Skip to Accessibility Tools Skip to Content Skip to Footer
inhaler wearing floaties in water

Inhaler Float Test?!

I was on a call with a group of nurses, and we were talking about the details of a new Stock Inhaler Law our state recently passed.

Some of you may be wondering, “What is a Stock Inhaler Law?” Well, some states in the U.S. have passed a law that lets schools keep an emergency asthma inhaler in the front office. (If you are wondering if your state has passed that law, you can look at the map from Allergy & Asthma Network.)1

Having a backup inhaler for students

If a student forgets their inhaler, or they find out their inhaler is empty, they can use the emergency inhaler in the office. But first, they have to be diagnosed with asthma, and have an Asthma Action Plan on file. So, great idea, right? A student can have a puff or two of a rescue inhaler and go back to class.

So as we were talking about the details, some of the nurses were wondering if it would be better to have an emergency asthma inhaler or a nebulizer in the office? One of the nurses complained that it’s hard to have an inhaler, because you have to use the “inhaler float test” to see how many puffs are left in the inhaler.

Up to that point, I had just been listening to the conversation – but as a Certified Asthma Educator (AE-C), I HAD to speak up during the phone call. Ethically, part of my job is to correct any misinformation. Nurses are amazing! But they can’t be experts in every area, so I had to update them when it came to asthma.

The inhaler float test is not recommended

The float test is no longer recommended for inhalers. In fact, information from as far back as 2002, said that:2

“Float characteristics are product-specific and a function of canister size, design, content, and method of testing. Clinicians and asthma educators should not advise patients to use a float test to assess the amount of medication remaining in an MDI.”

Basically, they found that the “inhaler float test” is not accurate. (And by the way, MDI stands for metered-dose inhaler.)

Another article shows that:3

“Some people also believe that an empty inhaler will float, but this is not a reliable test. You can get different results depending on whether the stem of the inhaler is up or down in the water. Also, some inhalers will float when they are full.”

Monitoring medicine without the inhaler float test

So, how do you know if the inhaler has any medicine left in it? Well, most of the inhalers have counters on them now. Some are on the top of the canister, some are on the back. The trick is to make sure that you remember to look at the counter on your inhaler.

I am so caught up with work, college kids, car problems, etc, that sometimes I forget to look at the counter. In fact, you can read more about when I went on a work trip with an empty inhaler here. It was definitely a “facepalm” moment…

You might ask, “Well, can’t you tell when your inhaler is empty by how it feels?” The problem is that the inhaler may still have propellant, but no medicine. So you may take a puff and feel a “spray” come out of the inhaler. However, once it’s empty you will only get a puff of air, not a puff of medicine.

Make sure you use proper inhaler technique

For our schools, we are going to price check options and see which would be better to have in our schools – inhalers or nebulizers. But I will train the nurses to make sure they know proper inhaler technique. And I will make sure they just look at the counter on the inhaler (instead of using “float test.”)

I wish I could give all of our school nurses some chocolate and a gift certificate for a massage. But all I can give them is a little updated asthma education!

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

  1. Allergy & Asthma Network. School stock albuterol and asthma management. Accessed 10/23/2019.
  2. Brock TP, Wessell AM, Williams DM, Donohue JF. Accuracy of float testing for metered-dose inhaler canisters. Journal of the American Pharmaceutical Association. 2002;42(4) doi: DOI: 10.1331/108658002763029553
  3. Is your inhaler running on empty? Accessed 10/23/2019.


  • Shellzoo
    2 months ago

    Nice article. I am a RN and never heard of an inhaler float test. Where I work the RTs do all the inhaler and neb treatments. My job is to access and call if I feel a treatment is necessary. If I have an order, I call the RT, if I need an order the physician then RT. We nurses can certainly use more asthma education as many of our patients have asthma as an underlying condition and the possibility of a flare-up. Thanks for all that you do. I know this site has certainly helped me both as a patient and nurse.

  • Andrea M Jensen, CHES (R), AE-C author
    2 months ago

    Aw thanks Shellazoo! I try to share unique, new ideas for people with asthma.

    I know you deal with acute care, but I specialize in helping people once they are at home. This is one of the old school “tricks” that patients used to do before they added counters to inhalers.

    Keep up the good work in taking care of your patients! 🙂

  • John Bottrell, RRT moderator
    2 months ago

    Great article, Andrea. I think I would have given the same tip to the nurses. It certainly is nice having the counter on inhalers today. I do think there is viable evidence suggesting that inhalers work better for kids than nebulizers, so long as they are used with spacers. Some hospitals are switching to only inhalers for kids in emergency rooms. So, interesting subject. All the best. John. Site Moderator.

  • Andrea M Jensen, CHES (R), AE-C author
    2 months ago

    I have seen that study, but disagree!

    I don’t think they considered whether people have mild, moderate or severe asthma.

    As we know, there are so many phenotypes and endotypes, that’s it doesn’t seem right for researchers to make blanket statements that inhalers are just as effective as nebulizers.

    I know that when I (or my kids) get pneumonia or Influenza A, we are so tight that we can’t even breath in well enough to use our inhalers.

    Only a nebulizer will do!

    Same thing happens with a sudden severe asthma attack – where I’m coughing so hard I’m trying not to throw up.

    I can’t breathe in to use an inhaler when I am coughing that hard – I’ll just cough the medicine right back out!

    We always keep inhalers and nebulizers handy – depending on how sick we are!

  • Andrea M Jensen, CHES (R), AE-C author
    2 months ago

    I’m so glad. Thanks to that study, my in state hospital system is adamant that only inhalers are needed. I strongly disagree, so it’s good to see they are using more nebulizers.

    One doctor once said, “It’s not like you can take your nebulizer on vacation.” Wanna bet? Our nebulizer has been to the Grand Canyon, Disneyland, grandma’s house, etc etc.

    Sometime only a nebulizer will do!

  • Shellzoo
    2 months ago

    In the past I have seen rescue inhalers ordered as needed but as of late the as needed orders are for nebulizer treatments so, the trend I am seeing is nebulizer treatments over inhalers.

  • Poll