Metered dose inhalers are also called MDIs or aerosol inhalers.
- The medicine is in a small canister, inside a plastic case.
- When the inhaler is pressed, a measured dose of medicine comes through the mouthpiece.
- Exactly the same dose is released each time.
- MDIs require good technique and coordination by pressing down on the inhaler and breathing in at the same time.
- Because using the inhaler correctly can be difficult, spacer devices are recommended for use with MDIs. The spacer is attached to the MDI to make it easier to use the inhaler and get more medicine into your lungs. See the image below.
- MDIs contain different medicines including preventers, relievers, symptom controllers and combinations of medications. Read more about asthma medicines in adults, asthma medicines in children and medications for COPD.
To get the most benefit from your inhaler, it's important to use the correct technique. Ask your healthcare provider to show you how to use an MDI device.
An MDI is the name of the device used to deliver the medicine to your lungs and airways. There are different names for each MDI depending on the medicines inside the device.
- It's important to know the name and colour of your MDI, eg, Ventolin®, Flixotide®, Serevent® or Respigen®.
- Your MDI may be a different colour to the one in the videos below. Read more about understanding your medicines(external link).
Using a spacer
A spacer is an attachment to use with your MDI. Using a spacer with your MDI makes it easier to use the inhaler and helps to get the medicine into your lungs, where it’s needed (with less medicine ending up in your mouth and throat). Spacers improve how well your medicine works. Children over 10 years of age may be able to use an MDI without a spacer; however, babies and young children must use MDIs with a spacer or a spacer and a mask. Read more about spacers.
Image credit: Healthify He Puna Waiora
Video: How to use your spacer device
The video below provides some guidance on how to use an MDI with a spacer.
(Healthify He Puna Waiora, NZ and Auckland District Health Board, 2018)
Video: MDI and spacer
(Asthma Waikato, NZ, 2018)
Common mistakes when using an MDI
- Breathing in too fast.
- Breathing out so hard that you cough.
- Pressing the puffer too early before you have started to breathe in (if you see a mist of medicine from your mouth, then you're making this mistake).
- Tilting your head down – it should be tilting back slightly.
- Pressing the inhaler twice during a single inhalation.
- Giving the inhaler a 'test puff' into the air and wasting the medicine.
- Breathing in through your nose instead of your mouth.
If you think you might be doing any of these things, ask your healthcare provider to watch you using your inhaler to make sure you're using the right technique.
Cleaning your MDI
Clean your inhaler every week to ensure it doesn't get blocked. It's best to follow the cleaning instructions that come with your inhaler, but here is some general guidance.
- To clean the inhaler, remove the mouthpiece cap and metal canister from the plastic casing.
- Rinse the plastic part under warm running water for at least 30 seconds.
- Shake off the water, and let it air-dry.
- Once dry, put the metal canister back into the plastic part.
- Test your inhaler by releasing one puff, then replace the cap.
Image credit: Healthify He Puna Waiora
Storing your MDI
- Always keep the cap on your inhaler when it's not in use.
- Store spare inhalers in cool places (not in your car glove box).
- Carry a spare clean plastic case so you can change it if the one you're using becomes blocked.
When to start a new MDI
- By shaking the inhaler it's possible to hear if there's any medicine left in the canister.
- Always have a spare inhaler ready, start this before the old one is completely empty.
- It may help to write the start date on the inhaler, so you can work out how long it will last with daily use. There are usually 200 puffs per canister.