How Long Your Inhaler Will Last

When Inhalers Run Out and When They Expire

When you have asthma, it's important to know how long your inhaler medications will last and to be able to gauge when you are running out. While some inhalers have a counter to help you keep track, others don't, leaving it up to you to calculate how much more use you can get out of them. This can be particularly challenging for rescue inhalers, which are used sporadically and only as needed.

You'll know when a preloaded inhaler is empty; these inhalers typically contain from 50 to 200 doses of medication and will eventually just run out, at which point you obviously should get a refill.

But metered-dose inhalers (MDIs or HFCs) contain a chemical that will continue to spray even after the medication is used up, meaning you may be using it without actually getting treated if you haven't been tracking your doses.

How you store your inhaler and when it expires also factor into how long your inhaler will last you.

South Africa, Cape Town, young jogger using asthma inhaler on the beach

Westend61 / Getty Images

Types of Inhalers

Maintenance inhalers, also called controllers, are used regularly to prevent asthma symptoms.

Rescue inhalers are what the name suggests—they contain medication to be taken to quell symptoms or assuage a sudden asthma attack. Whether or not your inhaler has a counter to track doses depends on the specific medication you are prescribed, not which of these types of inhalers you are using.

Inhalers With a Counter

Inhalers with a counter will keep track of the amount of medication remaining in the device.

The Flovent HFA inhaler, for example, has a counter that shows how many sprays of medicine are left in the device. The counter starts at 124 and counts down by one each time you spray the inhaler. The counter will stop counting at 000, at which point the manufacturer recommends that you don't use it anymore.

Another controller, Qvar (beclomethasone dipropionate HFA) comes as an MDI with 120 inhalations per canister. It has a counter that reads zero when the expiration date is reached or when the product is used up, whichever comes first.

Inhalers Without a Counter

If your inhaler does not have a counter, the number of puffs in each canister should be printed on the inhaler's label.

Controller Inhalers

You can calculate the number of days of use you will get out of a controller inhaler by dividing the total number of doses in the canister by how many doses you are told to use per day. Then you can use a calendar to figure out the date when your medication will run out.

Note that for some people with mild to moderate persistent asthma who use a controller inhaler daily, less frequent use may be possible, according to updated recommendations for asthma management by the National Institutes of Health (NIH) issued in December 2020. If you use an inhaler daily to manage asthma, talk to your healthcare provider about how the new guidelines might affect your treatment.

Don't hesitate to ask for help. When you aren't familiar with a specific package, the labeling isn't always obvious. Once you calculate the number of doses and the day when you expect to run out of medication, it is a good idea to double-check your calculation with your pharmacist.

To keep track of this information, write the start and end dates of the medication on your canister as soon as you pick it up from the pharmacy. Schedule your next refill pick-up in advance to avoiding lapses in treatment.

Rescue Inhalers

Determining when a rescue inhaler will run out is more challenging than keeping track of a controller since you won't use the same dose of rescue medication regularly.

It's impossible to predict how many doses of a rescue inhaler you will need. And it is not realistic to expect yourself to remember how many you have used.

Albuterol, a bronchodilator that widens the airways, is a commonly used rescue inhaler. It is supplied in an 8.5-gram canister containing 200 puffs of medication.

The manufacturer of albuterol warns against using methods or "tricks" to try to figure out how much medication is left in the canister with a notice to never immerse the canister in water to determine how full the canister is (the so-called “float test”).

The best way to keep track is to maintain a log of how often you are using your rescue inhaler. Aside from helping you determine when you'll need a refill, this will also help in assessing how well your controllers are working. If you are using a rescue inhaler on a daily basis, your healthcare provider might make changes to your controller medication to reduce the frequency of your asthma symptoms.


Having a full inhaler is important, of course, but if that medication has expired, there's a chance the drug might not have retained its strength, quality, and purity. Paying attention to the expiration date of your inhaler, therefore, is just as important a consideration of how long it will last.

Expiration can be a major concern for any medication, but it's especially important with rescue inhalers, which may be used only rarely for asthma that's well controlled. While you may feel secure knowing you have an inhaler handy, that inhaler may not prove effective once you go to use it if it's past its expiration date.

If you use albuterol, for example, make sure you are scheduled to get a refill before your inhaler expires, even if you hardly ever need to use it. You don't want to be caught without a safe and effective rescue inhaler when you suddenly need one.

According to the Food and Drug Administration (FDA), the date of a drug's expiration is based on its chemical stability.

With Qvar, the counter will read 0 when the expiration date arrives. Other inhalers will have an expiration date on the box and the inhaler itself; by law, all drugs have to be labeled with an expiration date.

Keep in mind that expiration dates are only valid for inhalers that are stored according to the manufacturer's instructions. Medications can become unstable—and therefore ineffective or unsafe—if they are not stored properly.

Storage and Disposal

Most medications, including inhalers, need to be kept at optimal temperatures. While you might want to keep your inhaler in your car for convenience, for example, keep in mind that hot or cold temperatures can compromise your medication.

Humidity, such as in a bathroom, can alter the chemical composition of medications used in an inhaler as well. Humidity can also get your device slightly wet, interfering with the dose that is delivered with each inhalation.

Each inhaler will have specified temperatures and storage recommendations, so be sure to read the labels or ask your pharmacist for advice.

For example:

  • According to the manufacturer, albuterol should be stored at temperatures between 59 and 77 degrees F. The container may burst at very high temperatures.
  • Symbicort should be stored at a room temperature of 68 to 77 degrees F with the inhaler mouthpiece down.

When you are done with an inhaler or it has expired, it is best not to throw it in the trash. As medication may be left inside it, there is a chance it could explode if exposed to high temperatures (say, in a garbage truck). Medication and propellants could also leak out into the environment.

Instead, speak to your pharmacist to see if they can dispose of your inhaler. Some pharmacies have drop-off boxes for drug disposal, and others may hold special take-back days or events. Your local health department or police/fire station may do the same from time to time.

A Word From Verywell

Asthma inhalers directly reach the lungs to have a therapeutic effect. They can be convenient to use, but it isn't easy to see how much medicine you have left. Once you get into a routine in terms of replacing, storing, and caring for your inhaler, you will feel more comfortable with the whole process.

Keep in mind that your inhalers might not all last the same length of time, and each may have its own storage specifications and expiration dates.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Flovent HFA label.

  2. Food and Drug Administration. Qvar label.

  3. American Academy of Family Physicians. How to use a metered dose inhaler.

  4. Cloutier MM, Baptist AP, Blake KV, et al. 2020 focused updates to the asthma management guidelines: A report from the national asthma education and prevention program coordinating committee expert panel working group. Journal of Allergy and Clinical Immunology. 2020;146(6):1217-1270. doi:10.1016/j.jaci.2020.10.003

  5. Food and Drug Administration. Proair HFA (albuterol sulfate) label.

  6. Food and Drug Administration. Expiration dates—questions and answers.

  7. Food and Drug Administration. Symbicort label.

By Pat Bass, MD
Dr. Bass is a board-certified internist, pediatrician, and a Fellow of the American Academy of Pediatrics and the American College of Physicians.