How to use an inhaler

Alternative names
Metered dose inhaler administration


Metered dose inhalers usually come in 3 pieces:

  • A mouthpiece  
  • A cap that goes over the mouthpiece  
  • A canister full of medication.

Using a metered-dose inhaler (MDI) seems simple, but most patients do not use it the right way. When you use your MDI the wrong way, less medicine gets to your lungs. (Note: Dry powder inhalers require different instructions.)

The following steps are based on instructions from the National Heart, Lung, and Blood Institute.


  • Take off the cap and shake the inhaler hard.  
  • Breathe out all the way.  
  • Hold the inhaler 1 to 2 inches in front of your mouth (about the width of two fingers). Alternatively, place the MDI into a spacer and insert the spacer into your mouth.


  • Start breathing in slowly through your mouth, and then press down on the inhaler one time. (If you use a spacer, first press down on the inhaler. Within 5 seconds, begin to breathe in slowly.)  
  • Keep breathing in slowly, as deeply as you can.


  • Hold your breath as you count to 10 slowly, if you can. This lets the medicine reach deep into your lungs.  
  • For inhaled quick-relief medicine (beta-agonists), wait about one minute between puffs. There is no need to wait between puffs for other medicines.  
  • Rinse your mouth afterward, to help reduce unwanted side effects.


Look at the hole where the medicine sprays out from your inhaler. If you see powder in or around the hole, clean the inhaler. Remove the metal canister from the L-shaped plastic mouthpiece. Rinse only the mouthpiece and cap in warm water. Let them dry overnight. In the morning, put the canister back inside. Put the cap on.


For control medicines you take each day, write the date you need to replace it on the canister.

For example, say your new canister has 200 puffs (number of puffs is listed on canister) and you are told to take 8 puffs per day. This canister will last 25 days. If you started using this inhaler on May 1, replace it on or before May 25. Write the date on your canister.

Do NOT put your canister in water to see if it is empty. This does not work.


Young children may not be able to control their breathing enough to use a metered dose inhaler. A spacer can help. It is a chamber with a mouth piece that attaches to the inhaler. Once the medication is released, the spacer holds it until the child takes a breathe and inhales it. Other alternatives are to give the medication by mouth if it comes that way or to give it by a nebulizer.


Store your metered dose inhaler at room temperature. It may not work well if it is too cold. The contents of the canister are under pressure. So, do not get it too hot or puncture it.

Clean your inhaler the way the package insert tells you to.

Johns Hopkins patient information

Last revised: December 4, 2012
by Amalia K. Gagarina, M.S., R.D.

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