Is Expired Mouthwash Safe To Use?

You’ve been going through cupboards while trapped in quarantine and have found a bottle of mouthwash that you don’t even remember buying. It looks and smells OK, however, you have no idea of the manufacturing date and the “use by” date is long past. Can you use it, or should you dump it out and recycle the bottle?

Is expired mouthwash unsafe, or just useless? First of all, there’s no sense in using it if it’s no longer effective. Users should also be aware that mouthwash that contains alcohol for disinfecting purposes contains other chemicals that actually protect your teeth. The disinfecting alcohol can act on the tooth-protecting chemicals, rendering them useless. Worse, the disinfecting agents in the bottle can fail, causing bacterial growth.

Can Mouthwash Actually Expire?

Yes. Each mouthwash has its own formula for killing bacteria, freshening your breath, and boosting your dental health. This balance of formulas is actually quite delicate, so if something in the bottle ages out of its usefulness, the mouthwash can’t do what it was formulated to do. Sometimes, one chemical in the cocktail will wipe out the other products and move up the concentration ladder.

While mouthwash is mostly water, the chemical formulation is designed to both strengthen your teeth and protect your mouth from bacteria. If the formula is altered because the product is old, you don’t want to put an out of balance formula in your mouth.

What Do Expiration Dates Really Mean?

The expiration or use by date on your bottle of mouthwash pertains to the antiseptic. Many user of mouthwash use the little cup at the top of the bottle. If this is your habit, you’ve transferred mouth bacteria to the cup. If you then rinse the cup and put it back on the bottle, you’ve added tap water to the bottle.

Should you then put the bottle back in the cupboard and forget about it, remember that the bottle now contains

  • bacterial remnants from your mouth, or possibly live bacteria, and
  • tap water, plus
  • the original, possibly degraded mouthwash.

Your best bet is to not open the bottle and just toss it.

Read: Does Dental Floss Expire? Why It Might Matter

What Would Happen To You If You Used Expired Mouthwash?

Quite possibly, nothing. It may not cause you any damage at all. However, it’s unlikely to do you any good. While it would be nice to think that mouthwash formulations could last forever, it’s important to remember that these products are designed to be used to protect some fairly delicate tissue. Few liquid suspensions last forever, and those that do are not exactly therapeutic.

Mouthwash is designed to wipe out bacteria while not damaging your gum tissue or tooth enamel. Any chemical mixture that is diluted enough to do this successfully needs to be inherently mild. It may have a powerful flavor, but our taste buds, tongue, cheek linings and gums are actually quite fragile. Killing bacteria while not burning that fragile tissue takes a particular formulation, and this formulation breaks down over time.

Additionally, mouthwash needs to police itself to reduce the risk of bacterial contamination from backwash. Left sealed for too long, the antibacterial products in the mouthwash can wipe out the good qualities in the liquid and render it useless.

In Conclusion

Old mouthwash is not a bargain and you’re not breaking any rules of frugality if you get rid of it. In fact, expecting it to do you good when the formulation has changed so much that it’s useless can actually cause more problems than dumping it out.

You may expect protection where it no longer exists and make poor dental choices. If you can’t use up a bottle before the expiration date, purchase travel sized products.

More helpful dental articles

Recent Posts

Legal Disclaimer is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Additionally, also participates in other affiliate and advertising programs, such as AdSense, ShareASale, Awin, Etsy, and CJ among others, and is compensated for referring traffic and business to them.