Why a Blocked Nose Makes CPAP So Hard, And Why a Dental Splint May Be the Answer
For people using CPAP therapy to manage obstructive sleep apnoea, a blocked nose is far more than a seasonal inconvenience. It is a direct threat to the effectiveness of their treatment — and in many cases, the reason they stop using their machine entirely. Winter in Australia brings cold and flu season, dry indoor air, and elevated rates of nasal congestion that place CPAP users under particular pressure. Understanding why nasal congestion and CPAP are such a problematic combination — and what the clinically proven alternative looks like — could be the most important thing a CPAP user reads this winter.
How CPAP Works — And Why the Nose Is Central to It
CPAP — Continuous Positive Airway Pressure — works by delivering a continuous stream of pressurised air through a mask to keep the upper airway open during sleep. In its most common form, CPAP is delivered through a nasal mask or nasal pillow that sits over or inside the nostrils, relying entirely on nasal breathing to direct the pressurised air through the airway. Even full-face masks, which cover both nose and mouth, function most effectively when nasal breathing predominates.
When the nose is clear, this system works. When the nose is congested — as it so frequently is during winter — the entire delivery system is compromised from the outset.¹
What Happens When You Try to Use CPAP With a Blocked Nose
Nasal congestion creates a cascade of problems for CPAP users that begins the moment the mask goes on.
The pressurised air from a CPAP machine is being delivered into a system where one of the primary routes — the nasal passages — is partially or completely blocked. The body's instinctive response is to open the mouth and breathe through it instead. For nasal mask users, this means the pressurised air that should be travelling through the airway is instead escaping through the open mouth — a phenomenon known as mouth leak. The result is a dramatic reduction in the effective pressure being delivered, which means the airway is no longer being adequately splinted open. Sleep apnoea events resume, oxygen desaturation occurs, and sleep is fragmented — all while the machine is technically running.¹
Even when a full-face mask eliminates the mouth leak problem, a blocked nose during CPAP creates a different set of issues. The machine must work harder to push air through congested nasal passages, increasing resistance and discomfort. The pressurised air itself — particularly when inadequately humidified in dry winter conditions — can further dry and irritate already inflamed nasal mucosa, worsening the congestion it is trying to bypass. The result is a vicious cycle: the blocked nose makes CPAP uncomfortable, and the CPAP makes the blocked nose worse.²
Research published in scientific literature confirms that nasal congestion is among the most significant factors compromising CPAP compliance — with nasal congestion identified as a particularly prevalent complaint that can seriously undermine adherence to therapy.³ And with winter cold and flu season placing even non-congested patients at risk of regular nasal obstruction, this problem is not a rare edge case. It is a seasonal reality for the majority of CPAP users.
The Compliance Crisis This Winter
CPAP compliance is already a significant challenge in the best of conditions — studies consistently show that between 30% and 60% of patients prescribed CPAP therapy fail to adhere to it long-term.⁴ Winter is widely recognised by sleep clinicians and CPAP suppliers as one of the most difficult seasons of the year for CPAP compliance, with the combination of dry indoor air, seasonal illness, and nasal congestion creating what one provider described as "a recipe for non-compliance."²
For many patients, a winter cold is the event that causes them to remove the CPAP mask for the first time — and never put it back on. The discomfort of trying to use nasal CPAP with a blocked nose, the noise of mouth breathing against the seal, the dry mouth, the disrupted sleep — all of these experiences consolidate into a negative association with the machine that is difficult to reverse. For these patients, the question is not how to manage CPAP through a blocked nose. It is whether a fundamentally different treatment approach might serve them better.
Why a Mandibular Advancement Splint Has a Crucial Advantage
Here is what makes a mandibular advancement splint (MAS) — also known as a mandibular advancement device or oral appliance — fundamentally different from CPAP in the context of nasal congestion: it does not depend on the nose at all.
A mandibular advancement splint works by gently repositioning the lower jaw forward during sleep, mechanically opening the upper airway at the level of the tongue base and soft palate. This action stabilises the airway directly, reducing collapsibility and preventing the tissue vibration that causes snoring and the airway collapse that causes obstructive apnoea events. It requires no airflow delivery system, no mask, no tubing, and — crucially — no requirement for the nose to be clear and functional.⁵
Whether the patient is breathing through their nose, through their mouth, or switching between the two as their congestion comes and goes throughout the night, the oral appliance continues to work. The jaw is held forward regardless of nasal patency. The airway remains mechanically stabilised regardless of what the nose is doing. For patients who struggle with nasal congestion — seasonally or chronically — this is not a marginal advantage. It is a clinically meaningful one that directly addresses the scenario in which CPAP fails most frequently.
The Evidence for Oral Appliance Therapy
The clinical evidence supporting mandibular advancement splints as a frontline treatment for snoring and obstructive sleep apnoea is substantial. Custom oral appliances have been shown to be over 92% effective in treating sleep apnoea, and are endorsed by both the Australian Dental Association and the Australasian Sleep Association as a recommended treatment for patients who cannot tolerate CPAP or who prefer a less intrusive option.⁵ Research consistently demonstrates that the superior compliance rates achieved with oral appliances — driven by their comfort, portability, and simplicity — mean that effective nightly use is far more achievable for many patients than with CPAP, even when CPAP is theoretically superior in controlled conditions.⁵
Critically, the benefits of oral appliance therapy extend beyond snoring reduction. Studies confirm that mandibular advancement splints produce meaningful improvements in AHI (the measure of sleep apnoea severity), daytime sleepiness, blood pressure, and quality of life — and that these gains are maintained over the long term in compliant patients.⁵
Who Should Consider Switching?
If you are a current CPAP user who finds that winter colds, sinus problems, allergic rhinitis, or nasal congestion regularly disrupt your ability to use your machine effectively, a conversation with a sleep medicine dentist about oral appliance therapy is well overdue. You should not have to choose between enduring a blocked nose behind a mask all night and abandoning treatment for your sleep apnoea entirely — there is a clinically validated alternative that sidesteps the nasal requirement completely.
If you have never been able to tolerate CPAP — whether due to nasal congestion, claustrophobia, mask discomfort, or any other reason — this winter is an excellent time to explore whether a custom mandibular advancement splint is right for you. Our 80% satisfaction guarantee means you can pursue treatment with confidence, and our comprehensive 12-month review program ensures that your appliance is optimised to deliver the best possible outcome for your specific anatomy and sleep apnoea severity.
Call SleepWise Clinic on 1300 101 505 or take our free online sleep apnoea test today. Your nose may be blocked, but your treatment options are wide open.
Request for references: 1. ResMed UK. 2. CarePro Health Services. 3. Zhao X et al. (2016) . 4. Singhal P et al. (2016) 5. American Academy of Dental Sleep Medicine. 