Wait, Wait, Wait... Should We Be Smelling Our Floss?

If we all had a dollar for every time a gross, fascinating, and oddly informative video found its way to our For You Pages, we’d be rich. Sometimes, you take mental note and keep scrolling. Others, the video stops you in your tracks. Case in point? When a dental hygienist recently went viral for telling viewers to floss their teeth — and then smell the floss. If your floss stinks, you could have periodontal disease. Sounds pretty gross, but is this a health hack that actually has merit? After all, it was coming from someone who spends all day around teeth.

Scary Mommy asked a few more (real-life) dental experts to weigh in, from what kind of smell we’re talking about here to signs you can look for that don’t involve the stinky string sniff test. What they had to say might just surprise you.

First things first: How often should we be flossing?

If the mere thought of flossing makes you a little panic-stricken that you aren’t flossing enough, you’re not alone (🫣). But how much is enough? According to the American Dental Association, in addition to brushing twice a day, you should be cleaning between teeth with floss or another interdental cleaner once a day.

Is floss-smelling actually a thing we should do?

Could sniffing our floss really be a valid diagnostic tool when it comes to periodontal disease? The experts we tapped agree that while it’s an idea that might make you say “ew,” it’s not without merit: A foul smell coming from your floss can be a sign of something deeper.

“As strange as it sounds, yes, smelling your floss after use can genuinely give you early clues about gum disease. It's not just an internet gimmick or gross curiosity. There's real microbiological science behind it,” confirms Dr. George Wu of ClearChoice Dental Implant Center in West Covina, California. A board-certified prosthodontist who specializes in tooth replacement, Wu is very familiar with periodontal disease — it’s the No. 1 cause of tooth loss in adults.

“If you notice a foul odor on your floss, especially a smell that's consistently coming from the same area, it's often due to anaerobic bacteria living deep in the gum pockets,” he elaborates. “These bacteria thrive in low-oxygen environments, and they produce something called volatile sulfur compounds (VSCs) as waste. These VSCs are the culprits behind that ‘rotten egg’ smell, specifically gases like: hydrogen sulfide (the classic rotten egg smell), methyl mercaptan (smells like decaying cabbage or garlic), and dimethyl sulfide (has a foul, sweet, sulfuric odor). These compounds aren't just smelly, they're toxic to gum tissue and are directly involved in the progression of periodontal disease.”

Yep, that’ll give you the ick. But that bad smell on your floss? As Wu points out, “it might literally be the scent of gum tissue breaking down.”

So, does a bad smell definitely mean periodontal disease?

While stinky floss is a pretty good indicator of periodontal problems, all of the experts agree that you should think of it as a hint that something is up — but that something isn’t necessarily always going to be as serious as gum disease.

“Everyone’s oral microbiome is different, and occasional bad smells don’t always indicate disease,” says Dentistry. One’s patient relations manager, Danielle Nuss, who has over 21 years of experience as a dental hygienist with 18 years in a specialized periodontal practice. “[Smelling your floss] is not a scientific diagnostic method, but it can be an informal clue that something might be off in your oral health.”

Dr. Karen Man, a public educator, dentist, and CEO of SmileGrove Dental, also feels that smelly floss is more of a red flag than a reliable way to diagnose anything specific. “More dependable signs of gum problems include bleeding when brushing or flossing, swollen or tender gums, gum recession, or ongoing bad breath,” she tells us. “If your floss regularly smells bad, it’s a good idea to book a dental checkup. Catching gum disease early is the best way to keep it from getting worse.”

Teeth that feel loose, noticeable tartar buildup, pain when chewing, and tooth sensitivity are other symptoms that the experts say could point to a potential oral health issue. “These symptoms should prompt a visit to your dentist, even if your floss doesn’t smell,” emphasizes Nuss.

What are some other possible reasons for dental odor?

Stinky floss doesn’t always indicate periodontal disease. Again, this is why it’s so important to keep regular appointments with your dental care provider: They’ll be able to identify issues early.

Periodontal disease isn’t the only reason your mouth may smell a little funky. According to Dr. Fatima Khan, dentist and co-founder at Riven Oral Care, a number of reasons could be to blame, like:

• Tooth Decay. If there's decay between your teeth or underneath a dental crown, you might notice your floss having an unpleasant smell or even getting stuck. When you have dental decay, especially a large cavity, which is a hole in your tooth, bacteria and food particles can continue to get trapped there and lead to bad breath and foul floss odor.
• Broken Fillings. Broken or fractured fillings can be a haven for bacteria, leading to a foul odor when you floss. When you floss, you may notice the filling pulling up or getting stuck.
• Halitosis (Bad Breath). When your mouth is in a state of imbalance due to poor hygiene, poor habits, stress, medication as well as other issues, you will notice the build-up on your teeth will be thicker, stickier, yellower and have a foul odor, and you will be more prone to anaerobic bacteria, which produces volatile sulfur compounds that cause foul odor.

Of course, all of these issues still warrant a convo with your dentist. To help with halitosis at home, Khan says you need to address the imbalance in your oral microbiome by taking oral prebiotics and probiotics supplements and by eating probiotics-rich foods such as yogurt, sauerkraut, kefir, sourdough bread, and kimchi. And, as much as possible, try to breathe through your nose and not mouth, as less saliva (a natural byproduct of mouth-breathing) can lead to an overgrowth of anaerobic bacteria.

OK, calling my dentist. What else should I do?

First, remember that funky-smelling floss is a signal, not a diagnosis. So don’t panic, but don’t ignore it either. There are definitely things you can do between dentist visits to keep your mouth healthy and minimally smelly.

“If you consistently notice a bad smell on your floss, review your oral hygiene routine to ensure you are brushing and flossing effectively,” says Nuss. “In some cases, adjunctive tools such as a water flosser or interdental brushes may be necessary to properly clean certain areas.”

Dr. Sandip Sachar, who has been practicing general and cosmetic dentistry in New York City for over 20 years, says consistency should be your default response if you notice your floss smells bad.

“Generally, all this means is you need to floss that area more (at least once or, if needed, twice a day). As you floss it more, you'll notice your used floss won't stink anymore because the plaque buildup is not sitting there for long periods of time decomposing,” she says.

Khan agrees that the emphasis should be on proper oral hygiene. If your gums are at the root of your issues, though, and you need a bit of relief until you can get to your dentist, she has a pro tip.

“If you have bulbous, red, bleeding gums, I would recommend rinsing with warm salt water (Himalayan salt preferably) to reduce inflammation,” she recommends. “Dissolving half a teaspoon of salt in warm water forms a gentle yet effective mouth rinse. Saltwater not only cleanses the affected area but also reduces inflammation and fosters an environment that inhibits pathogenic bacterial growth.”