Breath Actuated Metered Dose Inhaler

A breath-actuated metered-dose inhaler (MDI) is a type of inhaler that delivers asthma medication to your lungs. With this type of MDI, the medication is driven into your lungs during inhalation instead of via a propellant, as is the case with other MDIs.

When using a breath attenuated metered-dose inhaler, proper technique is important, as improper use leads to less medication being delivered to your lungs.

Woman using Asthma inhaler in garden
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Using an MDI

Some MDIs require priming or the spraying of one or several puffs when the inhaler is new or has not been used for a certain period of time. This requirement varies among devices. Check with your doctor or refer to the package insert for specific instructions.

It is also a good idea to review the inhaler technique with your doctor, asthma educator, or pharmacy for general and product-specific instructions related to your MDI technique.

  1. Remove the cap from the mouthpiece and shake for five seconds. Failing to shake prior to use leads to unreliable dosing when the medication is released.
  2. Hold the inhaler upright and lift lever. See the previously mentioned info about priming. This step is where priming would be performed if necessary.
  3. Breathe out completely away from the spacer You want your chin slightly elevated as you begin to inhale.
  4. Put the mouthpiece in your mouth and seal your lips around it tightly.
  5. Begin to breathe in slowly through your mouth for about 5 seconds. As you breathe in the MDI will release a puff of medicine.
  6. Fill your lungs as completely as possible. Count to 10 slowly while holding your breath.
  7. Slowly exhale.
  8. Close lever.
  9. Repeat steps 3 to 8 the number of times necessary to get your appropriate dose.

Your inhaler will last for several months, so it is important that it remains in good working order.


Look on your MDI canister or package insert to see how many doses are contained in your MDI. In order to determine exactly how long your inhaler will last, you need to determine how many doses you will use per day and then divide by the total number of doses in the inhaler.

For example, if your MDI contains 200 doses and you take one puff twice daily, that means you will use two doses per day. Dividing 200 by two equals 100, so your MDI should last for 100 days.

When you have used the total doses make sure to dispose of the MDI. It may feel as though there is still medication in the canister, but this is most likely a chemical additive or leftover propellant.

Make sure to call your doctor’s office or the pharmacy for a refill before you run out of medicine.

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Article Sources
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  1. Usmani OS, Lavorini F, Marshall J, et al. Critical inhaler errors in asthma and COPD: a systematic review of impact on health outcomes. Respir Res. 2018;19(1):10. doi:10.1186/s12931-017-0710-y

  2. Newman SP. Principles of metered-dose inhaler design. Respir Care. 2005;50(9):1177-90.

  3. Barbara S, Kritikos V, Bosnic-anticevich S. Inhaler technique: does age matter? A systematic review. Eur Respir Rev. 2017;26(146). doi:10.1183/16000617.0055-2017

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