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, which means it's 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 only used as needed.

You'll know when a preloaded inhaler is empty; these inhalers typically contain 50 to 200 doses of medication and will eventually just run out. Though it's obviously better not to wait until this happens to 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.

Number of Uses

Maintenance inhalers, also referred to as controllers, are the inhalers you take every day to prevent asthma symptoms. Rescue inhalers are the inhalers you need to take when you experience symptoms or a sudden asthma attack.

Whether or not your inhaler has a counter to help you track your 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 you have left.

The Flovent HFA inhaler, for example, has a counter that shows how many sprays of medicine you have remaining. 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

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

Symbicort is a controller that contains budesonide (a steroid) and formoterol fumarate dihydrate (a long-acting bronchodilator). This medication comes in canisters containing 60 or 120 doses each.

Don't hesitate to ask for help. When you aren't familiar with a specific package, the labeling isn't always obvious. And 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.

Be sure to keep track of this information by writing the start and end dates of the medication on your canister right when you pick it up. And schedule your next refill pick-up in advance so you won't skip any treatments.

Rescue Inhalers

Keeping track of when your rescue inhaler will run out is more challenging than keeping track of controllers because you won't use the same dose of rescue medication every single day.

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”).

You can keep 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 doctor might make changes to your controller medication to reduce the frequency of your asthma symptoms.

Expiration

Having a full inhaler is important, of course, but if that medication has expired, there is a chance that 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 you might only use rarely if your asthma is well controlled. While you may feel secure knowing that 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 U.S. 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 if your inhaler is 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 the medications used in your 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 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 on-hand all the time; others may hold special take-back days or events. Your local high 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.

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Article Sources
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  1. Food and Drug Administration. Flovent HFA label. Updated November 2010.

  2. Food and Drug Administration. Qvar label. Updated September 2017.

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

  4. Food and Drug Administration. Symbicort label. Updated January 2017.

  5. Food and Drug Administration. Proair HFA (albuterol sulfate) label. Updated February 2019.

  6. Food and Drug Administration. Expiration dates—questions and answers. Updated April 26, 2018.