How can I tell if my inhaler is empty?

Some inhalers have a dose counter – this tells you how many puffs or sucks are left in your inhaler before it runs out. If it reads zero it tells you there is no medicine left and you should get a new one. But some puffer inhalers (called metered dose inhalers) don’t have dose counters, so how can you tell if your inhaler is empty? A help document by 


It’s a lot harder than you think!

How can I tell if my inhaler is empty?You may think that you can tell by shaking it or seeing if a spray comes out, but this doesn’t work. Even an empty inhaler will still ‘puff’ when you spray it or sound like it has something in when you shake it. This is because inside these inhalers, as well as the medicine to help your asthma stay well, there is also something called a propellant. This is what the inhaler uses to make sure the medicine sprays out far enough to reach your lungs. After the medicine has run out, there will still be propellant left, so you will still feel like you are spraying medicine. But you’re not - all you are spraying is propellant. Lots of people use empty inhalers without realising it. This can mean they are not getting their medicine when they need it and not getting the help they need to look after their asthma.

So what should I do?

If your inhaler without a dose counter is a preventer (you use it every day to keep your asthma well) the best thing to do is to work out when the inhaler is likely to run out and make sure you order a new prescription to arrive before then. To do this follow these steps:

  1. Check how many puffs (or ‘actuations’) the inhaler has when it’s new. This should be printed on the box, or you can check with your pharmacist. It is usually 120 or 200.
  2. Add up how many puffs you take per day altogether. This is usually 2 or 4 puffs daily.
  3. Divide the number of puffs in the inhaler by the number of puffs you take per day. So if your inhaler has 200 puffs in it and you use 4 doses a day, your inhaler will last 50 days (200 ÷ 4 = 50). You might want to mark this on your calendar or set a reminder on your phone a week or two before your inhaler is due to run out.

You can also use this table to help you work out how long your regular inhaler will last:


1 puff in the morning and 1 puff at night

2 puffs in the morning and 2 puffs at night

120 dose inhaler

Your inhaler will last 8 weeks

Your inhaler will last 4 weeks

200 dose inhaler

Your inhaler will last  14 weeks

Your inhaler will last  7 weeks


If your inhaler without a dose counter is a reliever (blue) inhaler, you probably won’t take this regularly, which can make it hard to tell if it has run out. The best way to know is to keep a written tally of how many puffs you’ve taken. Some people find recording it on a mobile phone can be helpful. 

Some people have more than 1 blue inhaler because they need them in different places, for example, one at home and one at school. Remember to keep different tallies for each inhaler. Try to avoid stockpiling lots of inhalers as this can make it even harder to track when they’re running out.

It is also possible to buy an electronic counter that attach onto some types of inhalers, but these are not widely available.


Will my inhaler go out of date?

If your asthma is well controlled, you will probably only need to use your blue inhaler once a week or less. This means it should last a few years, and it’s likely to pass its expiry date before it runs out so remember to check that too! If you need to use your inhaler more than twice a week then talk to your doctor or nurse about ways to get your asthma under better control. 

Are there any other options?

There is another type of inhaler called a dry powder inhaler and this type always comes with a dose counter. Most people aged 12 or over can use these inhalers well. These inhalers don’t need a spacer and are also better for the environment than metered dose (puffer) inhalers. Talk to your doctor or nurse if you’d like to try one of these inhalers. If you do change inhalers, make sure you get them to check you are using it properly and that your asthma stays well controlled.  


When you’ve finished using your inhaler take it back to your pharmacist. Metered dose (spray) inhalers contain powerful greenhouse gases, even when they’re empty. Your pharmacist can make sure they are disposed of properly.

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