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Mouthwash is a very useful invention when it comes to freshening your stale or bad breath.

But it can be even more useful than that. It can kill harmful bacteria that can lead to tooth decay and gum disease as well as help boost the health of your teeth and gums.

All this being said, you don’t want to swallow mouthwash. It’s not intended to be drunk — in fact, in large enough quantities, it can be toxic.

That’s why it’s important to know what’s in that bottle of mouthwash in your medicine cabinet and what to do if someone accidentally (or intentionally) swallows any.

Let’s say that you’re typically careful when using mouthwash. You swirl it around in your mouth for the recommended time. You might wince at the taste or the sensation, but you stick it out for the health of your mouth.

If you happen to accidentally gulp down that mouthful of mouthwash, you may experience a little regret afterward in the form of a mildly upset stomach.

Many mouthwashes contain fluoride, which has been known to cause some gastric distress. You might feel queasy or nauseated, but it should go away relatively quickly.

Fluoride isn’t the only ingredient in many mouthwashes — many also contain alcohol. Some of the most common variants of alcohol in mouthwash include:

Consuming a small amount is unlikely to have any effect on you, but a larger amount could have an intoxicating effect.

If you consume a large amount of mouthwash, it can cause symptoms like dizziness or drowsiness. In serious instances, you may have trouble breathing or even have convulsions.

It’s especially important to be vigilant with children. Their bodies are smaller, so it’s much easier for them to overdose.

If an adult swallows mouthwash

If you or another adult swallow a small amount of mouthwash, you may be able to take a watch-and-wait approach.

One critical thing to remember: Do not make yourself vomit. If serious symptoms like convulsions, a rapid heart rate, or breathing problems develop, call your doctor or head to the emergency department.

If you accidentally ingest a small amount, don’t panic. If it’s just a little bit, you’ll probably be fine, or your stomach might get a little upset for a short period of time. Call your doctor and check if it will help reassure you.

A larger amount should warrant a call to your doctor or the Poison Control hotline. If you receive instructions to go to the hospital, go right away. The faster you get treatment, the better your chance of recovery.

If you visit the emergency room, they may want to run some tests before prescribing any necessary treatments.

Possible treatments for mouthwash overdose may include:

In some very serious cases, people have required kidney dialysis.

Again, if you swallow a small volume of mouthwash, it probably won’t be a big issue.

But it’s still a good idea to speak with a doctor or a poison control expert if you swallow more than a small amount. They may suggest monitoring yourself for any unusual symptoms.

If you’ve swallowed mouthwash, don’t take any medications or products like ipecac that will induce vomiting. If a child has swallowed mouthwash, don’t give them anything that will make them vomit.

It’s important to know how to use mouthwash safely. Here are a few prevention strategies that may help you:

  • Look at the packaging on mouthwash before you buy it. The Consumer Product Safety Commission established a rule in 1995 that mouthwashes containing at least 3 grams (0.11 ounces) of ethanol per package must have child-resistant packaging. Buy a bottle with this type of packaging so your child won’t be able to easily open the product.
  • Store mouthwash (and any other products containing alcohol) out of your child’s reach. Put it on a high shelf or cabinet that can be locked rather than leaving it out on the bathroom counter.
  • Go alcohol-free. Listerine makes several lines of alcohol-free versions of its mouthwash, including the Smart Rinse Kids mouthwash for children, and alcohol-free mouthwash is also available from Orajel, ACT, and Crest.
  • Forego the mouthwash until your child is older. The American Dental Association recommends that children under the age of 6 not use mouthwash because they might accidentally swallow it.
  • Carefully supervise your child when using mouthwash. Make sure they’re able to easily spit the mouthwash out into the sink so they don’t accidentally swallow it when trying to reach the basin.

One of the biggest concerns about swallowing mouthwash is the ingestion of alcohol in the product.

If you have children, be cautious of any product containing alcohol that’s in your home, whether it’s mouthwash, hand sanitizer, or other products, all of which have been known to cause cases of intoxication or poisoning.

Even a relatively small amount of ethanol, like 1 ounce, can be harmful for children, who tend to be more sensitive to it. They might develop hypoglycemia, among other effects.

If your mouthwash contains fluoride, this ingredient might upset your stomach if you swallow a significant amount.

Fluoride gels, when swallowed in large amounts, can also cause symptoms like pain, nausea, or vomiting. In rare circumstances, excessive fluoride can lead to serious problems like lowering your body’s levels of calcium.

According to the American Dental Association, some of the most common active ingredients in what they call “therapeutic mouthwash” — that is, mouthwash designed to kill bacteria that can lead to tooth decay — include:

  • cetylpyridinium chloride, an antimicrobial agent
  • chlorhexidine, another antimicrobial or antibacterial agent
  • essential oils, like menthol or eucalyptus, that may help reduce plaque and gingivitis
  • fluoride, which helps to prevent tooth decay
  • peroxide, which is often added to mouthwashes designed to help whiten teeth.

Those ingredients can be great for your teeth, gums and breath, but not so good for the rest of your body if ingested.

The ingredients in mouthwash that are most harmful when swallowed tend to be chlorhexidine gluconate, ethanol (ethyl alcohol), hydrogen peroxide, and methyl salicylate.

Even kid-friendly mouthwashes aren’t designed to be swallowed. Even though they may not contain ethanol or other types of alcohol, they may still contain fluoride and other substances that could upset their stomachs.

The bottom line: The amount of mouthwash swallowed is what really matters.

If you swallow a tiny amount of mouthwash, you probably won’t have any problems, especially if you don’t make a habit out of doing so.

But gulping down a big swig of mouthwash could cause some issues. Be vigilant about spitting the mouthwash out into the sink after you use it.

Don’t rely solely on mouthwash to preserve the health of your mouth and prevent cavities. Keep on brushing and flossing regularly and visit your dentist for regular checkups.

Depending on your child’s age, if they are under age 6 or cannot spit yet, you may want to forego the mouthwash altogether and just emphasize brushing and flossing.