Your sensitivity toothpaste was reformulated: how to find an equivalent by active ingredient.

An equivalent for a reformulated sensitivity toothpaste is a tube that matches the old one on the four things a pack prints: the desensitising active, the level of that active, the fluoride salt with its strength, and whether water is in the base. Most tubes on the UK shelf cannot be matched on all four, because most of them do not print the level, so the honest search is for the same active with the other three fields checked, and for the nearest mechanism when even that fails. S3 Sensitivity Science™ prints a figure beside each of its three actives and names its fluoride salt, which makes its own tube easy to fingerprint, and on those printed fields it is a change of formula for anyone coming from another tube on this page, not a match.

What was checkednine peer-reviewed studies, product information as published by each brand, the cosmetics regulation as retained in Great Britain, UK government guidance, the Oral Health Foundation and the NHS

What makes one sensitivity toothpaste an equivalent of another?

A match on four fields that a pack prints, and on a fifth that no pack prints at all. The four are the ones you can copy from the back of an old tube, or from a photograph of it, onto the back of an envelope:

• The desensitising active. This decides the mechanism. A potassium salt is thought to quieten the nerve, while stannous fluoride, arginine and bioactive glass work at the open ends of the dentine tubules, so two tubes with different actives are two different treatments whatever the front of the box says.
• The level of that active. The percentage, where there is one. It is the field most often missing, and a blank on one tube cannot be checked against a figure on another; the page on where the potassium nitrate percentage comes from explains why the figure that is printed is almost always the same one.
• The fluoride salt and its strength. Sodium fluoride, sodium monofluorophosphate, or stannous fluoride with a little sodium fluoride, and the parts per million. It reads like a decay-protection detail, and the section on fluoride below explains why it belongs in the fingerprint.
• Water in the base. Whether Aqua appears in the list. In the recorded rows, every bioactive-glass tube lists no water and eleven of the twelve potassium nitrate tubes do.

The fifth field is the chemistry of the paste around the active, and nothing on a pack describes it. The people who build these pastes treat it as the part that makes a formula work. A 2004 development account by scientists employed by a toothpaste manufacturer, laboratory work rather than a test in people, describes an activated silica designed to raise how much potassium ion a 5% potassium nitrate paste made available⁵. A decade earlier, and again from bench work on dentine, scientists employed by the same manufacturer reported that what their potassium nitrate paste laid down over the tubules came from the base, a copolymer and silica, and was not the potassium salt⁶. Neither laboratory paper, both written by the manufacturer's own scientists, compared what two 5% tubes do in a person's mouth⁵⁶. What both show is that the companies making these pastes do not treat two identical percentages as one product.

An extra ingredient beside the same active makes a different formula as well, and in one tested case a measurably different one. In an industry-funded double-blind randomised trial of 127 adults, a paste combining 5% potassium nitrate with 2.18% aluminium lactate reduced sensitivity more than the same-strength potassium nitrate paste without it, at four weeks on the air stimulus and at eight weeks on both stimuli⁷. On the shelf, the ingredients sitting beside a potassium nitrate active are rarely that clear-cut: zinc citrate appears on two of the lists and zinc gluconate with a group of enzymes and proteins on a third, and the lookup below treats them as part of the base and says where they are.

What "equivalent" has meant in practice is visible in the two trials that came closest to testing it. The page on whether the market leader has changed its formula walks through the first of them, together with the five-minute check of an old tube against a new one. In short, a double-blind randomised trial set an established potassium citrate paste with triclosan and zinc citrate added against the original version, and over eight weeks, in 56 adults who completed, both versions improved and most of the gaps between them fell short of significance, with no placebo arm against which to size either³.

The second trial came out of the searches run for this page, and it makes the point more sharply. In an examiner-blind randomised non-inferiority trial run and paid for by the manufacturer of both pastes, 304 adults brushed with one of two toothpastes holding the same 5% calcium sodium phosphosilicate, one delivering its fluoride as sodium fluoride and the other as sodium monofluorophosphate⁴. After four and eight weeks both groups had improved on every measure and no gap between them reached significance, yet the manufacturer's own trial could not declare the sodium fluoride version no worse: at eight weeks the upper confidence limit of the difference on the pain scale was 7.4 mm, against a margin of 6 mm fixed in advance⁴. That is what a properly designed like-for-like test looks like, and it shows how much harder "the same" is to establish than "no difference found".

The counts in that table come from the published ingredient lists and declared concentrations of each row, read on the ninth and tenth of September 2026.

Why does the pack name the fluoride but not the level of the active?

Because the law on cosmetics in Great Britain says a good deal about fluoride and nothing about potassium nitrate. Toothpaste counts as a cosmetic product in the government's consumer guidance, which requires a list of ingredients on the container or the packaging and sets out the other things a pack must show; the amount of each ingredient is not among them².

The detail is in Annex III of the cosmetics regulation as retained in Great Britain, the list of substances a cosmetic may contain only under stated restrictions. We read the latest revised text on legislation.gov.uk in September 2026, when the page listed its most recent amendment as 15 August 2026 and recorded no outstanding effects¹. Three of its entries are the fluoride salts found on UK sensitivity tubes: sodium monofluorophosphate at entry 27, sodium fluoride at entry 31 and stannous fluoride at entry 35¹. Each is allowed in oral products up to 0.15% calculated as fluorine, with the combined fluorine held to the same ceiling when salts are mixed, and each carries its own obligatory label wording, "Contains sodium monofluorophosphate", "Contains sodium fluoride" or "Contains stannous fluoride"¹. A toothpaste containing between 0.1% and 0.15% fluorine must also tell parents that children of six and under should use a pea-sized amount under supervision, unless the pack is already labelled as not for children¹. A 1450 ppm paste, the strength most rows on this page print, is 0.145% fluorine and sits inside that band.

Potassium nitrate has no entry. Searched on the same page, the annex holds nothing for potassium nitrate, potassium chloride or potassium citrate, and nothing for arginine, calcium sodium phosphosilicate or hydroxyapatite; potassium appears only as a hydroxide, a chlorate, three fluorine compounds and a peanut-oil derivative¹. Strontium chloride, by contrast, does have an entry, with its own ceiling for oral products¹. A substance with no entry carries no set label phrase and no ceiling in that annex, so nothing there obliges a maker to name a potassium nitrate level, and nine of the twelve potassium nitrate tubes recorded do not.

Two things follow for anyone matching tubes. The fluoride salt is a field you can read on every recorded row, because the salt appears by name in the ingredient list whatever else a maker chooses to print. The parts-per-million figure, which the annex text we read does not itself require, is printed on 24 of the 26 rows anyway, and the active's level on ten of them, which makes the level a disclosure choice and never a strength rating: a blank means the figure was not published, not that it is low¹.

If your old tube was a potassium nitrate paste, which tubes match it?

If it printed 5% potassium nitrate with 1450 ppm sodium fluoride in a water-based paste, one UK row carries that fingerprint in full, and seven more agree on every field they print while leaving the level blank, so the fourth field cannot be checked.

This page compares ingredients and stated actions only, not clinical performance, based on what each brand states about its own formula. Prices and formulations may change; always check the pack. The lookup below reads each old-tube fingerprint against the recorded rows for the families this page covers, with the product names spelt as the review spells them; every row, with its source and the date it was read, is in the category review of UK sensitivity toothpastes by ingredient, and all of them were read from retailer and brand pages on the ninth or tenth of September 2026.

Two things in that table deserve a plain sentence each. A match on three fields with a blank level is the commonest result for a potassium nitrate tube, and the blank cuts both ways: a tube that prints nothing may hold the same 5% as one that does, or it may not, and nobody outside the maker can tell.

The own labels are the second. The Boots own-label sensitive paste matches Sensodyne Daily Care Original on every field either listing prints: potassium nitrate, no level, sodium fluoride at 1450 ppm, water. Their full lists share ten ingredients and part company on the rest, with a different foaming agent, a different thickener and different colours, so the match is on paper and does not make them one paste. That points some readers towards one of the least expensive tubes on the recorded shelf, and for a reader whose only aim is the old fingerprint back it is where the lookup lands. The page on the Boots and Superdrug shelf reads those own labels in full.

If it was a stannous fluoride or bioactive-glass paste, which tubes match it?

For the anhydrous stannous fingerprint, three rows under two brand names match on all four printed fields, and for the 5% bioactive-glass fingerprint one row does.

The stannous family is where the water field earns its place. The three anhydrous rows print 0.454% stannous fluoride; the two Oral-B rows print no percentage and instead declare, in their hazards block, 1100 ppm of fluoride from stannous fluoride and 350 ppm from sodium fluoride. By molecular weight, 0.454% stannous fluoride carries about 1100 ppm of fluoride, so on paper those five tubes hold the same amount of the active and the same 1450 ppm of fluoride overall, and what divides them is that the Oral-B pair lists water and the other three do not. Same active, same dose on paper, two bases: a reader moving from one group to the other has changed the water field and, with it, the base chemistry no pack describes. Colgate Sensitive & Gum Strength also lists water and prints stannous and sodium fluoride to 1450 ppm between them without the split, so it agrees with the Oral-B pair on everything except a figure it leaves out.

The bioactive-glass rows all belong to one brand. The 5% figure is printed on Sensodyne Clinical Repair Active White, the two Repair & Protect listings name the same glass with no level and publish identical ingredient lists, and all three are anhydrous with 1450 ppm sodium fluoride. No row from another maker in the review lists calcium sodium phosphosilicate. The two nearest glass-type actives each differ on at least two fields: one binds 530 ppm of fluoride into its own glass in an anhydrous paste, and the other pairs a calcium phosphosilicate with sodium monofluorophosphate in a water base. For a glass user leaving the brand, then, the recorded shelf holds no like-for-like, and the real decision is between another occluding active and a nerve active the glass tubes never carried.

What if your old tube carried an active almost nobody else uses?

Then the realistic answer is a match inside one maker's range, or no match at all. Arginine at 8% appears on three recorded rows, all Colgate, all with sodium monofluorophosphate at 1450 ppm in a water base: two 100 ml listings that publish identical ingredient lists, and a 75 ml listing whose supporting ingredients differ. No arginine row from another maker was recorded.

One more listing belongs in this paragraph and not in the table. The Boots page for Colgate Sensitive Instant Relief Enamel Repair names an arginine technology in its product description, while the ingredient panel on the same page lists no arginine. The listing does not agree with itself, and a page read from outside cannot say which half describes the tube in the box, so read the pack.

Potassium citrate sits on two rows. Spotlight Sensitivity + Rebuilding Pro pairs it with hydroxyapatite and 1450 ppm sodium fluoride in a water base and prints no level for either active; Ordo Complete Care Toothpaste carries potassium citrate with zinc citrate and the same fluoride, and no hydroxyapatite. The two disagree on the active field, so neither is a like-for-like for the other, and a reader of either is choosing between keeping the potassium and keeping the hydroxyapatite.

Hydroxyapatite has its own troubleshooting page for hydroxyapatite toothpaste users, which reads the seventeen recorded hydroxyapatite tubes by what else is in them. Four of those tubes print a level and four keep fluoride, and a like-for-like search there runs into the same blank column as it does here.

Does the fluoride salt matter when the active is the same?

It can, and the one comparison that held potassium nitrate identical in both pastes came out against sodium monofluorophosphate. In an examiner-blind randomised trial published in 2000, whose record carries no funding statement, both pastes held 5% potassium nitrate: one delivered its fluoride as 0.454% stannous fluoride in a silica base, the other as 0.76% sodium monofluorophosphate in a dicalcium phosphate base⁸. At four weeks and again at eight, the trial found that the stannous fluoride paste had reduced tactile and air-blast sensitivity significantly more, among the 101 adults who completed, and its funding is not stated⁸.

Sodium monofluorophosphate is the salt S3 uses. The choice was forced by the rest of the formula: S3 carries its 1450 ppm of fluoride in that form because this salt leaves the calcium of hydroxyapatite in the tube alone.

For the lookup, that is reason enough to treat the salt as a field and not a footnote. Two tubes that agree on the active and differ on the fluoride salt are not a match, even when both print 1450 ppm.

Is S3 an equivalent to the tube you had?

No, for any tube on this page, and a reader who wants their old paste back should not buy S3 as a substitute, because against any potassium nitrate tube it would replace, it changes the fluoride salt and adds two actives.

Field by field, from its own list. The active field is where the difference starts: S3 lists potassium nitrate at 5%, potassium chloride as a second potassium source, and two hydroxyapatites beside them. The level field is printed, with a caveat that belongs to us: 10% nano-hydroxyapatite and 5% biomimetic hydroxyapatite are inclusion levels of the ingredients as supplied, the active hydroxyapatite content is lower, and the product page recorded for the category review prints the inclusion figures with no separate figure for that lower content. So S3's own tube cannot be fingerprinted to the last detail of its mineral content from the pack either, which is the same limit this page sets on everyone else's blank column. The fluoride field is sodium monofluorophosphate at 1450 ppm, where ten of the twelve potassium nitrate rows use sodium fluoride. The water field is the one S3 shares with most of them. Its water base is what allows potassium nitrate and hydroxyapatite to share one tube, which an anhydrous formula built around bioactive glass cannot do.

The nearest recorded row by mechanism is not a potassium nitrate tube. Spotlight Sensitivity + Rebuilding Pro carries a potassium salt, hydroxyapatite and fluoride in a water base, and it differs from S3's list on three fields: citrate in place of nitrate, sodium fluoride in place of monofluorophosphate, and no printed levels.

Where S3 does fit is the reader for whom a match is not the answer, because the tube being replaced carried one mechanism and had stopped helping before its formula changed. Hydroxyapatite's job is occlusion and potassium's is desensitising; since neither can do the other's, a formula aimed at sensitivity has to carry both.

When there is no equivalent, how should you choose?

Choose the mechanism first and the brand second, because the name on the front of a tube is the least reliable field on this page. One market-leading name covers potassium nitrate, stannous fluoride and bioactive-glass tubes, so a reader loyal to the name can change mechanism without noticing, and a reader who leaves it for an own label can keep exactly the active they had. The page that decodes the market leader's range variant by variant sets out which is which. Asked on its UK FAQ page how to choose between Sensodyne and Pronamel, the brand answers: "To find the right toothpaste for you, discuss it with your dentist who can advise what suits you best".

If you are choosing a family, the most useful thing the newest pooled evidence offers is its certainty ratings rather than its league table. A 2026 systematic review and network meta-analysis of 93 randomised trials rated stannous fluoride as the one class with high-certainty evidence on the cold-air score against a benchmark fluoride paste at two weeks, nano-hydroxyapatite as moderate on the strength of two studies, and arginine, potassium and bioactive glass as low⁹. Stannous fluoride is not on S3's list, and the review's authors put it forward, with arginine, as first-line self-care⁹. The guide to alternatives by active ingredient sets out the estimates family by family, and the Journal's piece on how sensitive toothpastes work and why yours might not be working covers the mechanisms first.

Nobody has tested the move this page is about. The searches run for this page turned up no trial that moved people between two toothpastes carrying the same active. The nearest design on record is a double-blind randomised switch-over trial whose record carries no funding statement, in which 121 adults used an 8% arginine paste or an 8% strontium acetate paste for eight weeks and then swapped to the other: those moving from strontium acetate to arginine improved further on touch and air-blast scores two and eight weeks after the swap, and those moving the other way did not¹⁰. Both swaps changed the active, so it cannot speak to a like-for-like move. What it does record is one direction in which changing mechanism after eight weeks on the first paste was followed by further improvement.

Whatever you choose, borrow the clock that trials use. The guidelines for trials in this condition, drawn up by a consensus group in 1997, recommend eight weeks for most studies with negative and benchmark controls¹¹. A bathroom has no control group, which is why the page on how long to give a new sensitivity toothpaste spells out what a person can and cannot learn from their own weeks.

And before blaming the new formula, rule out the explanations that have nothing to do with it. A paste can seem to stop working at the moment its pack changes for reasons that are about the mouth and not the tube, and the pages on why a sensitivity toothpaste stops working and on sensitivity that keeps building despite a sensitive paste go through them one at a time.

When should you stop looking for a toothpaste and see a dentist?

When the pain stops behaving like sensitivity, because nothing in the lookup above is a diagnosis. The Oral Health Foundation gives four reasons to book: the pain is severe, the sensitivity lasts more than a few weeks, one tooth only is affected, or the pain comes on suddenly, and any of them can be a sign of decay, a cracked tooth, gum problems or infection¹². Its sensitive-teeth page thanks Oral-B for the educational grant that supports it, which is worth knowing when you read its advice on toothpaste¹². For toothache the NHS draws its line at two days, and sooner if painkillers do not shift it, if it comes with a high temperature, pain on biting, red gums or a bad taste, or if the cheek or jaw swells; swelling around the eye or in the neck, or swelling that makes breathing, swallowing or speaking difficult, is a reason to go to A&E¹³. A changed formula does not produce any of those, and a matching tube will not treat them.

Frequently asked questions

Does S3 contain the same active as my old potassium nitrate toothpaste?

Yes for the potassium nitrate, which S3 lists at 5%, and no for the formula. Beside it sit potassium chloride and two hydroxyapatites, printed as 10% nano-hydroxyapatite and 5% biomimetic hydroxyapatite on an as-supplied inclusion basis with a lower active hydroxyapatite content, and its fluoride is 1450 ppm sodium monofluorophosphate where most potassium nitrate tubes use sodium fluoride. Like most potassium nitrate tubes it is water-based. It keeps your old tube's nerve active and changes the rest of the fingerprint, so treat it as a new formula and judge it as one.

Is a pharmacy or supermarket own-label sensitive toothpaste the same as the branded one?

Not the same, though sometimes a match on paper. The Boots own label agrees with Sensodyne Daily Care Original on the active, the blank level, the fluoride and the water base, while their complete lists differ in the ingredients around those four. Superdrug's own label lists every ingredient on the Boots own label's list plus one more colour, and prints no fluoride strength, so its fourth field cannot be checked. The supermarket own labels could not be read when the review was run, so this page says nothing about them.

Should I just switch to the same brand's other sensitive variant?

Read its list first, because a sister variant can be a different mechanism. Under one market-leading name the recorded tubes carry potassium nitrate, stannous fluoride or bioactive glass depending on the variant. If the variant you pick lists the same active as your old tube, it can be a match; if it lists another, you have changed treatment and kept the name.

Has anyone tested whether switching to a paste with the same active brings the relief back?

None of the trials this page's searches turned up has done it. A PubMed search in September 2026 for desensitising toothpaste trials with switch-over or crossover designs returned 13 records, and the one switch-over trial among them moved people between two different actives, arginine and strontium acetate, in a record that carries no funding statement¹⁰. A second search, for reformulated or new formulations, returned four records, one of which compared a reformulated paste with its original³. So a like-for-like replacement after a reformulation is a move nobody has yet put to a trial.

What if I no longer have the old tube?

Use any record of it you can find: a photograph of the back of the pack, the retailer listing you reordered from, or an order confirmation naming the exact variant. The page on whether the market leader has changed its formula shows how to set an old list beside a new one. Copy down the four fields this page uses, and remember that the category review records what each listing printed on the day it was read, the ninth or tenth of September 2026, which makes it a snapshot and not a history.