A spacer is a device used to increase the ease of giving aerosolized medication from a metered-dose inhaler (MDI).

Some spacers (e.g., InspirEase) utilize a collapsing bag design to provide visual feedback that successful inspiration is taking place.

Another type (e.g., Volumatic) is transparent plastic in two vase-shaped parts that come together forming a barrel shape.

Spacers slow down the speed of the aerosol coming from the inhaler, meaning that less of the asthma drug impacts on the back of the mouth and somewhat more may get into the lungs.

[2][4] In the case of corticosteroids, less residue in the mouth reduces the risk of developing oral candidiasis, a yeast infection.