Why CPAP Pressure Can Feel Different When Your Nose Is Blocked or Inflamed

Blocked or inflamed noses don’t just make CPAP therapy uncomfortable. They can change how much pressure actually reaches your airway during sleep.

Many people notice that their CPAP feels different during colds, allergy seasons, bushfire smoke events or temperature changes. This article explains why the same CPAP pressure can feel very different at different times of year, and what you can do to stay comfortable and well supported.

Why the same CPAP pressure doesn’t always feel the same

Your CPAP machine is set to deliver a pressure that keeps your airway open and prevents obstructive sleep apnoea (OSA) events. Once that pressure is set, it often stays the same for long periods.

However, your nose does not stay the same.

Nasal tissues naturally swell and narrow in response to:

When the nose becomes congested, airflow meets more resistance on its way to your throat. That means the pressure measured at the mask may not be the same pressure supporting your airway deeper inside.

As a result, a CPAP setting that felt comfortable and effective a few weeks ago may suddenly feel:

Research also shows that OSA severity itself can fluctuate across the year, particularly during warmer periods. For Australian CPAP users, this helps explain why therapy often feels easier in some months and more challenging in others, even when the device settings have not changed.

How a blocked nose affects CPAP pressure (in simple terms)

CPAP machines measure pressure at the mask, not at the back of your throat where airway collapse happens in OSA.

When the nose is clear, pressure travels smoothly from the machine to the airway. When the nose is blocked, some of that pressure is lost along the way.

A helpful way to picture this is like a garden hose:

This effect is strongest when you breathe in, which is also when obstructive events tend to start. So during a cold or allergy flare, your CPAP may still be delivering the same pressure at the mask, but your airway may not be receiving the full benefit.

Allergies and sinus conditions: who notices changes the most?

Not everyone experiences nasal changes in the same way.

People with allergic rhinitis (hay fever) or chronic sinus inflammation often notice bigger swings in CPAP comfort across the year. These noses tend to be more sensitive to airflow, temperature and humidity changes, which can make congestion linger or worsen with CPAP unless it is actively managed.

For many people without allergies, nasal congestion improves over time with CPAP therapy. But for those with ongoing nasal or sinus conditions, congestion may persist or fluctuate unless the nose itself is treated alongside CPAP.

Increased nasal resistance can also make the upper airway more collapsible. If you have to breathe harder to pull air through a blocked nose, more negative pressure is created in the throat, increasing the risk of airway collapse. This is why nasal health plays such an important role in how effective CPAP feels.

An Australian perspective: seasons, smoke and respiratory illness

Australia’s environment adds extra challenges for CPAP users.

Hot nights, humidity and seasonal changes can already disrupt sleep. On top of that, many Australians experience:

Each of these can irritate the nasal passages and increase congestion for weeks at a time. This means your nasal resistance, and the effective pressure reaching your airway, can change significantly throughout the year.

If CPAP suddenly feels different, it does not automatically mean something is wrong with your machine. Often, it reflects temporary changes in your upper airway.

Signs your nose may be blocking CPAP pressure

Your CPAP data and symptoms can give helpful clues. Common signs include:

These changes often settle once nasal congestion improves. Recognising this pattern can help you respond early and avoid unnecessary frustration with therapy.

Using CPAP during colds, flu or COVID-19

When you are unwell, it is natural to question whether you should keep using CPAP. In most cases, CPAP should not be stopped unless your doctor specifically advises it.

Instead, focus on supporting your nose and comfort:

Continue CPAP if it has been deemed safe for you
Increase humidification to reduce dryness and irritation
Consider a temporary switch to a full-face mask if nasal breathing is difficult
Use saline sprays or rinses to ease congestion
Use short-term decongestant sprays only on advice from a pharmacist or GP

Good hygiene is also important during infections:

Research has shown that CPAP use itself does not increase the risk of respiratory infections when proper cleaning and precautions are followed.

Managing allergies and sinus issues to protect CPAP therapy

For many people, nasal care is just as important as CPAP care.

If you have hay fever or chronic sinus issues, a proactive plan may include:

Simple home strategies can also help:

For some people, referral to an ENT specialist may be helpful if nasal obstruction is persistent. Improving nasal airflow can make the same CPAP pressure more effective and more comfortable.

Creating a seasonal CPAP plan

Because nasal conditions and environments change, CPAP works best when managed as an ongoing process rather than a one-time setup.

Helpful steps include:

Monitoring CPAP data and symptoms across seasons
Preparing ahead for known allergy or smoke periods
Having a clear plan for illness, including mask options and humidification adjustments
Staying in touch with your sleep clinic if patterns repeat year after year

With the right support for your nose, CPAP therapy can remain effective and comfortable year-round, not just on your best breathing days.

Need help with your CPAP setup or nasal comfort?

If your CPAP pressure suddenly feels different, or you’re struggling through colds, allergies or seasonal changes, you don’t have to figure it out on your own.

The team at Sleep Healthcare Australia can help you:

Support is always individual, practical and based on how you’re actually sleeping.

Find your nearest Sleep Healthcare clinic or get in touch with our team

References

1.Wakayama T, et al. Effect of nasal obstruction on continuous positive airway pressure treatment: computational fluid dynamics analyses. PLoS One. 2016.
2.Bratbak DF, et al. Association of allergic rhinitis with change in nasal congestion in new continuous positive airway pressure users.
JAMA Otolaryngology–Head & Neck Surgery. 2020.
3.Ayappa I, et al. Nasal resistance and inflammation as mechanisms in obstructive sleep apnoea. Journal of Clinical Sleep Medicine. 2024.
4.Obstructive sleep apnoea severity varies by season and environmental factors. Communications Medicine (Nature). 2025.
5.Respiratory infection risk in positive airway pressure therapy users. Journal of Clinical Sleep Medicine. 2023.
6.Sleep Healthcare Australia. Continuous Positive Airway Pressure (CPAP) patient information.
7.Sleep Healthcare Australia. Long-term effects of CPAP use and how to manage them.
8.Sleep Healthcare Australia. COVID-19 and CPAP therapy: how to safely continue treatment.
9.Sleep Healthcare Australia. How CPAP works.

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