Ingredient Investigator: Charcoal in Toothpaste
Can charcoal toothpaste really whiten your teeth? Experts explain why the popular product can pose some risks to your oral health.
By Catherine Roberts
Instead of the white foam most of us normally produce when brushing our teeth, activated charcoal toothpastes coat teeth (temporarily) in a dusky slurry. Yet despite their dark hues, many companies claim the products whiten teeth.
Charcoal toothpastes are increasingly common, available not just from startup companies such as Evo and Hello but also from industry stalwarts like Colgate and Oral-B. Evidence on whether they can whiten teeth is mixed, however, and they have the potential to do more harm than good.
Here, we explain the claims of charcoal toothpaste products, how well they actually work, and the potential unintended effects.
What Is Activated Charcoal?
Activated charcoal is similar to regular cooking charcoal, but it has been heat-treated to make it extra-porous. This, in turn, makes it highly absorbent and able to trap other chemicals. Under limited circumstances, it is sometimes used in emergency medicine to treat acute cases of poisoning or overdose.
Charcoal has a long history of being used to clean teeth, thanks to its abrasiveness. According to a 2019 British Dental Journal analysis, some modern toothpastes’ labels claim that the absorbent charcoal works by binding to plaque and stains on teeth, which are then brushed away.
Does Charcoal Toothpaste Support Oral Health?
Charcoal toothpastes benefit from something of a health halo, in that people think of charcoal as a more “natural” ingredient.
“People want to believe that it’s a great alternative to toothpaste,” says Edmond R. Hewlett, DDS, consumer adviser for the American Dental Association and a professor at the UCLA School of Dentistry in Los Angeles. Unfortunately, however, “there’s no compelling evidence at all of any advantage of using charcoal toothpaste,” Hewlett says.
In the British Dental Journal paper, for example, the researchers didn’t find evidence to back up many of the claims that marketers of charcoal toothpaste made about improving oral health. In fact, many toothpastes made with charcoal do not contain fluoride, which Hewlett says has more robust evidence supporting its benefit to oral health than any other toothpaste ingredient.
“If you’re using charcoal toothpaste and there’s no fluoride, you’re missing out on the enormous benefits of using fluoride to prevent cavities,” he says.
And the authors of the paper say that even if a charcoal toothpaste does contain fluoride, the presence of the absorbent charcoal might trap the fluoride, making it less available to protect and strengthen teeth.
Can Charcoal Toothpaste Whiten Teeth?
As with other whitening toothpastes, charcoal toothpastes cannot very effectively bleach teeth to brighten them, as dentists can do with in-office bleaching treatments.
Instead, whitening toothpastes mainly work by scraping away or preventing surface stains—at least in theory. In practice, the efficacy of whitening toothpastes in general isn’t completely clear, according to a 2019 analysis.
Still, charcoal toothpastes are generally abrasive, so they do at least have the potential to scrape off stains from teeth, or to prevent them from forming in the first place, according to the British Dental Journal paper.
Studies have found mixed results with respect to how well charcoal toothpastes can whiten. One 2021 study by dentists in Iran found that charcoal toothpastes did have some whitening effects, though they were no more effective than a noncharcoal whitening toothpaste.
A 2019 Brazilian study, on the other hand, found that a charcoal-based toothpaste didn’t whiten teeth as well as other types of whitening toothpaste (such as one that used hydrogen peroxide).
In any case, in the short term, charcoal toothpastes may make teeth look worse, not better.
“The charcoal stains the plaque green, and so a lot of effort is required to brush this off the teeth,” says Linda Greenwall, BDS, a dentist and specialist in prosthodontics and restorative dentistry in London, and one of the authors of the British Dental Journal paper. “The mouth becomes black with the toothpaste, and it can be disconcerting to have this color in the mouth.”
There’s also a significant trade-off with any abrasive whitening toothpaste, including those made with charcoal: The better a toothpaste is at scraping stains off the surface of teeth, the more likely it is to also scrape and damage your teeth’s hard, protective enamel surface.
Are Charcoal Toothpastes Safe?
The main risk from charcoal toothpaste appears to be linked to its abrasiveness.
“If it’s too abrasive, over time, it can lead to sensitivity of your teeth,” says Linda Cheng, DDS, clinical associate professor at the Texas A&M University School of Dentistry.
According to the American Dental Association, some early research on charcoal toothpaste suggested that if whitening is your goal, too much abrasiveness could even backfire, by removing too much enamel and revealing the more yellowy layer of dentin beneath. Loss of enamel can also make teeth less strong and more prone to chipping, Hewlett says.
Abrasive toothpastes can also pose some additional risks to your teeth, Hewlett says. Normally, the surface of a tooth’s root is covered by the gums. But abrasive toothpastes can contribute to gum recession—meaning gum tissue pulling away from teeth and leaving the surface of the roots exposed.
That’s a problem because the exposed root is not protected by enamel and is therefore more prone to decay. And continuing to brush with an abrasive toothpaste may further damage the less protected exposed root surface.
These problems used to be more common, Hewlett says, when more abrasive toothpastes were more frequently sold in stores than they are today. Most conventional brands you find on drugstore shelves today aren’t likely to be overly hard on your teeth, he says.
Existing research has found that charcoal toothpastes on the market vary in their levels of abrasiveness, so different products may pose different levels of risk.
Still, unless a toothpaste has the ADA Seal of Acceptance, which certifies that it isn’t abrasive enough to cause harm over a lifetime of using it, it’s difficult for a consumer to tell whether a toothpaste might be too rough on their teeth. Currently, no charcoal toothpaste has earned that seal, according to a search of the ADA’s list of products.
With charcoal toothpastes, it’s probably better to avoid the risk of using a product that is potentially too abrasive, Hewlett says.
“If we’re not sure, and if there is some evidence that the abrasivity is a concern, then that should be cause for caution right there,” he says.
What About Other ‘Natural’ Toothpastes?
The popularity of charcoal toothpaste may be driven in part by the fact that many consumers are looking for personal care products, including toothpastes, with more natural ingredients.
According to market research firm Mintel, 62 percent of adults are interested in oral care products that are made with eco-friendly materials, for example. And while some of these alternative toothpastes may work well, it’s worth reiterating the importance of using a toothpaste that contains fluoride.
Cheng, for example, draws the contrast between fluoride and an often-used fluoride substitute, xylitol. Yes, she says, xylitol does have some antibacterial properties. But it still doesn’t have the cavity-fighting power of fluoride, which can help strengthen your teeth’s enamel if it has been weakened by tooth decay.
There’s one type of so-called natural toothpaste that does have a clear benefit for some people, according to Cheng. Toothpastes made without the foaming ingredient sodium lauryl sulfate (SLS) may be a good choice for people who are prone to canker sores.
A 2019 analysis in the Journal of Oral Pathology and Medicine that looked at previously published research found that although few studies have addressed this question, the evidence that does exist suggests that people with recurrent canker sores could benefit from using an SLS-free toothpaste.
In general, if you’re wondering about trying a new type of toothpaste, ask your dentist about it first, Hewlett recommends. Your dentist can help you figure out if any new oral care product might work for you. If it will be a while before your next dentist appointment, make sure you are at least using a toothpaste that contains fluoride. And—especially if it’s a whitening toothpaste—you may want to check to see whether it has the ADA Seal of Acceptance.
And remember, just because a product is marketed as more natural doesn’t mean it’s automatically better for you. “Beach sand is natural, but you don’t want to brush your teeth with it,” Hewlett says.
CR's Recommended Toothbrushes
Here, a few top-rated electric toothbrushes from CR’s tests. All Access members can also see all of our top picks in the Best Electric Toothbrushes of 2022.
Brightline 86700
Oral-B iO 7 Series
Philips Sonicare ProtectiveClean 6100
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