What happens if you use expired mouthwash?

Almost every product has a shelf life. And as you can guess, using any expired product is by no means a good idea. This of course also applies to dental products. It may be time to say goodbye to the mouthwash bottle that has been a long-time guest in the corner of your bathroom. Why are we saying this? Well, because if you keep using your expired one, you might end up with some trouble. So, what exactly do we mean by trouble? What happens if you use expired mouthwash? Let’s clear things up for you.

What happens if I use expired mouthwash?

First of all, most mouthwashes have an expiration date of 2-3 years. It is usually written on the bottles. Expiration date unknown? And now you’re wondering what happens if I use expired mouthwash.

Most mouthwashes consist of active ingredients such as alcohol, water, and antiseptic components. And these substances become less effective in protecting your mouth over time. They can also cause a chemical reaction if you don’t store them as recommended. In this case,  instead of reducing the harmful bacteria in your mouth, they can increase them even more. In short, these stale substances will trigger bacterial growth. As a result, it can lead to some oral health problems.

You should also use alcohol-free mouthwashes until a certain date. Expiration dates may vary from type to type though. But, just like most types, their ideal usage is 2-3 years. They may even have shorter expiry dates than alcohol-based ones because alcohol kills bacteria. In other words, most mouthwashes that do not contain alcohol are easier to form bacteria. That’s why you shouldn’t be misled by the fact that it does not contain alcohol. 

What about antibacterial mouthwashes that contain fluoride? Well, one study about fluoride toothpaste says this substance loses its effectiveness over time. And, fluoride in oral products is essentially the same. It doesn’t matter if the products are different. So, if you have complaints such as increased tooth decay, there is no harm in checking the dates of your products. (1)

Take PAO as a hint

We talked about the dates on mouthwash bottles and what you can do for products that don’t have one. So, would you like to learn another method? We may not always consider checking the back of the oral health products we buy. But in fact, by doing so, you can get information about the products through some symbols used by international companies. For example, the period after opening symbol, a.k.a “PAO”, is one of them. It tells you how long your product will last after the bottle is opened. You can recognize this symbol by the number of months written on an open jar. Next to this number, the initial letter of the month “M” is written. So, if the total of the month you can use your product is 12 months, it will be written as “12M” on the picture of this jar. If you want to make this symbol even more useful, here’s a trick for you! You can combine this information with the post-it method. With this way, you now know the opening and the end date!

How safe/unsafe is it to use expired mouthwash?

There is no doubt that it’s not very safe to use any product that has expired. The same goes for mouthwashes. Although it is not recommended to use mouthwash after the expiration date, it’s also not “that” dangerous. You see, your teeth won’t be damaged or your gums won’t start bleeding immediately. You’ll be okay if you used it for some time after the expiry date and haven’t noticed an unusual consistency. It can depend on the type of mouthwash or the brand. Not all products have the same chemical formulations.

Let us remind you again, though. Ignoring these dates can have harmful effects on your oral health. If you are unsure of the date of the old one, now is the time to get a new bottle of mouthwash.

How long can you use mouthwash after the expiration date?

There’s no specific number of days you can keep using the product after the expiry date. Might be 2 days or 2 weeks, nobody can tell the exact time period. But, knowing that the expiry dates are determined by mouthwash stability tests during production can be a relief. As you can imagine, no one can risk incorrect expiry dates. Otherwise, consumers won’t be happy with the results and stop trusting companies… So, have no trouble trusting what is said on the bottle. However, if there’s a noticeable difference in any shape or form in the product, throw it away. In fact, it would be best for you to just get rid of it after expiration without waiting for any deformation. Nobody wants to put their health at risk, right?

Don’t want to waste the remaining product by throwing it away? We have good news for you! Your expired mouthwash is now a toilet bowl cleaner! Just pour some around the edges and let it sit for half an hour to an hour. After scrubbing a little, the magic happens. You won’t believe your eyes! It’ll look almost as if you have a new toilet. 

How to tell if mouthwash has expired

Most mouthwashes have active chemicals in their formulas. When a bottle goes bad, these chemicals usually deteriorate. So now your mouthwash product is just a chemical cocktail. If this happens, you may notice a strange smell, taste, or color in the product. Especially if you haven’t been paying attention to storing it as recommended. It can’t be good for your bottle to be “sunbathing”… It should be preserved in cool, dry, and dark places. You can put it in your medicine cabinet, for example, it’ll provide an ideal condition.  


1. MATIAS JB, AZEVEDO CS, VALE HF do, REBELO MAB, COHEN-CARNEIRO F. Fluoride stability in dentifrices stored in schools in a town of northern Brazil. Brazilian Oral Research. 2015;29(1). doi:https://doi.org/10.1590/1807-3107bor-2015.vol29.0121 Link