Metered dose inhalers

These inhalers consist of a pressurized canister containing medication that fits into a boot-shaped plastic mouthpiece. With most metered dose inhalers, medication is released by pushing the canister into the boot.

Some types of metered dose inhalers release medication automatically when you inhale. A few metered dose inhalers have built-in dose counters so that you know how many doses remain. Some newer devices use wireless technology to help you count doses by allowing you to track them with an app downloaded to your phone.

If your metered dose inhaler doesn't have a counter, you'll need to track the number of doses you've used or purchase a separate electronic dose counter to tell when the inhaler is low on medication.

For some people, such as for children or older adults, using a spacer or valved holding chamber with an inhaler might make it easier to inhale the full dose. A spacer holds medication in a tube between the inhaler and your mouth after it's released. A valved holding chamber is a specialized spacer with a one-way valve to help regulate the flow of medication.

Releasing the medication into the spacer allows you to inhale more slowly, increasing the amount that reaches your lungs. Spacers and holding chambers require a prescription.