Hydrogen Peroxide On Teeth: UK Limits And Risks

Hydrogen peroxide, and carbamide peroxide which releases it, are the bleaching agents Bupa gives as examples for professional teeth whitening, and in the UK the law decides how much of either can go on your teeth and through whom. A whitening product sold straight to you can contain or release no more than 0.1% hydrogen peroxide. Between 0.1% and 6% it can only be sold to dental practitioners, the first use in each course is carried out by them, or under their direct supervision where an equivalent level of safety is ensured, and it must not be used on anyone under 18. Above 6% is prohibited for whitening. For whitening at a dentist, the NHS lists side effects including sensitivity and sore gums that may last a short time, Bupa says sensitivity should settle after a couple of days, and both name your dentist as the person to tell. A home-made peroxide mix sits outside every one of those safeguards.

What hydrogen peroxide does to a tooth

Bupa's teeth whitening page, clinically reviewed by Dr Gurmandeep Sond and Dr Emma Ajimoko of Bupa Dental Care and last reviewed on 30 June 2025, describes the mechanism in three sentences: "Teeth whitening works by using a gel that contains bleaching agents like hydrogen peroxide or carbamide peroxide. These agents break down and release oxygen molecules that penetrate the hard outer layer of your teeth (enamel). Once inside, they react with other teeth-staining molecules to lighten them."

Two things follow from that. Peroxide is not scrubbing a stain off the surface. It reacts with the coloured molecules, which is why it can change the shade of a tooth rather than only clean it. And carbamide peroxide is not a separate chemical in the eyes of the law. The UK entry covers "Hydrogen peroxide and other compounds or mixtures that release hydrogen peroxide, including carbamide peroxide and zinc peroxide", so a gel that lists carbamide peroxide is measured by the hydrogen peroxide it releases.

The UK limits, in the law's own words

The rules sit in entry 12 of Annex III to Regulation (EC) No 1223/2009 on cosmetic products, as retained in Great Britain and kept on legislation.gov.uk with the amendments made since the UK left the EU. The 6% tier entered UK law through The Cosmetic Products (Safety) (Amendment) Regulations 2012, made on 2 September 2012 and in force from 31 October 2012. Their explanatory note puts the change in one sentence: "This increases the percentage of hydrogen peroxide allowed in tooth whitening or bleaching products to 6% subject to conditions which include first use by a dental practitioner."

The lines that matter for teeth read as follows in the 2012 regulations. Annex III carries the same figures and conditions today, written there with decimal commas.

• Sold to the public. "Oral products, including mouth rinse, tooth paste and tooth whitening or bleaching products": "≤ 0.1% of H2O2, present or released".
• Through a dentist. "Tooth whitening or bleaching products": "> 0.1% ≤ 6% of H2O2, present or released", with the condition "To be only sold to dental practitioners." The first use in each cycle is by a dental practitioner, or under their direct supervision if an equivalent level of safety is ensured, and the product is "Afterwards to be provided to the consumer to complete the cycle of use."
• Age. For that same 0.1% to 6% tier: "Not to be used on a person under 18 years of age."

Two details in those lines carry a lot of weight. "Present or released" is why carbamide peroxide is caught: the limit is on the hydrogen peroxide a product gives off, whatever name is on the label. And the under 18 condition is part of the law itself, not a guideline.

The General Dental Council's position statement on tooth whitening, dated 11 July 2016, states the age rule with its one exception: products containing or releasing between 0.1% and 6% hydrogen peroxide "cannot be used on any person under 18 years of age except where such use is intended wholly for the purpose of treating or preventing disease." On the top of the scale it is just as direct: "Concentrations exceeding 6% of hydrogen peroxide present or released in oral products, including tooth whitening or bleaching products, remain prohibited unless wholly for the purpose of the treatment or prevention of disease."

That is the core of the law on peroxide for teeth. Who may whiten somebody else's teeth, imported kits and how to read a box before you buy are covered in our guide to whether teeth whitening is legal, so they are not repeated here.

What the 0.1% limit means for a kit you buy yourself

Bupa's page makes the practical point plainly: "In the UK, shop-bought whitening kits are legally only allowed to contain 0.1% hydrogen peroxide. But these low levels don't achieve the same results as professional whitening. Whitening treatments carried out by a dentist can contain up to 6% of hydrogen peroxide."

The GDC statement covers the other side of the same line. Products containing or releasing less than 0.1% of hydrogen peroxide, including tooth whitening or bleaching products, it says, "will continue to be freely available on the market." So 0.1% is the line for open sale, and it is also why a peroxide kit bought off a UK shelf works at a small fraction of the strength a dentist can use.

Why the stronger gels only come through a dentist

The GDC statement sets out how products between 0.1% and 6% should be used, and the list reads like a description of what a dental appointment adds:

• "an appropriate clinical examination is to be carried out in order to ensure that there are no risk factors or any other oral pathology concerns;"
• "exposure to these products should be limited to ensure that the products are only used as intended in terms of frequency and duration of application;"
• "the products should not be directly available to the consumer, only through a dentist, dental hygienist, dental therapist or clinical dental technician."

The NHS teeth whitening page describes the same steps from the patient's side: "The dentist should check your teeth and gums are healthy before you try teeth whitening, to make sure the treatment's right for you." For laser whitening at a dental surgery, it adds that before treatment "a soft shield or paste is used to protect your gums". And if somebody is offering to whiten your teeth for you, the NHS points to one check: "You can check if someone is a registered dental professional on the General Dental Council website."

Sensitivity and the other side effects of peroxide whitening

Neither the NHS nor Bupa presents whitening at a dentist as free of side effects. The NHS page, last reviewed on 19 August 2025, says "Teeth whitening by a dental professional uses strong chemicals which may cause side effects." It lists three:

• "teeth becoming sensitive to cold or sweet food and drink"
• "sore gums or throat"
• "white patches on your gums"

Protection reduces the risk rather than ruling it out: "Your dentist should use a soft shield or paste to protect your gums during treatment, but you may still get side effects for a short time. Talk to your dentist if you have any side effects that bother you."

Bupa, whose page gives hydrogen peroxide and carbamide peroxide as examples of the bleaching agents in the gel, puts sensitivity in its aftercare advice: "Your teeth might feel more sensitive after tooth whitening treatment. This should settle down after a couple of days, but if it doesn't, let your dentist know."

Put together, that is what the two UK sources describe for whitening at a dentist, where, as Bupa says, treatments can contain up to 6% hydrogen peroxide: teeth that react to cold or sweet things, possible soreness or white patches on the gums, expected to pass within a short time, and a reason to talk to your dentist if they bother you or do not settle. If sensitivity is what has kept you away from whitening, there is a separate page on strips for sensitive teeth.

Enamel is a separate question, and it needs a study rather than a slogan. The one laboratory comparison we can cite, with the limits its authors state, is set out in our post on whether whitening strips harm enamel.

Why do-it-yourself peroxide is a bad idea

Put the law and the GDC conditions side by side and the problem with a home-made peroxide mix is plain. Peroxide above 0.1% is only supplied through a dentist, after an examination, with exposure limited in how often and for how long, and, in the NHS's description, with the gums protected. A mix put together at home has none of that. Its strength on the tooth is unknown, no examination has looked for the "risk factors or any other oral pathology concerns" the GDC names, and nothing is shielding the gums that the NHS says a dentist should protect during treatment.

And the safeguards do not remove the side effects even when a dentist is in charge. The NHS is clear that they may still follow for a short time. Starting without any of the safeguards is not a cheaper route to the same result. It is the same chemistry with the checks taken away.

Whether a particular toothpaste, mouthwash or rinse suits you is a question for your dentist or pharmacist, and it is not one this post answers. If you are thinking about putting a peroxide product on your teeth that was not sold to you for that job, that is a conversation to have with a dentist before anything goes near your teeth.

Where PAP sits in all this

Entry 12 is a rule about hydrogen peroxide, present or released. PAP, short for phthalimidoperoxycaproic acid, is not hydrogen peroxide and does not release it, so that entry does not govern it. It is still a regulated cosmetic product and still needs its safety assessment. It simply is not caught by the peroxide ceiling.

PAP is an oxidising agent. It is peroxide free, and it still works on the coloured compounds inside the tooth, just by a gentler route than peroxide takes. The chemistry is set out properly in what PAP teeth whitening is, and the two chemistries are put side by side in how PAP and peroxide compare.

Peroxide is also part of how Pure Glow started. Our founder, Daniel Smith, came to whitening as a customer, and peroxide strips gave him bad sensitivity. The brand's peroxide-free whitening strips are what he went on to create, with hydroxyapatite and xylitol in the same formula.

The claim on the box is a ceiling rather than a promise: up to 6 shades whiter in 14 days, depending on where you start, from a 14-day box of PAP strips worn for a minimum of 30 minutes each day. Every ingredient is listed on our full ingredients page.

Frequently asked questions

Is peroxide safe for teeth?
Hydrogen peroxide, within the UK limits and used the way the law sets out, is legal and in use. Products sold to the public can contain or release no more than 0.1%. Stronger gels, up to 6%, are supplied only through a dentist, after an examination, and even there the NHS lists side effects including sensitivity and sore gums, while Bupa says sensitivity should settle after a couple of days. A home-made mix has none of those safeguards.

How much hydrogen peroxide is allowed in teeth whitening in the UK?
Up to 0.1%, present or released, in products sold to the public. More than 0.1% and up to 6% only through a dental practitioner, with the first use in each cycle done by them, or under their direct supervision if an equivalent level of safety is ensured. The GDC says concentrations above 6% remain prohibited unless wholly for the treatment or prevention of disease.

Does carbamide peroxide count?
Yes. The law covers compounds and mixtures that release hydrogen peroxide and names carbamide peroxide among them, so the limits apply to the hydrogen peroxide it releases.

Can you use peroxide whitening if you are under 18?
Not in the 0.1% to 6% range. The law says those products are "Not to be used on a person under 18 years of age." The GDC notes the one exception, use intended wholly for treating or preventing disease.

Does hydrogen peroxide make teeth sensitive?
It can. The NHS lists teeth becoming sensitive to cold or sweet food and drink among the side effects of whitening by a dental professional, and Bupa says teeth might feel more sensitive after treatment and that this should settle down after a couple of days. If it does not settle, Bupa says to let your dentist know, and the NHS says to talk to your dentist about any side effects that bother you.

Is PAP a peroxide?
Not in the sense the law means. Its chemical name contains "peroxy", but PAP is not hydrogen peroxide and does not release it, which is why the 0.1% peroxide ceiling does not govern it. It is still an oxidising agent that works on the coloured compounds inside the tooth.

Does the under 18 rule apply to Pure Glow?
That condition belongs to the peroxide entry, and Pure Glow is peroxide free. What our box says is that the strips are not suitable for children under 12.

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Related reading:

• Why whitening strips can hurt
• Whether non-peroxide whitening works
• Crest Whitestrips in the UK
• Strips versus dentist whitening

Sources:

• Regulation (EC) No 1223/2009 on cosmetic products, Annex III, entry 12 (hydrogen peroxide), as retained in Great Britain. legislation.gov.uk
• The Cosmetic Products (Safety) (Amendment) Regulations 2012, SI 2012/2263, made 2 September 2012. legislation.gov.uk
• General Dental Council, tooth whitening position statement, 11 July 2016. gdc-uk.org
• NHS, Teeth whitening, last reviewed 19 August 2025. nhs.uk
• Bupa Dental Care, Teeth whitening, clinically reviewed by Dr Gurmandeep Sond, former Clinical Development Manager at Bupa Dental Care, and Dr Emma Ajimoko, Head of Clinical Policy and Standards at Bupa Dental Care, last reviewed 30 June 2025. bupa.co.uk