What Is a Breath-Actuated Metered Dose Inhaler?

A breath-actuated metered-dose inhaler (MDI) is a type of inhaler that delivers asthma medication directly to the lungs. With this type of MDI, it's your inhalation combined with a propellant that gets the medication where it needs to go rather just than a propellant, as is the case with a conventional MDI.

When using a breath-actuated MDI, proper technique is important for making sure the entire dose of medicine reaches your lungs.

Woman using Asthma inhaler in garden
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Breath-actuated MDIs are sometimes simply called breath-actuated inhalers (BAIs), while conventional MDIs may be called pressurized MDIs (pMDIs).

How to Use a Breath-Actuated MDI

Before you begin using a breath-actuated metered-dose inhaler, be sure you are clear on the instructions you've been given. The effectiveness of a pMDI hinges on the medication actually getting to your lungs, and that depends on using the inhaler correctly.

Your healthcare provider, pharmacist, or asthma educator should be able to demonstrate the proper technique and help you become comfortable with it. If you unsure of what to do, just ask.


Some BAIs require priming—spraying one or more puffs when the inhaler is new or hasn't been used for a certain period of time. This requirement varies among devices. Check with your healthcare provider or refer to the package insert for specific instructions on priming your inhaler.


These are general instructions on how to use a breath-actuated metered-dose inhaler. Those that come with your inhaler may vary slightly.

  1. Remove the cap from the mouthpiece and shake for 5 seconds. This is important for ensuring you get the full and proper dose of medication.
  2. Hold the inhaler upright and lift the lever. Prime your inhaler, if necessary.
  3. With your mouth away from the spacer, breathe out completely.
  4. Lift your chin slightly and place the mouthpiece into your mouth, sealing your lips tightly around it.
  5. Breathe in slowly through your mouth for about 5 seconds. As you inhale, the MDI will release a puff of medicine.
  6. Fill your lungs as completely as possible. Hold your breath and slowly count to 10.
  7. Slowly exhale.
  8. Close the lever.
  9. Repeat steps 3 through 8 as many times as necessary to get the appropriate dose, as prescribed by your healthcare provider.

Asthma Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

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How Long a BAI Lasts

To figure out how long your inhaler will last, divide the total number of doses the inhaler contains (found on the canister or package insert) by how many doses you use in a day.

For example, if your inhaler contains 200 doses and you take one puff twice daily, it should last you100 days.

When you've used the total number of doses, dispose of the canister. It may feel as though there is still medication inside the inhaler, but this is most likely a chemical additive or leftover propellant.

Be sure to order a refill before you run out of medicine. If you rarely use your inhaler, be sure to keep an eye on the expiration date so you can order a new one ahead of when you may need it.

Your inhaler should last for several months with proper use and cleaning.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  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. 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

Additional Reading

By Pat Bass, MD
Dr. Bass is a board-certified internist, pediatrician, and a Fellow of the American Academy of Pediatrics and the American College of Physicians.