CPAP · Troubleshooting

CPAP mask leaking? Common causes and how to fix them

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A hissing mask, air blowing in your eyes, or a partner nudging you because of the noise: mask leaks are one of the most common CPAP complaints. The good news is that most leaks have a simple cause, and many can be fixed at home.

Why leaks matter

A small amount of air escaping through the mask's built-in vent is normal. That's how the mask clears the air you breathe out. An unintentional leak, where air escapes around the edges of the cushion or out of your mouth, is different. It can:

  • reduce the pressure reaching your airway, so your therapy may not work as well
  • dry out your eyes, nose or mouth
  • make noise that wakes you or your partner
  • make you more likely to pull the mask off during the night

Many CPAP machines record leak data. Check your machine's display or app in the morning to see how your mask performed overnight.

8 common causes, and what to try

1. The headgear is too tight

It sounds backwards, but over-tightening is one of the most common causes of leaks. Pulling the straps hard squashes the cushion out of shape and can create new gaps, as well as red marks on your skin.

Try: loosen the straps until the mask just seals. You should be able to slide a finger under the straps.

2. The mask isn't seated properly

Masks behave differently when you're lying down with air flowing than when you're sitting up.

Try: fit your mask while lying in your usual sleeping position with the machine running. Gently pull the mask straight away from your face, then let it settle back. This lets the cushion inflate and re-seat. Check your mask's instructions for the recommended fitting steps.

3. The cushion is worn out

Silicone and gel cushions break down with use and skin oils. An old cushion goes stiff, shiny or sticky and stops sealing well, even if the mask fitted perfectly when it was new.

Try: replace the cushion according to the manufacturer's schedule, or sooner if it looks or feels worn.

4. Skin oils and moisturiser

Face creams, oily skin and a dirty cushion can stop the seal from gripping.

Try: wash your face before bed, and skip moisturiser where the cushion sits. Clean the cushion as the manufacturer recommends, usually with warm water and mild soap. Avoid harsh cleaners or anything scented.

5. Wrong mask size or style

Faces change, and mask designs vary a lot. A mask that's the wrong size or shape for your face may never seal well, however you adjust it.

Try: a mask fitting. Trying different sizes and styles in person, while lying down, is the most reliable way to find a better match. Read about mask styles.

6. Your mouth falls open (with a nasal mask or pillows)

If you use a nasal mask or nasal pillows and your mouth opens during sleep, air escapes through your mouth. You may wake with a very dry mouth.

Try: a chin strap, or ask about switching to a full face mask. Treating a blocked nose (talk to your GP) can also help you breathe through your nose.

7. Your pillow or sleeping position pushes the mask

Side and stomach sleepers often find the pillow nudges the mask out of place.

Try: a lower or softer pillow, or a CPAP pillow with cut-outs. Making sure the tubing has some slack (for example, looping it over the bedhead) stops it tugging on the mask when you turn over.

8. Changes to your face

Weight gain or loss, new dentures, taking dentures out at night, or growing a beard can all change how a mask sits.

Try: a refit after any of these changes. Some people with beards do better with nasal pillows or a different style of mask.

What about the pressure? Leaks can be worse at higher pressures, but please don't change your prescribed pressure settings yourself. If you think your pressure may need adjusting, talk to your doctor. We can share your machine data with them.

Quick leak checklist

  • Headgear snug, not tight
  • Mask fitted lying down, with the machine running
  • Cushion clean and not worn
  • No moisturiser where the cushion sits
  • Tubing has slack and isn't pulling
  • Mouth closed (chin strap or full face mask if needed)
  • Right size and style for your face now

When to get help

Book a check if:

  • your machine regularly shows high leak, even after trying these fixes
  • you're getting sore skin, red marks or eye irritation
  • you're taking the mask off during the night or using CPAP less than you'd like
  • you feel as tired as before you started CPAP

At our Kogarah clinic, we can check your mask fit, look at your machine data with you and help you try other masks. Bring your machine, mask, tubing and power cord. More about CPAP support.

This article is general information only and isn't a substitute for advice from your doctor. Always follow the instructions for use that come with your equipment.