This teeth whitening hack has millions of views on TikTok, but is it legit?

TikTok True or False is the answer to your burning questions about the health, beauty and fitness fads taking over your social stream. Each story breaks down a popular health trend with the help of experts and scientific research to reveal the truth and safety behind the viral “advice” you see online. You no longer have to wonder what’s really legal – or what can be skipped.
You can buy a plethora of over-the-counter teeth whitening products at your local drugstore or seek treatment from your dentist. But many TikTok users are flocking to one user’s popular video, which shows her tips for whitening teeth at home.
In the clip, which has received 2.3 million likes and more than 15 million views since it was posted, user @kris10mac claims that she praises her teeth “all the time. She continues to let viewers in on her “little secret”. It’s her own mix of mouthwash, baking soda and hydrogen peroxide.
The video has caught the attention of dentists and DIY enthusiasts alike. Wondering if this teeth whitening technique is up to your dentist’s standards? Spoiler alert: You’re better off sticking with store-bought teeth whiteners.
“There are many ways to keep your teeth bright, white and healthy without resorting to methods that may be inherently dangerous or unscientific,” American Dental Association (ADA) spokesperson and pre director Erinne Kennedy, DMD, MPH, MMSc – PhD, of the University of Kansas City School of Dental Medicine dental education, tells Shape.
Read on to learn why you may not want to try viral hacking yourself and what to do.
In the popular video, the creator explains the process of a three-ingredient teeth whitening solution she makes and uses at home. She suggests using any bottle of mouthwash you can get your hands on – her choice is Crest. According to Cleveland, she used or emptied about a quarter of the bottle of mouthwash and then filled the bottle with hydrogen peroxide, an antiseptic liquid that comes in a brown bottle and is commonly used to treat skin wounds and kill bacteria in clinics. Finally, she sprinkled about a teaspoon of baking soda directly into the clear mouthwash bottle.
TikToker advises viewers to mix the bottles together and then rinse and brush their teeth with the contents every night. “It’ll make your teeth sparkle,” she says. And her “pro tip” for special events? Brush your teeth with the mixture poured on your toothbrush for that “extra sparkle” effect.
Can mixing mouthwash, hydrogen peroxide and baking soda whiten my teeth?
This mixture may whiten teeth, but it may cause side effects, Sharon Huang, DDS, a cosmetic dentist in New York City, tells Shape.
Experts explain that each of the ingredients used by TikToker to whiten teeth are fine. Hydrogen peroxide is actually the main active ingredient in many products whitening products, and it does whiten teeth, Huang says. Baking soda is used in dental care products, including some toothpastes Kennedy also noted. A quality mouthwash is a key ingredient in oral health because it freshens breath and fights gingivitis (gum disease), tooth decay and plaque, according to the ADA.
But just because these ingredients can help whiten teeth doesn’t mean they can be used at will, or in any combination. They must be used in specified volumes under specific conditions to ensure safety and effectiveness, and Huang is concerned about the “self-fabricated” DIY approach that includes vague measurements, not to mention that hydrogen peroxide itself is not a stable ingredient.
Not to mention, hydrogen peroxide itself is not a stable ingredient, Huang says, and its effectiveness decreases when exposed to light (which is why it comes in that brown bottle). So, as the viral TikTok video shows, it’s not as potent when added to a clear bottle of mouthwash.
Huang explains that it also oxidizes quickly, which means it turns into water and oxygen. That’s why even a regular bottle of hydrogen peroxide that sits on the shelf for a long time may not actually whiten teeth.
In addition, because hydrogen peroxide is a reactive substance, it may also interact with other ingredients in the mouthwash in unknown ways, Huang says.
If you add it correctly – for example, in a whitening strip – hydrogen peroxide can whiten your teeth. “My concern with this trend is that people are mixing these together at home,” Huang says. “There’s no standard about how you’re supposed to do that.”
Is this teeth whitening hack safe?
Kennedy said there’s no real way to tell if the hack is safe. “The simple answer is we don’t know,” she says. “Because this is a DIY recommendation, it doesn’t have the ADA seal of approval. Products with the ADA Seal of Approval have been shown to be safe for your teeth and other tissues in your mouth.”
That said, there could be consequences for attempting a hack at home. Kennedy says, “If a chemical is ingested too much, it can cause gum [gum] burns.” She adds that in addition to tissue burns or irritation, untested chemical mixtures can cause permanent damage to teeth, including damage to tooth enamel, noting that it’s similar to skin contact with chemicals.
It is more effective to use active ingredients such as hydrogen peroxide in the form of whitening strips or for professional whitening, rather than mixing your own mixture (including hydrogen peroxide) at home.
It’s also important to remember that if a substance dissolves your tooth enamel, your body can’t produce new enamel, Kennedy added. “If you’re trying this and you’re an adult, your permanent teeth won’t regenerate, so taking care of your teeth and making sure there’s no damage is absolutely paramount,” she says.
You can safely mix mouthwash, hydrogen peroxide and baking soda to whiten your teeth: right or wrong?

Both Kennedy and Huang do not recommend trying this viral TikTok hacking technique to get whiter teeth. Using the substances suggested in the clip without examination can have negative health effects, even if your teeth do get brighter in the short term.
It’s not worth the risk to try this mixture on your own. You’re better off going to the drugstore and buying a mouthwash that already contains whitening ingredients, Wong says. In addition, she adds, store-bought teeth-whitening products may also include disease- and cavity-prevention benefits.
If you want to decide how to whiten your teeth, you can also seek advice from your dentist. “Your dentist is an expert in your teeth, and they can provide you with targeted solutions to help you look your brightest,” Kennedy says.