spacer

A spacer is a hollow tube or chamber that clips onto a metered-dose inhaler and sits between the inhaler and your mouth. Think of it as a holding room for the medicine: the puff fires into the chamber, slows down, and waits there for a moment so you can breathe it in calmly instead of having to catch a fast spray.

This solves two problems at once. It removes the need to perfectly time the press with the breath, and it lets the largest, fastest droplets settle on the chamber walls rather than slamming into the throat. What remains is a cloud of smaller particles that travels more gently and reaches deeper into the airways, so more drug gets to the lungs and less is swallowed.

Better-designed spacers add a one-way valve so the chamber holds the dose until you inhale and does not let you blow back into it. A spacer is especially valuable for young children (often with a face mask), for older adults, and for anyone during a flare-up when steady, coordinated breathing is hard.