Common errors made by patients using an MDI include:
a) Not shaking the canister or container before each dose
b) Inhaling at the wrong time (not in sync with pressing the inhaler)
c) Aiming the inhaler at the roof of the mouth or tongue, rather than the throat
d) Inhaling an unnoticed foreign body that has entered an uncapped inhaler; damaged or sticky spacer valves that limit the delivery of the medicine