How Long Your Inhaler Will Last

Woman using inhaler at the beach

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It is important to know how long your inhaler medication will last so that you will not unexpectedly run out of medicine and end up with an asthma attack. Unfortunately, you cannot see inside the canister like a bottle of pills to know when your medication is going to run out. So how can one figure out how much medicine is left?

Many inhalers include a “counter” on the back that keeps track of how much medicine is left in the device. Flovent, for example, has a counter to show how many spray of medicine you have left. The counters starts at 124. The number will count down by 1 each time you spray the inhaler. The counter will stop counting at 000.

If your inhaler does not have a counter, the number of puffs in each canister should be printed on the inhaler's label. You will simply divide the total number of doses in the canister by the total number of doses taken per day. If your healthcare provider has prescribed 1 puff twice per day, your inhaler will last 60 days (120 divided by 2). Albuterol inhalers, a rescue bronchodilator, on the other hand, has 200 puffs per inhaler. If you use 2 puffs per day, your rescue inhaler would only last 100 days. If you are using your short-acting bronchodilator more than twice per week or if you need to get it refilled more than twice per year, discuss increasing your controller medication with your healthcare provider.

If you keep a separate daily log of how often you are using your controller and rescue inhaler, you will be able to tell after several days how long your inhaler will last. I usually recommend to my patients that they write a “dead” date on their controller inhaler when they pick it up from the pharmacy. The patients simply figure out how long the inhaler will last and write the date it is expected to run out on the inhaler so that they can pick one up from the pharmacy. I also advise patients to always have an extra rescue inhaler on hand.

Old and Expired Inhalers

How often do you perform spring cleaning in your medicine cabinet? Or you find an old asthma inhaler in the glove box while cleaning out your car, in the old key drawer in the kitchen, or sitting at the bottom of your sock drawer and notice that it seems to still be half full. Now you're thinking about the cost and wondering: Can I still use it? I really don't want to waste it, but is it safe? Will it still work when I need it to? Is it even okay to use expired asthma medicines? 

By law, all drugs must have an expiration date. Surprisingly, very little information is out there for consumers related to this in general and very little specifics related to asthma medications. Pharmaceutical companies do not really comment or provide guidance to physicians about the use of their products beyond the labeled expiration date. This is presumably because of legal restrictions and liability concerns, but one could also see that it is bad for business.

In 1986, the FDA established the Shelf Life Extension Program (SLEP). The program tests stockpiles of drugs to determine stability after the expiration date and has been estimated to save the military as much as $100 for every dollar invested by preventing the need to throw away drug just sitting on a shelf. This also has implications related to natural disasters and other emergencies. 

According to The Medical Letter, 88% of 122 different drugs stored in their unopened original containers remained stable more than 5 years after their expiration. Of the 18% that eventually failed, none failed before one year. While the article does not specifically mention asthma medications, heat or humidity (think your bathroom) is known to shorten the half-life of medications. Also realize that the drugs in SLEP were stored unopened, in favorable conditions—not your glove box or kitchen drawer. Unfortunately, once you pick up your medications home from the pharmacy and begin using them, they are no longer being stored under the controlled conditions used in the SLEP research.

Medications in a dry, cool, and dark environment may be less likely to break down. Further, solutions and suspensions are not going to remain stable as long as solids or powders—this has a direct implication for asthma. To address the shortage of EpiPens, on June 5, 2019, the FDA announced the extension of the expiration dates by four months of all lots of EpiPen 0.3 mg Auto-Injectors and its authorized generic version currently on the market in the U.S.

What does this mean for you? As a patient and consumer, you need to monitor and follow expiration dates very carefully. Once opened and exposed to the environment, there is no way to predict their effectiveness and there is no reliable data that allows for an evidence-based answer to the question "Can I use an expired inhaler?". If there is no suitable alternative available, expired drugs may be effective and there is no indication that they are not safe. I have had patients tell me that they used drugs years after and had no problems. I have also had patients tell me they were not effective.

You should not need to use controller medication after an expiry date since you are using them daily as part of your asthma action plan. If your asthma is well controlled you will not need or complete a rescue asthma inhaler in a year. I advise my patients to replace them yearly. SLEP indicates that most medicines will still be effective for at least a year after the expiration date. To guarantee your safety and that the asthma medicines work for you, I do not recommend using rescue inhalers too far after their expiration date. Your breathing depends on it.

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Article Sources

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  1. American Academy of Family Physicians. How to Use a Metered Dose Inhaler. Updated July 22, 2019.


  3. US Food & Drug Administration. Expiration Dating Extension

  4. Drugs Past Their Expiration Date. JAMA. 2016;315(5):510-1. doi:10.1001/jama.2016.0048

  5. EpiPen Prescribing Information. Supply Status Update. June 2019

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