Toothpaste ingredient decoder

A toothpaste box is mostly marketing, and the ingredient list on the back is mostly chemistry, and the two rarely refer to the same thing. The decoder above reads the list and tells you what each ingredient is doing, what the fluoride strength works out at, and which four things are worth a second look. The rest of this page explains what it is doing, so you can do it without the tool.

What an ingredient list is legally required to tell you

Two rules do most of the work, and both come from the EU cosmetics regulation, with the same conventions followed in practice on American labels.

• Order means weight, down to 1%. The list “shall be established in descending order of weight of the ingredients at the time they are added to the cosmetic product”. But: “ingredients in concentrations of less than 1% may be listed in any order after those in concentrations of more than 1%”. So order is informative at the top and meaningless at the bottom, and nothing on the label marks where the switch happens.
• Nanomaterials must be declared. “All ingredients present in the form of nanomaterials shall be clearly indicated in the list of ingredients”, with the name “followed by the word ‘nano’ in brackets”. American labels carry no equivalent requirement, so Hydroxyapatite (nano) tells you something and plain hydroxyapatite on a US pack tells you nothing about particle size. There is more on that in nano vs micro hydroxyapatite.

What the list is not required to tell you is the concentration of anything. That is why the decoder reports a position rather than a percentage for most ingredients, and why the useful question about an active ingredient is usually “how near the front is it?” rather than “how much is there?”

The roles, and what each is actually for

Almost everything in a tube falls into one of about a dozen jobs. Knowing which is which collapses a frightening list into four or five decisions.

Working out the fluoride strength yourself

This is the single most useful calculation on a toothpaste box, and it is one multiplication. A label gives you either a ppm figure directly, or a percentage of a named fluoride salt. If it gives the percentage, you need the fraction of that salt which is actually fluorine:

Those three worked examples are the concentrations you will meet most often, which is why the familiar figures are 1,100 in the United States and 1,450 in Europe. For what those numbers mean in practice, England’s guidance is that fluoride toothpaste at 1,000 ppm or above prevents decay on moderate to high-certainty evidence, and that 1,350 to 1,500 ppm is advocated for higher-risk children and for everyone from seven upwards.

The four things worth flagging

1. SLS — sodium lauryl sulfate The standard foaming agent, and the standard suspect if you get recurrent mouth ulcers. Not dangerous, and worth a month’s trial of an SLS-free paste if aphthous ulcers are a pattern for you. Note that sodium lauroyl sarcosinate is a different ingredient despite the similar name.
2. Charcoal Appears as charcoal powder, activated charcoal, carbon black or CI 77266. There is no good evidence that it whitens; what it can do is lift surface stain by abrasion, and its abrasivity is almost never disclosed. Abraded enamel does not grow back, and thinner enamel shows more yellow dentine — see natural teeth whitening.
3. Hydrogen peroxide, and its percentage This is the ingredient that changes the shade of a tooth rather than cleaning something off it. Concentration matters and so does supervision; the same molecule at a professional concentration in a fitted tray is a different proposition from an unsupervised gel.
4. Potassium nitrate A sensitivity active that works by calming the nerve rather than plugging the tubule, which is why it takes about two weeks of twice-daily use to do anything. Most people who say sensitivity toothpaste did not work for them stopped inside a fortnight. See what causes sensitive teeth.

What this decoder does not do

• It does not tell you how much of anything is in the tube, because the label does not. Position gives you a floor, not a figure.
• It does not rate or rank products. There is no score, because a single number would hide exactly the trade-offs worth seeing.
• It does not know every ingredient. The list covers about 140 common ones. Anything else is marked as not recognised, or given a role inferred from the name and labelled as a guess.
• It cannot tell you a paste is safe for you specifically. Allergies, medical conditions and medications are between you and a professional.
• It does not judge abrasivity. The RDA value that would answer “is this harsh?” is not on the pack, and the grade of silica used is not disclosed.

A sensible order to read a tube in

1. Is there a fluoride source, and at what ppm? This is the biggest single difference between two toothpastes, and everything else is secondary to it.
2. What is the second ingredient? Usually the abrasive. That is what is doing the cleaning.
3. Is there an active you actually need? Sensitivity, tartar control, hydroxyapatite. If not, you are paying for it anyway.
4. Any of the four flags? SLS if you get ulcers, charcoal at all, peroxide if you did not intend to bleach, potassium nitrate if you are wondering why nothing has happened after four days.
5. Everything else is a humectant, a binder or a flavour. Which is to say: not a reason to choose one tube over another.

Our illustrations and tools are free to reuse under CC BY 4.0 — see the diagrams page.

References

1. European Union. Regulation (EC) No 1223/2009 on cosmetic products, Art. 2(1)(k) and Art. 19(1)(g). Official page, accessed 15 Sep 2026.
2. Office for Health Improvement and Disparities. Delivering better oral health: an evidence-based toolkit for prevention (chapter on fluoride). Official page, accessed 15 Sep 2026. · Funding: see ledger