important to realise something -- I only looked at surgical cases. There were a good number of cases of mouth-breathers who responded to medical therapy and hence did not need surgery. All of these cases had small tonsils. So the numbers presented below do not account for the many mouth-breathers with normal-sized tonsils than what I found in my case review. Therefore, the patients in this study were in a more significant category of obstruction.

So What Did I Find?

Well, over approximately the past 11 years, I operated on 1,979 children where the surgical indication was upper airway obstruction in all of its forms. In terms of those who had surgery that involved removing large tonsils, there were 597 children. Then I looked at how many were mouth-breathing and how many were not. It turns out that 87% of these children were mouth-breathers. So, we can suggest that mouth-breathing is very common in those with large tonsils in the patients for whom I have cared. But, the catch here is whether mouth-breathing causes large tonsils or whether large tonsils cause mouth-breathing.

So next, I looked at those with small tonsils that came out due to airway obstruction. There were 121 cases. Of those, 92% were mouth-breathers. So, that’s interesting. Mouth-breathing in children needing airway surgery is pretty common, and the size of the tonsils can be big or small with equal rates (roughly) of mouth-breathing regardless of tonsil size. But, more mouth-breathing occurred with smaller than larger tonsils. When I looked at the mouth-breathers having their tonsils removed, most of them had either big adenoids, large nasal turbinates, or both (learn more here- So far, all we can say is a blocked nose is common in those with tonsils contributing to airway problems. This led me to step 3.

The last thing to do was to flip things around and start with the mouth-breathers to see how many of them had large tonsils. Now, as mentioned previously, this only included surgical cases. If a child presented to me with airway problems and normal-sized tonsils, a good number were candidates for medical therapy and a good number responded favourably. These patients were excluded from this review as it would have taken me months to go through the day otherwise!

I found in 1,896 children who had surgery, mouth-breathing was part of their presentation. 621 or about 33% had their tonsils removed. So, in other words, 67% of the children had surgery for airway obstruction and their tonsils were absolutely fine. I’ve said it before and will do so again, there were actually many more children with normal tonsils than those with large tonsils. I would be guessing, but if I had included all mouth-breathing cases, then that number of 1,896 would probably be doubled. That would theoretically mean 16% of mouth-breathers had their tonsils out. But, since it’s a guess, I’ll leave that speculation open-ended.

Ok. Back to the actual numbers. I’ve got 1,896 mouth-breathers and 621 tonsillectomies. But, what portion actually had large tonsils? The answer is 26%. That’s right. 74% of surgical mouth-breathing cases had normal-sized tonsils. So, the idea that mouth-breathers have big tonsils seems untrue when one looks at the big picture of all mouth-breathers.

So What Does This All Mean?

Well, first of all, mouth-breathing overall does not appear to make tonsils big. Secondly, in those with airway obstruction, where it’s judged that tonsillectomy is indicated, most of the time it’s in association with large adenoids, turbinates, or both. So, whatever makes the tonsils large tends to make the adenoids big as well.

I would propose that whilst mouth-breathing is very common in children struggling with their breathing, when it comes to needing surgery, mouth-breathing itself does not cause large tonsils. In those children with big tonsils, mouth-breathing is more recognised because of nasal obstruction related to co-existing large adenoids (and/or turbinates at times).

If my data is consistent with others who may want to carry out this same exercise, then it may be that people are getting tripped up in their selection bias of those needing tonsils removed happening to be mouth-breathers. If one uses the appropriate starting point of all mouth-breathers, then it can be seen mouth-breathing likely does not lead to big tonsils, especially when one considers the population presented excludes a significant number of mouth-breathers who had normal-sized tonsils and were hence treated with a nasal steroid spray with good effect such that no surgery was required.

I’ve presented this data elsewhere and for those with an agenda regarding the maladies of mouth-breathing, it received a cold reception. But, for those seeking a better understanding of why tonsils become large, this may well be a step in the right direction. The inference is that breathing retraining is doomed to fail in many because of a large portion having pathological nasal obstruction (in other words not a habit) and because mouth-breathing does not do anything to the tonsils anyway, so stopping it does not make them better either. Persistent mouth-breathing is an unhealthy practice, but we need to be clear about why it’s happening. And, it’s usually nasal obstruction.

About the Author

Associate Professor Dr. David McIntosh of ENT Specialists Australia was kind enough to write this month’s question and answer. He also contributes to Facebook groups collaborating with other specialists who manage breathing problems in children. They talk about mouth-breathing, and how it can lead to serious health concerns, in the hope that parents will take a proactive role in finding breathing problems in their own children and insist doctors take their concerns seriously.

David is a Paediatric ENT Specialist with a particular interest in airway obstruction, facial, and dental development and its relationship to ENT airway problems and middle ear disease. He also specialises in sinus disease and provides opinions on the benefit of revision of previous sinus operations. He is passionate about Indigenous Health. And, he has undertaken advanced surgical training in ENT and Head and Neck Surgery and Paediatric training at Starship Children’s Hospital in Auckland, New Zealand. He is the author of Snored to Death: Are You Dying in Your Sleep?

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