Charcoal toothpaste and sensitive teeth: what the evidence shows, and why dentists are wary.

Charcoal toothpaste gives a sensitive tooth little to gain: in the one randomised trial of charcoal products in people, a charcoal toothpaste and a charcoal powder changed tooth colour no more than an ordinary fluoride toothpaste over 14 days¹. The usual warning, that charcoal scrubs enamel away, is disputed by laboratory studies that disagree with one another²³, and the clearer cost for a sensitive tooth is that many charcoal products carry no fluoride at all³. S3 Sensitivity Science™ has no charcoal in its ingredient list and keeps full adult-strength fluoride, 1450 ppm as sodium monofluorophosphate.

What was checked16 peer-reviewed studies and reviews, the NHS, the Oral Health Foundation, the ASA rulings register, and product information as published by each brand

Does charcoal toothpaste whiten teeth?

Not measurably more than an ordinary toothpaste, on the evidence available¹. The best test so far comes from Brazil. In their randomised trial, Ribeiro and colleagues assigned 56 volunteers to four groups of 14 for a fortnight: brushing with an activated charcoal powder, brushing with an activated charcoal toothpaste, brushing with a regular fluoride toothpaste, or whitening with a 10% carbamide peroxide gel¹. Colour was measured with an instrument, by eye against a shade guide and as a whiteness index. On all three, both charcoal products moved the colour about as far as the regular toothpaste did, and the peroxide gel did best and left volunteers the most satisfied¹. The authors, who declared no competing interests, called the charcoal effect minor and unsatisfactory and concluded that charcoal products should be discouraged¹.

That randomised trial did not recruit people for sensitive teeth, and neither has any other. Two PubMed searches run for this page in September 2026, pairing charcoal toothpaste or powder with sensitivity and hypersensitivity terms, returned eight and seventy-two records, and the Brazilian fortnight above was the only one of them carried out in people. A 2021 review of charcoal products sold in Brazil, whose funding is not stated, counted 22 published articles on charcoal dentifrices and powders, found 21 of them to be in vitro studies, and described the single clinical study as sponsored by a charcoal product and run without a control group⁵.

The laboratory colour studies point the same way. In tea-stained cattle teeth, two charcoal dentifrices changed overall colour no more than a regular toothpaste at one week or at a month's follow-up, and the authors, who declared no conflict, wrote that the products lacked the whitening effect they claimed⁶. In a laboratory study on 60 cattle incisors whose authors declared no conflicts, a charcoal whitening paste brushed for 14 days produced, in the authors' words, a colour change inferior to a regular non-whitening toothpaste, and roughly half the change a carbamide peroxide gel produced⁷. A 2023 systematic review of 11 in vitro studies, whose authors declared no competing interests, concluded that charcoal toothpastes whiten less than the alternatives, while rating the risk of bias in those studies medium to high².

What charcoal is supposed to do is lift stain, either by abrasion or by soaking up pigment. A 2024 laboratory study from São Paulo, whose authors declared no competing interests, set out to separate those two actions on stained cattle enamel, and found that three charcoal toothpastes and a charcoal powder limited staining about as well as a conventional toothpaste, not better⁸. None of that touches the tooth's own colour underneath. The Oral Health Foundation's advice on tooth whitening puts a real change of shade in the hands of the dental team⁹.

Is charcoal toothpaste abrasive enough to hurt sensitive teeth?

Nobody has measured that in people, and the laboratory studies come down on both sides²³. It matters to a sensitive tooth because wear is one route to exposed dentine: the Oral Health Foundation lists brushing too hard or with a hard toothbrush, and acid wear, among the common causes of sensitivity¹⁰. The page on gum recession and brushing covers the brushing side of that.

The familiar warning that charcoal scrubs enamel away is weaker than its reputation, and this page will not repeat it as a fact. Here is what each side of the disagreement measured.

Studies that found more wear. The 2023 systematic review reported that most of its 11 in vitro studies agreed on a higher abrasive potential for charcoal toothpaste². In a Norwegian laboratory study on 30 extracted human molars, two fluoride-free charcoal powders scored relative dentine abrasivity values of 75 and 66, against nine for the whitening toothpaste used as the reference and 100 for the standard ISO slurry¹¹. The authors, who declared no conflict, judged both within ISO limits and cautioned that two powders cannot stand in for charcoal sold in a tube¹¹. In a laboratory study on 60 cattle enamel blocks, whose funding is not stated, a charcoal toothpaste, a charcoal paste with titanium dioxide and a charcoal powder all wore more enamel than a regular toothpaste, but so did a titanium dioxide whitening paste with no charcoal in it, and none of them made the surface rougher¹². On eroded laboratory samples, three of five charcoal toothpastes caused the most wear while two stayed close to a conventional fluoride toothpaste, and the authors, who disclosed no conflict, suspected the pyrophosphate some of those pastes also contain¹³. The São Paulo laboratory study found enamel wear after 100,000 brushing cycles lowest with a conventional toothpaste, intermediate with three charcoal toothpastes and highest with a charcoal powder⁸.

Studies that found no more wear. A Zurich laboratory study that used radiotracers on 12 charcoal toothpastes, whose authors declared no conflict, measured relative dentine abrasivity from 24 to 166 and enamel abrasivity from 0 to 14, and reported that those values did not differ significantly from ordinary commercial toothpastes tested before; three of the 12 scored above 80, the band the authors call high abrasion³. In a laboratory comparison of nine fluoride toothpastes, six with charcoal, charcoal pastes were not significantly more abrasive or more toxic to cells, and the authors declared no conflicts⁴. In a laboratory test on 30 coffee-stained premolars, two charcoal whitening pastes and a whitening paste without charcoal abraded the surface to the same degree, with no conflict declared¹⁴. The tea-stained cattle teeth brushed with two charcoal dentifrices were no rougher than those brushed with a regular toothpaste⁶. And in an erosion and brushing model whose funding is not stated, none of seven charcoal toothpastes caused more enamel or dentine loss than brushing with artificial saliva¹⁵.

Why the results differ is not a mystery. The products differ: in one laboratory study alone the spread ran from 24 to 166³. Powders are not pastes, and in both laboratory studies that tested loose charcoal powder, the powder wore more than the ordinary paste it was set against¹¹⁸. The comparisons differ too, since a charcoal paste measured against saliva, a regular paste, a whitening paste or a standard slurry is being asked four different questions. And an abrasivity score is a laboratory number, not a measure of anyone's pain; the page on whitening toothpastes and RDA explains what the score can and cannot tell you.

What do many charcoal products leave out?

Fluoride. Of the 12 charcoal toothpastes in the Zurich laboratory study, six listed no fluoride compound at all, and the authors wrote that the lack of fluoride in many of them can leave consumers with a less beneficial product³. Of 36 charcoal dentifrices and powders sold online in Brazil, only three contained fluoride, according to a 2021 review whose funding is not stated⁵. Both powders in the Norwegian laboratory study were fluoride-free¹¹.

The fluoride, not the charcoal, is what tracked protection in the laboratory. In the laboratory erosion and brushing model, whose funding is not stated, the more fluoride a slurry carried the less enamel and dentine it lost, a correlation of −0.77 for enamel and −0.91 for dentine, and the three fluoride-free charcoal pastes did no better than saliva¹⁵. Charcoal does not seem to cancel fluoride out where both are present: in the nine-paste laboratory comparison, the charcoal toothpastes had 93% to 102% of their labelled fluoride available, and in the Norwegian tests neither powder soaked fluoride up from solution over 24 hours⁴¹¹.

The NHS tells adults to use a toothpaste with at least 1,350 ppm fluoride and to check the packaging for the amount¹⁶. A charcoal product with no fluoride line cannot do that part of the job, whatever else it does.

Four charcoal products turned up on UK brand pages in September 2026, and they are set out below with a sensitivity toothpaste for comparison, based on what each brand states about its own formula. This page compares ingredients and stated actions only, not clinical performance. Prices and formulations may change, always check the pack.

So two of the four charcoal products declare a fluoride salt, and one of those two gives its level. Georganics' charcoal paste with hydroxyapatite lists 1350 ppm sodium fluoride beside its charcoal, which answers the fluoride objection this page makes, and a shopper who wants charcoal can have fluoride with it. Curaprox's page for Black is White says the paste "includes fluoride" and lists sodium monofluorophosphate without a level. The two fluoride-free Georganics products describe themselves as "ideal for sensitive teeth and gums" and "safe for sensitive teeth", which this page reports as the brand's words without testing them. Both brands file these products under whitening rather than under sensitive teeth. A charcoal paste from a national brand on the Boots shelf was on the list to read as well, and Boots' pages refused automated access on the day, so no such row exists here and none was invented.

What do dentists actually advise?

No UK guidance body has published advice on charcoal toothpaste that this page could find; the caution in print comes from dental researchers writing in journals. A search of the NHS website for "charcoal toothpaste" in September 2026 returned five general pages, among them keeping teeth clean, children's teeth and braces, and no page about charcoal. The Oral Health Foundation's pages on sensitive teeth and on tooth whitening, read the same month, do not mention it either. The British Dental Association's site search refused automated access, so this page cannot say what it holds. The advertising regulator's rulings register, searched for "charcoal", holds one ruling about influencer clothing adverts and one informally resolved case involving a home and garden retailer, and nothing about a toothpaste or a tooth powder¹⁷.

For UK dental teams the obvious reference is a 2019 review in the British Dental Journal by UK-based authors. Its abstract, in a record with no funding statement, calls charcoal toothpastes and powders fashionable, says they are sold for toothbrushing, surface stain removal and what manufacturers call whitening, and notes that patients often ask their dental team about them and that the advice they get is often empirical¹⁸. The full text was behind a login when this page was researched, so its conclusions are not quoted here.

A 2017 literature review in the Journal of the American Dental Association is plainer. None of the studies the review found met its own bar of controlled trials with at least three months of follow-up; it judged the clinical and laboratory data insufficient to substantiate the safety and efficacy claims made for charcoal dentifrices; one-third of the 50 charcoal products it surveyed online contained bentonite clay; and its authors, whose funding is not stated, advise dental clinicians to tell patients to be cautious¹⁹. The Brazilian trial authors went further and wrote that charcoal products should be discouraged, on whitening effect and satisfaction alone¹.

That is why this page's title says dentists are wary and not that they advise against charcoal: the published caution is real, and it is written by researchers and reviewers rather than issued by a UK guidance body.

What does S3 carry that a fluoride-free charcoal paste does not?

Full adult-strength fluoride and three declared actives, and no charcoal. S3's formula combines a nerve-calming active, 5% potassium nitrate, with 10% nano-hydroxyapatite and 5% biomimetic hydroxyapatite, both inclusion levels as solution, and 1450 ppm fluoride. S3's fluoride comes as sodium monofluorophosphate, picked because that salt does not react with the calcium of the two hydroxyapatites in the same paste.

The fluoride in S3 is there for decay protection, and this page does not present it as a sensitivity treatment. Nor does fluoride set S3 apart from every charcoal paste: the Georganics hydroxyapatite and charcoal paste in the table lists 1350 ppm sodium fluoride too.

S3 publishes no abrasivity figure either, so this page cannot say S3 is gentler on enamel than a charcoal paste, and does not. Hydroxyapatite in a formula does not promise a low score: in a laboratory brushing test of six desensitising pastes on dentine discs etched with lemon juice, whose funding is not stated, the paste containing zinc carbonate and hydroxyapatite removed the most dentine²⁰. S3 was not one of the six, and nobody has published an abrasivity measurement for it. The page on hydroxyapatite toothpaste every day looks at that ingredient's abrasivity question in more depth.

What should someone with sensitive teeth do instead?

Keep the fluoride, go gently, and take colour to a dental professional.

Read the fluoride line first. Whatever the tube looks like, the NHS figure for adults is at least 1,350 ppm, and after brushing the NHS advises spitting out the excess and not rinsing, so the fluoride stays on the teeth¹⁶. If a black paste or powder names no fluoride salt, it is not covering that.

Use a toothpaste made for sensitivity. For sensitive teeth the Oral Health Foundation points to toothpastes containing potassium nitrate, potassium citrate or stannous fluoride, with a soft brush, gentle small circular strokes and a wait of at least an hour after acidic food or drink before brushing¹⁰. How acid softens the surface is covered in the Journal's page on tooth enamel erosion.

Be slower with powders. In the Brazilian randomised trial the charcoal powder was the product volunteers rated least comfortable and least easy to use, and in the São Paulo laboratory study it wore enamel more than the charcoal pastes did¹⁸.

Take colour to the dental team. Stain that brushing will not shift is worth showing to a dentist or hygienist, and a change of shade is, for the Oral Health Foundation, a job for a registered dental professional who checks teeth and gums first⁹. The hub page on how to whiten sensitive teeth sets out that route, and the Journal's page on sensitive teeth after whitening covers what to expect afterwards.

Know when the paste is beside the point. The Oral Health Foundation says to see a dentist when the pain is severe, when it has gone on for more than a few weeks, when it began suddenly or when a single tooth is the one that hurts, since decay, a crack, gum problems or an infection can show up that way¹⁰.

Frequently asked questions

Can charcoal toothpaste make sensitive teeth worse?

Nobody has tested it in people whose teeth were already sensitive. The one randomised trial that asked about tooth sensitivity, in 56 volunteers over 14 days, found no significant difference in its risk or intensity between the charcoal products, the regular toothpaste and the peroxide gel, with sensitivity most common in the gel group¹. The laboratory evidence on abrasion is split, and the clearer risk is a charcoal product that carries no fluoride²³.

Is charcoal powder worse than charcoal toothpaste?

On the little evidence there is, the powder does not come out ahead. Volunteers in the Brazilian randomised trial rated the powder lowest for comfort, ease of use and whitening satisfaction¹. In laboratory tests a charcoal powder wore enamel more than three charcoal toothpastes in one study, and two fluoride-free powders scored well above a whitening paste for dentine abrasivity in another, though within ISO limits⁸¹¹.

Does S3 contain charcoal?

No. S3's published ingredient list has no charcoal; its declared actives are 5% potassium nitrate and two hydroxyapatites, and it carries 1450 ppm fluoride as sodium monofluorophosphate.

Is a charcoal toothpaste with fluoride a reasonable choice?

It removes the objection about fluoride, and not the one about evidence. A paste such as Georganics' hydroxyapatite and charcoal paste lists 1350 ppm sodium fluoride, which meets the NHS figure for adults, while Curaprox lists a fluoride salt on Black is White without a level. What the charcoal adds is still unproven: in the one randomised trial, charcoal changed tooth colour no more than an ordinary fluoride toothpaste¹. This page gives no verdict on either product.