Metered Dose Inhaler (MDI)

This type of inhaler uses a small canister of medicine inside a plastic holder. The medicine in the canister is under pressure. As you press on the canister, a small burst ("a metered dose") of medicine is sprayed out of the canister. Most people call this a "puff" of medicine.

Your doctor may tell you to use one or two puffs for each dose. If you use two puffs, it is important to take them one at a time. Because the medicine is sprayed out in a very fast burst, it can be difficult to use the inhaler correctly to get the medicine into the lungs. Using a spacer will help. For small children and infants, spacers that have a soft mask attached can be used so the medicine can be breathed in easily. In a situation when you would need to use an inhaler without a spacer, do the following:

1. Remove the cap and hold the inhaler upright.
2. Shake the inhaler.
3. Tilt your head back slightly and breathe all of your air out slowly.
4. Hold the inhaler in one of these ways:
• Open your mouth and hold the inhaler one to two inches away.
• Use a spacer and put the spacer mouthpiece in your mouth.
• Hold the inhaler between your lips.
5. Start to breathe in* and press down on the top of the inhaler canister to spray one puff of the medicine.
6. Breathe in slowly and deeply for three to five seconds to get the medicine into your breathing tubes and down into your lungs.
7. Hold your breath for 10 seconds.
8. If you need to take a second puff, wait one minute and repeat the steps.

*It's important that you are breathing in as you spray (or puff) the medicine into your mouth. If you are not breathing in, the medicine settles on your tongue and inside your mouth, and very little gets into your breathing tubes.

Since you can't see how much medicine is left in the canister, you need to know how many puffs a canister holds.

• Look on the side of the canister or in the package insert that comes with the inhaler and find the total number of puffs (called doses) the canister contains.
• Divide the total number of doses in the canister by the total number of puffs you use each day to know how many days the canister will last.
• Count out the days on a calendar and note the date the canister will run out of medicine.


• Write this date on the canister or on the calendar so you remember to get a refill one week before.
• This only works for regular controller medicines.

For rescue inhalers, try to keep a record of the number of puffs you have used (for example, make a mark on the calendar for each time you use it) so you will have some idea about how soon you will need a refill. Don't wait until the canister is empty before getting a refill.

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