How to Fix CPAP Mask Leaks (Start by Loosening the Straps)

A leak is not just noise. Air escaping means pressure isn’t reaching your airway, which means the therapy you’re tolerating every night isn’t fully doing its job. It also dries your mouth, blows into your eyes, and wakes your partner.

The good news is that leaks are mechanical, and mechanical problems have causes you can work through in order.

First: know what isn’t a leak

Every CPAP mask has a deliberate vent — a row of small holes that continuously exhausts the carbon dioxide you breathe out. It makes a steady, soft rush of air, and it is supposed to.

If you block it, you rebreathe your own CO₂. Never tape over vent holes, never sleep with a vent pressed into a pillow, and don’t panic about the sound. What you’re troubleshooting is unintended air escaping around the seal.

The diagnostic questions

Where do you feel it? Air in your eyes means the leak is at the top of the mask, at the nose bridge. Air on your cheeks means the sides. A hiss you can hear but not feel is usually the bottom.

When does it happen? From the moment you lie down means a fit or sizing problem. Only after you roll over means position. Only in the second half of the night means the mask is shifting as you relax, or the cushion is warming and softening.

Does your data show it? Your machine reports leak, usually in litres per minute, and most manufacturer apps flag when it’s above the acceptable threshold. That’s the objective version of what you’re feeling. See how to read your CPAP data.

Fix one: loosen the straps

This is genuinely the fix most of the time, and it feels wrong.

CPAP cushions are designed to inflate slightly with the machine’s own air pressure and seal against your skin. Cranked down hard, the cushion is crushed out of its designed shape, the seal breaks somewhere new, and you get a leak and a dent across your face.

Do this:

1. Loosen every strap until the mask is nearly falling off.
2. Lie down in your normal sleeping position.
3. Turn the machine on.
4. Tighten only until the leak stops — then stop.

Fitting the mask standing at a mirror and then lying down is how most people end up with a mask that only works when they’re vertical.

Fix two: replace the cushion

Silicone wears out. A cushion that’s lost its springiness, turned shiny, or feels slightly tacky has stopped sealing and started sticking — and no amount of adjustment brings it back.

Cushions are consumables. Most replacement schedules put them at every one to three months, and insurance typically covers more than people claim. If you can’t remember the last time you replaced yours, that’s very likely your answer. See the replacement schedule.

Fix three: check the size

Mask sizing isn’t standardised across manufacturers, and on many masks the frame size and cushion size are separate choices. People are often one size off and have never been told they could change it.

Signs you’re in the wrong size: a cushion that sits on the tip of your nose rather than around it, one that extends past the crease of your nostrils, or one where you’re forever chasing a leak from the same spot. Most manufacturers publish printable sizing guides. More in the mask sizing guide.

Fix four: deal with your sleeping position

Side and stomach sleepers break their seal against the pillow. Two things help:

A mask where the hose exits at the top of the head, so rolling over doesn’t drag the mask sideways.

A pillow with cutouts that gives the mask and hose somewhere to go instead of levering the seal open.

Fix five: facial hair and skin

Silicone seals against skin, and hair creates channels. A cloth liner between cushion and face closes those channels, and it also helps with skin oils — which are a leading cause of a seal that works at bedtime and fails by 2am.

Washing your face before bed and wiping the cushion each morning does more for leaks than most people expect.

Mouth leak is a different animal

If you use a nasal mask or nasal pillows and your mouth falls open, air takes the shortcut: in through the nose, out through the mouth. Your mask isn’t leaking at all — you are.

Symptoms: waking with a mouth like paper, a loud puffing sound, and high leak readings with a mask that looks perfectly seated.

Fixes, in order of cost: raise humidity, add a chin strap, switch to a full face mask. If you’re congested and can’t breathe through your nose, treat the congestion — that’s a doctor conversation. Full detail in CPAP and dry mouth.

When to stop fiddling and call someone

Call your DME supplier if you’ve worked through this list and still have a leak you can’t resolve, if you’ve got a sore on your nose that isn’t healing, or if you’ve been fighting the same mask for more than a few weeks.

Mask swaps are routine. Suppliers would far rather exchange a mask than have you abandon therapy — and many retailers offer a fit guarantee that lets you exchange a mask that doesn’t work even after use. Ask about it before you buy anything.