


How to Use a Metered-Dose Inhaler the Right Way

Using a metered-dose inhaler is a good way to take asthma medicines. There are few side effects because the medicine goes right to the airways inside the lungs. A spacer or valved-holding chamber attached to the inhaler can help make your inhaler easier to use and more effective. For patients taking inhaled steroids, a valved-holding chamber or spacer may help prevent irritation to the mouth.

See a video that shows how to use an MDI the right way.

Diagram of Metered Dose Inhaler

Steps for Using an Inhaler


Priming is needed to make sure the dosing chamber of the MDI fills with the right amount of medication when you are ready to use it. You will need to prime the MDI the first time you use a new MDI and again if you have not used your inhaler for several days or weeks. To prime your MDI:
  • remove the cap of the MDI
  • shake the inhaler
  • spray it in the air away from you
The number of sprays needed to prime your MDI will depend on the type of medication. The instructions that come with your inhaler tell you when and how many times the MDI must be primed. Read the instruction for each inhaler carefully because each inhaler you have may have different priming instructions. If you have trouble reading the instructions, ask your pharmacist for help.

Get ready

  1. Take off the cap and shake the inhaler.
  2. Breathe out all the way.
  3. Hold the inhaler in one of these two ways, as your doctor or asthma educator said:
  • Use a spacer/valved-holding chamber (the best way, useful for all patients) by putting the inhaler into the end with the hole and the mouthpiece end in your mouth.

person holding valved-holding chamber

  • If you don't have a spacer, hold inhaler 1 to 2 inches (or two finger widths) in front of your open mouth

person using metered dose inhaler without a spacer

Breathe in slowly

  1. As you start breathing in slowly through your mouth, press down on the inhaler one time. If you are using a spacer or valved-holding chamber, press down on the inhaler before starting to breathe in. Breathe in slowly.

person using valved-holding chamber

  1. Keep on breathing in slowly, as deeply as you can.

Hold your breath

  1. Hold your breath as you count to 10 slowly, if you can.

Dry Powder Inhalers

Dry powder inhalers are used differently. To use a dry powder inhaler, close your mouth tightly around the mouthpiece and inhale very fast. View more information on how to use dry powder inhaler.


The inhaler should be cleaned often to prevent buildup that will clog the inhaler.
  • Once a day, clean the inhaler and cap by rinsing them in warm running water. Let them dry before you use it again.
  • Twice a week wash the plastic mouthpiece with mild dishwashing soap and warm water. Rinse and dry it well before putting it back.

Knowing When To Replace Your Inhaler

Some inhalers now include counters so you always know how many puffs are remaining in the device. For those that do not have counters, there are a variety of methods to determine how many puffs (i.e., how much medicine) is left.

If the canister is new, it is full. The number of puffs a canister contains is listed on the label. Do NOT put your canister in water to see if it is empty. This does not work.

  • For a medicine you take each day: Take the number of puffs in the canister when it is full, and divide it by the number of puffs you take every day. This will tell you how many days your inhaler will last. For example:

Your inhaler canister has 200 puffs in it, you are told to take 8 puffs total every day.

200 puffs in container / 8 puffs per day = 25 days

This canister of medicine will last 25 days, so if you started using it on January 1, you should replace it on or before January 25.