CPAP filters are easy to forget — they sit inside the machine, out of sight, quietly doing their job until they don't. A worn-out filter doesn't just reduce comfort; it makes your machine work harder and can push dust and allergens straight into the air you're breathing all night.
The general schedule
- Reusable foam filters: rinse weekly with water, replace every 6 months
- Disposable fine filters: replace every 2–4 weeks
- Both filter types fitted: most modern machines use a reusable foam pre-filter plus a disposable fine filter — check your model's manual, as schedules vary by device
If you live somewhere dusty, near a building site, or with pets shedding indoors, lean toward the shorter end of these ranges.
Signs your filter needs changing now
- The filter looks grey, yellowed, or visibly clogged with dust
- Your machine seems louder than usual
- You're noticing more dust or a stale smell from the airflow
- You can't remember the last time you changed it (a good rule: if in doubt, change it)
Why it matters more than people think
A clogged filter forces your CPAP motor to work harder to pull in air, which can affect the pressure delivered to your mask over time. For a therapy that's meant to run every night for years, a $30 pack of filters is a small cost against keeping the whole setup performing as prescribed.
Keeping on top of it
The easiest approach is to set a recurring reminder — tie it to something routine, like the first of the month, so it's not something you have to remember from scratch each time.