Does Mouthwash Expire - Is It Still Safe to Use?

Does Mouthwash Expire - Is It Still Safe to Use?
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Does Mouthwash Expire - Is It Still Safe to Use?Clinical Content Reviewed by Dr. Jay Khorsandi, DDS
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Table of Contents

  1. How Long Does Mouthwash Last
  2. Does Expiration Vary by Mouthwash Type
  3. ‘Beyond Use Date’ for Mouthwash
  4. How Effective is Mouthwash after Expiration
  5. Safety Beyond Expiration Date
  6. References

If you have an over-the-counter (OTC) or prescription mouthwash from two or three years ago, you may wonder whether it’s safe and effective to use it now. Generally, chemical formulations for ingestion or use on the skin have a useful shelf life, and oral rinses are no exception.

The stability and strength of mouthwashes vary by brand and ingredients and whether it’s designed for cosmetic or therapeutic applications. In generally, it’s best not to use such a product after its expiration date.

How Long Does Mouthwash Last?

The U.S. Food and Drug Administration (FDA) sets the standards upon which mouthwash manufacturers can estimate the useful shelf life of their products. To meet the FDA's strict approval criteria, drug makers run tests in specific conditions and document key results, including the drug’s stability profile.

Mouthwash stability tests indicate how long the active ingredients in a product retain their potency and usefulness to the consumer. Some ingredients decompose and lose strength faster than others, which is why different formulations made the same date may have different expiry dates.

For any mouthwash, the “use before date” is the date on which the manufacturer can’t guarantee its effectiveness and safety. Drug makers usually print this information on the product’s label, so be sure to read it if you suspect your opened or used mouth rinse is past its expiry date.

Many of these products last from a few months to two or three years. For example, some Listerine solutions expire 12 months after opening.

Does Expiration Vary by Mouthwash Type?

There are different types of mouthwash for different purposes. Formulations for strengthening teeth and preventing tooth decay have fluoride as the base element. While some products comprise pain-relieving medication, others contain antimicrobials—chemical agents that improve your breath by containing bacterial growth in your mouth.

The unique chemical composition in each type of these products is responsible for their unique stable shelf life. Oral rinse manufacturers can extend the useful life of their cosmetic or therapeutic formulations by incorporating a stabilizing agent.

For example, fluoride usually reacts with other active toothpaste or mouthwash ingredients while in storage. It becomes less effective over time, but it can be stabilized to extend its useful shelf life.

In a two-year study involving school children, stabilized stannous fluoride was more effective in reducing tooth decay than a sodium fluoride product without a stabilizer.

What is the ‘Beyond Use Date’ for Mouthwash?

Some prescription mouthwashes have a beyond-use date (BUD), which is not the same thing as the expiry date. The pharmacy that fills your prescription determines the BUD based on factors like your dosage, the solution’s rate of decomposition after preparation, and storage conditions.

After this date, you’ll usually need to discard any remaining mouthwash and get a refill.

In one study, researchers extended the BUD of an antimicrobial mouthwash by a month on average after adding a stabilizer to the formulation. This modification meant fewer trips to the pharmacy for patients using the oral rinse to prevent opportunistic mouth infections.

Also, it’s possible to extend the stability and effectiveness a mouthwash ingredient by dispensing and storing it separately from other key ingredients for a prescribed dose.

For example, one study by the American Society of Health-System Pharmacists recommends a BUD of 21 days for magic mouthwash with lidocaine and two other ingredients. However, packaging, storing, and administering lidocaine in a separate dosage unit can prolong its BUD to 90 days.

Lidocaine is a swash-and-spit oral rinse for relieving pain from mouth sores or irritation.

Given alcohol is an active ingredient, most types of mouthwash are a majority of water and the antiseptic will begin to break down, after two to three years.

How Effective is Mouthwash after Expiration?

The ingredients in a mouthwash undergo gradual decomposition during storage and also on exposure to air once you open it. Reactions between the various active chemicals usually result in formulations that differ in benefits and effects compared with the original product.

These chemical changes reduce the effectiveness of any mouthwash over time. As far as the manufacturer and the FDA are concerned, such a product doesn’t offer any therapeutic value after expiry.

Safety Beyond Expiration Date

When the active ingredients in your mouthwash expire, they become less effective, but not necessarily toxic. As such, you’re unlikely to fall ill because you used expired mouthwash, unless it got contaminated with hazardous material in storage.

Using ineffective medication can still impact your health negatively, so it’s not a safe habit either. For instance, continued use of expired antimicrobials usually causes poor treatment outcomes.

If you’re on prescription antimicrobials, you want these to work and protect you from oral infections.

It’s best not to use expired oral rinses. Not only are such products ineffective, but also using them may also worsen your oral health.

In case you reach the beyond-use date before finishing your prescribed dose, discard the medication and get a refill.

References

Part 355 Anticaries Drug Products for Over-the-Counter Human Use. The U.S. Food and Drug Administration (FDA). Date Fetched: August 24, 2021

Frequently Asked Questions. Listerine. Date Fetched: August 25, 2021

Stabilized Stannous Fluoride Dentifrice in Relation to Dental Caries, Dental Erosion, and Dentin Hypersensitivity: A Systematic Review. American Journal of Dentistry. Date Fetched : August 25, 2021

Reformulation of Extemporaneous Tetracycline Mouthwash to Improve Its Stability for Pemphigus Patients. Journal of Asian Association of Schools of Pharmacy. Date Fetched : August 25, 2021

Beyond-Use Dating of Lidocaine Alone and in Two "Magic Mouthwash" Preparations. American Journal of Health-System Pharmacy. Date Fetched: August 27, 2021

Disclaimer: This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to serve as dental or other professional health advice and is not intended to be used for diagnosis or treatment of any condition or symptom. You should consult a dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.

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