Metered dose inhalers (MDIs) are pressurized containers with medicine in aerosol form. The patient must press the canister to activate the propellant (usually Hydrofluoroalkane, or HFA) and inhale slowly for several seconds at the same time.
One page instruction can be found from American Lung Association.
In Spanish:
Using spacer can help the inhalation process and make it easier to inhale the full dose.
In Spanish: