Is Nano-Hydroxyapatite Safe? What Europe’s Scientists Found
You may have switched to a hydroxyapatite toothpaste to get away from fluoride, then noticed the word “nano” on the tube. And wondered if that’s the part you’re supposed to worry about.
It’s a fair question. Europe’s own scientists asked it three times.
Short answer: Yes, within limits. The EU’s scientific safety committee concluded in 2023 that nano-hydroxyapatite is safe in toothpaste at up to 10%, but only as uncoated, rod-shaped particles, and the EU wrote those conditions into law in 2024. A 2025 opinion raised the safe level to 29.5% after new data. Needle-shaped particles are out, and so are sprays. In the US, none of those particle rules apply, and hydroxyapatite isn’t an FDA-recognized anticavity ingredient at all.
It took three opinions to get to yes
First, the body doing the deciding. The SCCS (the EU’s Scientific Committee on Consumer Safety) reviews cosmetic ingredients that raise safety questions, and nano-hydroxyapatite was flagged because of its particle size.
Its 2016 opinion couldn’t reach a conclusion on toothpastes at up to 10%. The data were thin, and some research suggested the particles could be taken up locally. It also said needle-shaped nano-hydroxyapatite shouldn’t be used in cosmetics at all.
The 2021 opinion still couldn’t sign off. The committee said the data weren’t enough to exclude concerns over genotoxic potential (meaning the possibility of damaging DNA), and it kept the needle ban.
Then, in 2023, it said yes. Safe at up to 10% in toothpaste and 0.465% in mouthwash, on conditions: the particles have to be rods, with at least 95.8% of them no more than three times as long as they are wide, and they can’t be coated or surface-modified. No sprays, because there was no data on breathing it in.
And in July 2025, after a fourth submission, the committee raised the bar it had set to 29.5% in toothpaste and 10% in mouthwash. The new data showed no mutagenicity or inflammation in a cheek-cell model, negligible uptake through the lining of the mouth, and particles that dissolve rapidly in stomach acid once swallowed.
What the law says now
The 2023 opinion became law through Regulation (EU) 2024/858, which added nano-hydroxyapatite to the list of restricted cosmetic ingredients with the 10% and 0.465% limits and the same particle conditions. It also bans any use that could expose your lungs.
Non-compliant products couldn’t be placed on the EU market after February 1, 2025, or sold at all after November 1, 2025. The same regulation banned 12 other nanomaterials outright, colloidal silver among them.
The 2025 opinion’s higher limits are working their way through. A draft regulation to raise them was sent to EU member states in September 2026 and hasn’t been adopted yet.
| Quick facts | Nano-hydroxyapatite in the EU |
|---|---|
| Toothpaste limit in law | 10% (29.5% proposed, not yet adopted) |
| Mouthwash limit in law | 0.465% (10% proposed) |
| Particle shape | Rods only; needle shapes excluded |
| Coatings | Not allowed |
| Sprays | Not allowed |
| Label | “(nano)” after the ingredient name |
Nano and micro aren’t the same ingredient
In EU cosmetics law, a nanomaterial is an insoluble or biopersistent, intentionally made material between 1 and 100 nanometers in at least one dimension, and it has to be labeled with “(nano)” after its name. All the rules above cover the nano form only.
Micro-hydroxyapatite, which is larger, isn’t caught by them. That matters more than it sounds, because the best-known children’s trial didn’t use nano at all.
The trials are promising, and mostly from one company
Here’s where it gets interesting. A 2021 randomized trial followed 207 children aged three to seven for about a year, comparing a 10% microcrystalline hydroxyapatite paste against a 500 ppm fluoride paste. Cavities progressed in 72.7% of the hydroxyapatite group and 74.2% of the fluoride group, which the researchers found non-inferior, aka not meaningfully worse.
An 18-month adult trial in 2023 compared hydroxyapatite against a standard 1450 ppm fluoride paste and found 89.3% of the hydroxyapatite group had no new decay, against 87.4% for fluoride.
Now the part worth knowing. The children’s trial was funded by Dr. Kurt Wolff, a German company that sells hydroxyapatite toothpaste. Three authors of the adult trial work there. And a 2024 meta-analysis concluding hydroxyapatite works against cavities had two Wolff employees among its authors, with every author receiving Wolff travel grants. That doesn’t make the results wrong. It does mean independent replication would be welcome.
For swallowing, the 2025 SCCS opinion is the most reassuring source we found: the particles dissolve rapidly in stomach acid. That’s the main reason parents of toddlers like it, since a swallowed smear of hydroxyapatite isn’t the concern a swallowed fluoride paste can be. We cover the fluoride side of that in natural toothpaste with fluoride.
In the US, nobody checks the particle shape
The FDA regulates anticavity toothpaste as an over-the-counter drug, and its anticaries monograph lists three active ingredients: sodium fluoride, sodium monofluorophosphate and stannous fluoride. Hydroxyapatite isn’t one of them.
So a hydroxyapatite-only toothpaste in the US is sold as a cosmetic. A drug claim like preventing cavities needs either a monograph or an approved application, per the FDA, and hydroxyapatite has neither. There’s also no US rule on particle shape, coating or size, and no requirement to say “nano” on the label.
Japan went the other way and approved hydroxyapatite as an anticavity agent in 1993, though a 2019 lab study notes the early Japanese studies were mostly carried out at the manufacturer’s request.
What we’d actually do
We think nano-hydroxyapatite is a reasonable choice, and Europe’s regulators now agree, on their terms. The question for a US shopper is whether the tube you’re holding meets those terms, and the label won’t tell you.
So ask. A brand that knows its particle shape, size and whether it’s coated will say so, and some already state they meet the EU specification. If a brand can’t answer, a micro-hydroxyapatite paste sidesteps the nano question entirely. Our hydroxyapatite toothpaste picks note which form each one uses.
Frequently asked questions
Is nano-hydroxyapatite safe in toothpaste?
The EU’s scientific safety committee concluded in 2023 that it’s safe at up to 10% in toothpaste, for uncoated rod-shaped particles, and raised that to 29.5% in a 2025 opinion. Needle-shaped particles and spray products are excluded. Earlier opinions in 2016 and 2021 couldn’t reach that conclusion because the data were incomplete.
Can you swallow nano-hydroxyapatite safely?
The SCCS’s 2025 opinion found swallowed particles dissolve rapidly in stomach acid, and uptake through the lining of the mouth was negligible. That’s why hydroxyapatite is popular for young children, who swallow a lot of their toothpaste.
What’s the difference between nano and micro hydroxyapatite?
Particle size. Nano-hydroxyapatite is 1 to 100 nanometers in at least one dimension and falls under the EU’s nanomaterial rules, while micro-hydroxyapatite is larger and doesn’t. The well-known 2021 children’s trial used the micro form.
Is hydroxyapatite FDA approved?
No. The FDA’s anticavity monograph lists only sodium fluoride, sodium monofluorophosphate and stannous fluoride, so hydroxyapatite toothpaste is sold in the US as a cosmetic and can’t legally claim to prevent cavities.
Does nano-hydroxyapatite work as well as fluoride?
Randomized trials in children and adults found it non-inferior to fluoride for preventing cavities. Most of that research was funded by or involved employees of one hydroxyapatite toothpaste maker, so independent trials would strengthen the case.
Related reading
The rest of this series: does hydroxyapatite toothpaste whiten teeth and natural toothpaste with fluoride. For vetted picks, see the best hydroxyapatite toothpastes. We’ve also compared hydroxyapatite against fluoride and covered the best natural toothpastes.
Sources: Scientific Committee on Consumer Safety, opinions on hydroxyapatite (nano) from 2016, 2021, 2023 and 2025. Regulation (EU) 2024/858. Regulation (EC) 1223/2009. Paszynska et al., Scientific Reports, 2021 and Frontiers in Public Health, 2023. Pawinska et al., Journal of Dentistry, 2024. US FDA, OTC Monograph M021. Manchery et al., Dental Research Journal, 2019.
