It has two parts: a metal canister that contains the asthma medicine, and a plastic tube that the canister fits into and that helps dispense the medicine into your mouth and airways. When you push on the top of the canister, it releases a metered dose of medicine into the plastic tube and you breathe it in from there.
What you need to know about MDIs
Answers to your questions about MDIs
Step by step guide to using a MDI


