CPAP Machine Filters

CPAP Filter Guide

Does my CPAP machine have one filter or two?

Many CPAP machines use a two-filter system — a reusable foam or pollen filter on the outside, and a thin disposable fine filter tucked behind it. The ResMed AirSense 10 and AirSense 11 are good examples: they take a grey reusable foam filter as the outer layer, with an optional hypoallergenic disposable filter behind it. The Philips DreamStation similarly uses both a reusable blue pollen filter and a disposable ultra-fine white filter. Check your machine's user guide or use the sidebar filters on this page to find the correct filter type — ordering only one when your machine needs two is the most common purchasing mistake in this category.

What's the difference between a standard and hypoallergenic CPAP filter?

Standard filters catch dust, pet dander, and general airborne particles — they're sufficient for most users in typical home environments. Hypoallergenic filters have a finer filtration layer that also captures smaller particles such as pollen, mould spores, and fine dust. They're recommended for users with allergies, asthma, or respiratory sensitivities, or for anyone using their machine in a dusty environment. Hypoallergenic filters are disposable and should not be washed — rinsing them damages the fine filtration layer and renders them ineffective.

How often should I replace my CPAP filters?

Replacement frequency depends on the filter type. Disposable fine and hypoallergenic filters should be replaced every two to four weeks — check the filter at each clean and replace it sooner if it appears grey or discoloured. Reusable foam and pollen filters can be rinsed under warm water and air dried, but should still be replaced every one to three months as the foam degrades. Running a clogged filter restricts airflow and increases wear on your machine's motor, making filter maintenance one of the most important — and most overlooked — parts of CPAP care. For a full overview of machine cleaning and maintenance, see our CPAP cleaning and care guide.