 [ Symptoms ] how do i keep track of how much medication is in my metered dose inhaler [ Disease ] check the side of the canister for the number of puffs it contains then keep track of how many times you use it each day this way you can estimate when your metered dose inhaler is likely to run out put that date right on the canister be sure to have your prescription refilled one to two days before this date some mdi is contain a color coded side window that indicates when the medication is running out it may be difficult for you to keep track of how much you use your inhaler    perhaps because you only use it every once in a while as a rescue medication if so ask your doctor about mdis that count the puffs each time you press the inhaler or ask about getting two inhalers at a time when one runs out get a refill so you always have an inhaler handy throw away the mdi when it is empty even if it continues to spray