If you’ve ever pulled a dusty old bottle of mouthwash from under the sink, you may have wondered if it was still safe to use. Can mouthwash expire? Well, the answer is yes, and there are good reasons not to gargle the bottle’s contents after the mouthwash expiration date.

Using expired mouthwash can be risky for a number of reasons and likely won’t be an effective use of your time, even if it is still safe to use. Today, we’re going to look at how long you can expect your bottle to last, some additional tell-tale signs that it has gone bad, and whether or not it’s safe to use expired mouthwash. We’ll begin by examining the age of the bottle.

How long does mouthwash last?

As a general rule of thumb, you can expect most unopened brands of mouthwash to last 2-3 years from the date of manufacture. Since it may have been sitting in a warehouse or on the store shelf for some time, you may expect to get two years of service out of it from the date of purchase. This isn’t a failsafe plan, however.

The way you store your mouthwash can also have an effect on its lifespan. Once opened, mouthwash expiration is expedited and can begin to turn in as little as six months to a year. Keep the bottle tightly sealed, keep it away from sunlight, and try to use it within a year after it has been opened.

Keep in mind, also, that not all mouthwash formulations can be expected to last a full two to three years. Some formulas are intended to strengthen teeth and prevent tooth decay, while others may be intended for teeth whitening or to improve breath by restricting bacterial growth. The unique formulation of each variant can result in faster or slower decay times, so you should always check the bottle for a mouthwash expiration date. Even better, check the manufacturer’s website for more complete information.

What can happen if you use mouthwash past its expiration date?

The breakdown of active ingredients that are prone to decay over time can not only make your mouthwash less effective, but it can actually leave your bottle contaminated with bacteria or rancid ingredients. Let’s look at both scenarios, as well as why they should be enough to dissuade the use of expired mouthwash.

It will be ineffective

As mentioned, the active ingredients in mouthwash will decay over time, leading them to be ineffective as a mouth rinse. In fact, according to the FDA, as well as most manufacturers, there is no therapeutic value in a bottle of expired mouthwash. That said, there’s little incentive to use it after it has passed the mouthwash expiration date. Best case scenario, you’ve wasted your time.

It can introduce bacteria

More seriously, if the active ingredients have expired, there’s a chance that harmful bacteria could be growing in the bottle. Not only does this make it ineffective as an oral rinse, since the active ingredients are no longer able to kill bacteria, but a contaminated bottle can negatively affect your health.

In a December 2020 recall of a mouthwash product that was found to be potentially contaminated with a bacteria called Burkholderia lata, which the FDA said could potentially result in oral and, potentially, systemic infections requiring antibacterial therapy. Exposure by the most at-risk populations could have put them at risk for life-threatening infections such as pneumonia and bacteremia.

This is too much risk to take on a bottle that has passed the mouthwash expiration date, especially since a new one can typically be had for less than ten dollars. Even if the mouthwash still looks safe to use, if the date has passed, it’s best to throw it out.

Additional indications your mouthwash has turned

Even if the date hasn’t passed, but something looks off, it’s a good indication that you shouldn’t use it. You may notice a change in the taste, color or texture. Any one of these scenarios could mean the wash has gone bad prematurely and that it may contain bacteria or rancid ingredients. If in doubt, throw it out.

Bottles without a mouthwash expiration date

Sometimes we encounter bottles without an expiration listed on them at all. If you’ve had it a long time, it’s best to simply toss it and pick up a new bottle. Again, there’s no rationale for exposing yourself to potential harm when you can mitigate it by dropping a few dollars on a new bottle. 

If the new bottle you just bought is missing an expiration date, take note of the date you purchased it. The mouthwash inside will likely be good for a couple of years, so you can create your own mouthwash expiration date to remind you how long you have to use it up.

You can also look for a date of manufacture. Even in the absence of an expiration date, if you have a manufacture date, you’re typically safe using it within whatever time frame is outlined by the manufacturer.

Using expired mouthwash

Just because the mouthwash expiration has passed, that doesn’t mean you can’t still use it in some capacity. If you’re averse to wasting your hard earned money, there are some great ways to repurpose expired mouthwash that are perfectly safe.

Cleaning windows and mirrors

An alcohol-based mouthwash can actually perform surprisingly well as a glass cleaner. It’s got enough power to remove dirt and debris from smooth surfaces and the alcohol will evaporate away, leaving a streak-free shine.

In the garden

Mixing up a concoction of three parts water to one part mouthwash can prevent mildew and fungus, as well as repel insects when sprayed weekly on garden plants. This can effectively eliminate some of the most common pests in a plant’s world. 

If bugs are still causing problems, you can up the concentration. Mixing two parts water to one part mouthwash will increase its effectiveness as a bug repellent.

Cut flowers can benefit too

Adding a tablespoon of mouthwash to four pints of water can make your cut flowers last longer when used in place of regular water in the vase. It accomplishes this by helping to kill bacteria that cause cut flowers to sag or droop.

Add it to your laundry

Adding a cup to your wash cycle can leave your laundry smelling fresh and clean. Even if it's past its mouthwash expiration date, the alcohol in the bottle should be enough to help kill bacteria and mildew that commonly winds up on wet laundry such as towels and gym clothes. 

The takeaway

Using mouth rinse products past their expiration can, at best, be a waste of time. On the other hand, it can introduce bacteria to your mouth that have the potential to cause real harm. If you’ve got a bottle that’s past the mouthwash expiration date, throw it out or repurpose it. Your body will thank you.