Yes. Each mouthwash, like Listerine, TheraBreath, ACT, CloSYS, Colgate, Crest 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.

Mouthwash expires just like every other medicine, beverage and food. This liquid can only sit on your bathroom counter for so long before it either goes bad or no longer proves effective for mouth cleaning. If your mouthwash has expired, do not use it.

Everything You Need to Know About Using Mouthwash

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.

How Long can Mouthwash be Used?

In general, mouthwash can last for a couple years beyond the manufacture date.  At a maximum, mouthwash will last three years following the manufacture date. The majority of mouthwash has alcohol or another form of antiseptic.  While alcohol is an active ingredient, most types of mouthwash have a considerable amount of water. The antiseptic will begin to dissolve, after two to three years. The dissolving antiseptic will leave the mouthwash with that much more water and boost the chances of bacterial growth.

Throw out Old Mouthwash

There is no sense using a mouthwash that passes the expiration date.  If your mouthwash reaches the expiration date or is at least two years beyond the manufacture date, trash it.  Even if the expiration date has not been reached and the texture changes, you need to throw it away. Furthermore, if the mouthwash does not look normal, do not hesitate to throw it away.

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 listerine mouthwash can wipe out the good qualities in the liquid and render it useless.

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.

How long does a bottle of mouthwash last?

The general rule of thumb is that mouthwash lasts two years from date of manufacture. Some may last longer, depending on their ingredients (we discuss this below). All Listerine products are safe for use up to 12 months after opening.

If a mouthwash has an expiration date this is a good sign. It tells you the manufacturer has invested time and money in testing to find out how long it will remain safe and effective for.

A mouthwash without an expiration date is not a sign that it won’t expire. It’s a sign that the makers haven’t tested how long the ingredients remain effective for before they degrade! Use a permanent marker to write the date of purchase on the bottle and keep an eye on the contents. Check for signs of color or texture change which show the mix is breaking down.

Where an expiration date is displayed, you should observe it and throw away the product when that date is reached.

We discuss the possible consequences of using mouthwash after its expiration date below. In most cases it is unlikely to harm you, but neither is it likely to be positively impacting on your oral health!

The majority of mouthwashes contain alcohol, antimicrobials or preservatives and these affect how long those products remain active and effective.

Alcohol

Alcohol is one of the most common mouthwash ingredients. The thought is that alcohol kills bacteria that cause diseases in the mouth, but alcohol in listerine mouthwash isn’t the active ingredient. Alcohol is present to help diffuse other active ingredients, like essential oils. This not only helps to reduce plaque and gingivitis but also helps to preserve the product.

In addition, ethanol works to dissolve and disperse essential oils like thymol or menthol which break down and prevent plaque.

Generally speaking, alcohol-based mouthwashes tend to remain effective for longer, sometimes up to three years after their manufacture.

But even mouthwashes containing alcohol won’t last forever. Light, temperature, air and interaction with other ingredients will eventually trigger processes that affect taste and efficacy.

Antimicrobials (Chlorhexidine) Mouthwash

Mouthwashes may contain antimicrobials as well as, or instead of alcohol. These help to preserve the product as well as helping to reduce and prevent plaque and gingivitis.

But mouthwashes also contain a high-water content. So over time, antimicrobial ingredients will begin to dissolve and break down. As they lose their effectiveness the chances for bacterial growth increases. The mouthwash will become compromised and needs to be thrown away.

One of the main antimicrobial ingredients in mouthwash is chlorhexidine. There are disputed claims that when chlorhexidine degrades it can become harmful, so even though it has an unopened shelf life of around 5 years, it is important to closely observe the expiry date and dispose of the product when it is reached.

Preservatives – Parabens

Parabens are the most common type of preservative used in mouthwashes.  They help to prevent the growth of mold or bacteria and to keep a mixture stable.  If a mouthwash contains parabens it may well last years beyond the expiration date.

However, research in 2019 showed that parabens can enter your body through the skin. Once in your system they may cause hormonal changes that have been linked to cancer. For this reason, you may want to avoid mouthwashes containing them.

Natural mouthwashes

Concerns over the use of artificial chemicals have made natural mouthwashes increasingly popular.

If the product is purely natural then it will contain no preservatives.

You should stick to the expiry dates on purely natural mouthwashes. If there is no expiry date, mark the bottle with the date of purchase. Then watch for changes in appearance which may show the mix is breaking down. This include changes of color, general appearance, texture or smell.

Summary

  • All mouthwashes expire eventually, whether or not they have an expiration date.
  • An expiration date is a good sign, it shows testing has taken place to work out how long the product is safe and effective for. So, you should stick to it.
  • If the product does not have an expiration date, it will still expire. Mark the bottle with the purchase date and keep an eye for changes in appearance, smell or texture.
  • Always discard mouthwash that has begun to look, smell, taste or smell different. This is a sign the mix is breaking down.
  • Alcohol-based mouthwashes, or mouthwashes containing parabens, may last beyond their expiration date but see point 4.
  • Antimicrobial ingredients are likely to break down in the high-water content of a mouthwash – their expiry dates should definitely be observed.
  • Using out-of-date mouthwash is unlikely to help oral health problems, and may contribute to them through build-up of bacteria.

Expiration Dates on Dental Products?

In most conversations about expiration, decay or degradation of a product, the real center of attention are bacteria because they facilitate the breakdown of material. But as it applies to dental products, what factors more is the weakening of the ingredients over time. The result is that the products lose their effectiveness.

How Expiration Affects Toothpaste

Before using toothpaste it’s best to make sure that you’re within 2 years of the printed expiration date. It’s because after this period, the flavor and fluoride fade. Therefore, you’ll miss out on the minty taste and the fluoride won’t stick to your teeth, which lessens the plaque-fighting capabilities of your toothpaste.

Does Floss Expire?

Thankfully, floss never expires. While its effectiveness doesn’t wane, the mint flavor does subside after a year, so to get the full experience of a pleasant cleaning, be mindful of that period.

Toothbrush Expiration

An unopened toothbrush never expires, but once you start using it, you should discard it after 3 to 4 months. This is because bacteria will begin to collect on it and can cause sickness or undesirable oral conditions over time. Furthermore, if you’ve gotten sick at any time, no matter how long you’ve had the toothbrush, you should toss it.

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.