Metered-Dose Inhaler (MDI)

A metered-dose inhaler, also called an MDI, contains pressurized medicine in a small canister. The canister fits into a plastic sleeve and connects to a mouthpiece. The MDI launches the medication through your mouth and throat into the airways of your lungs. MDIs can be used to administer inhaled corticosteroids, bronchodilators, or a combination of asthma medicines.

For an inhaler to be effective, it's imperative that you use it correctly. Each dose of the inhaler is often prescribed as a specific number of inhalations, or puffs. When your provider first prescribes your inhaler, ask for a demonstration on how to use it properly.

View a demonstration on how to use a metered-dose inhaler.

The basic steps for using most inhalers include:

  1. Remove the cap and hold the inhaler upright.
  2. Gently shake the inhaler.
  3. Tilt your head back slightly and breathe out slowly.
  4. Depending on your provider's specific instructions, open your mouth with your head one to two inches away from the inhaler or position the inhaler in your mouth.
  5. Close your mouth around the mouthpiece of the inhaler. Press down on the inhaler to release medication as you start inhaling or within the first second of inhaling; continue inhaling as you press down on your inhaler. Breathe in slowly through your mouth, not your nose, for three to five seconds. Press your inhaler only once while you’re inhaling (one breath for each puff). Make sure you breathe evenly and deeply.
  6. Hold your breath for 10 seconds to allow the medicine to reach deep into your lungs.
  7. Repeat puffs as your prescription dictates. Waiting one minute between puffs enables the inhaler device to draw up another full dose of medication.

The label on your inhaler will list the maximum number of doses of medication contained in the canister. It's important that you not use your inhaler beyond that maximum number, because as the canister gets close to empty, the amount of medication administered can become irregular.

Here’s a tip for keeping track of when it’s time to start a new inhaler: If you use your inhaler daily for a set number of scheduled inhalations, you can predict when you will use up the maximum number of inhalations in your device. Divide the number of puffs used per day by the number of puffs in your canister. This will give you the number of days that your canister can be used. Calculate the date that the maximum number of doses will be reached, and write that on the canister. This will remind you of when you will need to throw away your old canister and start a new one.