How to make teeth whiter: what actually works

What actually whitens teeth? The methods compared

Most products sold as whitening do one of two things. Some remove surface stains left by coffee, tea, wine or tobacco, an effect the Canadian Dental Association (CDA) calls relatively minor. Others bleach: a hydrogen peroxide or carbamide peroxide gel changes the color of the tooth itself. According to the American Dental Association (ADA), toothpastes mainly remove surface stains, while most strips rely on peroxide to bleach.

How far and how fast bleaching goes depends largely on the peroxide concentration and on how the gel is delivered, the CDA adds.

References: [1] ADA (2022) · [2] CDA · [3] Devila et al. (2020) · [4] Eachempati et al. (2018) · [5] Maran et al. (2018) · [6] de Geus et al. (2025) · [7] Auschill et al. (2005) · [8] ADA MouthHealthy · [9] Kwon et al. (2015) · [11] Naidu et al. (2020) · [12] Règlement (UE) 344/2013 · [22] ADA MouthHealthy (natural whitening)

Does whitening toothpaste work?

On surface stains, yes. A 2018 review of 21 publications found that nearly all the whitening toothpastes tested reduced surface discoloration more than a regular toothpaste. A 2020 review agreed, with a difference of 1.80 shade-guide tabs on average across three studies of 1,322 people, but also found more side effects than with a regular toothpaste; in two small studies of 87 people, strips whitened more, with similar side effects. The evidence was of low to moderate quality, and in another review, most of the toothpaste and strip studies were partly or fully funded by manufacturers.

Most whitening toothpastes rely on abrasives; some add a little peroxide. Blue covarine, a pigment in some of them, works differently: it leaves a thin bluish film that changes how the color looks, not the tooth itself, and studies disagree on whether it does more than a regular toothpaste, a 2019 lab study notes.

References: [1] ADA (2022) · [3] Devila et al. (2020) · [10] Soeteman et al. (2018) · [11] Naidu et al. (2020) · [14] Vaz et al. (2019)

Do whitening strips work?

The 2018 Cochrane review of home whitening, 71 trials and 3,780 adults, found that peroxide products, from strips to trays, whitened teeth more than a placebo over short periods, 2 weeks to 6 months, with low to very low certainty, and could not say which product, concentration or schedule works best; 53 of the 54 trials that reported funding were company-funded. In a 2020 review of over-the-counter products, every strip trial had fewer than 50 participants and used 5 to 14% hydrogen peroxide.

Against trays from a dentist, a 2020 review found that strips caused less sensitivity, and that the trays’ better color change, measured by instrument, was invisible to the unaided eye.

In the EU and the UK, whitening products sold to the public may hold no more than 0.1% hydrogen peroxide, far less than the strips tested, and the UK’s Oral Health Foundation says they usually change the natural color little. In a lab study on stained cow teeth, five peroxide-free kits varied widely from brand to brand, one doing no better than a placebo, and overall changed the color less than a 16% carbamide peroxide gel. In the US, look for the active ingredient and, when it is given, its percentage.

References: [4] Eachempati et al. (2018) · [11] Naidu et al. (2020) · [12] Règlement (UE) 344/2013 · [13] GDC · [15] da Rosa et al. (2020) · [16] Oral Health Foundation · [17] Grillon et al. (2023)

Do LED whitening kits work?

An LED kit pairs a whitening gel, with or without peroxide, with a light. At the dentist, a 2018 review of 21 trials found that adding a light to the gel did not seem to improve the color change; for home kits, our LED guide goes through the little evidence there is. In the EU, the gel of a kit sold to the public may hold no more than 0.1% hydrogen peroxide.

References: [5] Maran et al. (2018) · [12] Règlement (UE) 344/2013 · [17] Grillon et al. (2023)

Whitening at the dentist: trays at home or in-office

A dentist offers two routes. With custom trays, you wear a peroxide gel at home for 1 to 2 weeks according to the UK’s Oral Health Foundation, around 2 to 6 weeks according to the NHS, the UK’s health service. In-office whitening usually takes a single visit, of about an hour according to the Oral Health Foundation. The NHS calls a kit from a dentist, or whitening at a dental surgery, the safest way to whiten teeth.

By shade guide, both end in about the same place: a 2025 review of up to 32 trials found no difference between trays and in-office whitening in shade-guide units or in the risk of sensitivity. Measured by instrument, trays came out ahead, with milder sensitivity, on low-quality evidence. In-office whitening is faster: in a 2005 trial of 39 people, 13 per method with one product each, getting six shade-guide tabs lighter took on average about 32 strip applications of 30 minutes, 7 tray sessions of 8 hours, or 3 in-office applications of 15 minutes. In the EU and the UK, strips sold to the public are now capped at 0.1%.

References: [6] de Geus et al. (2025) · [7] Auschill et al. (2005) · [8] ADA MouthHealthy · [12] Règlement (UE) 344/2013 · [13] GDC · [16] Oral Health Foundation · [18] NHS

Baking soda, charcoal, lemon: do home remedies whiten teeth?

The ADA lists acidic fruit, vinegar, charcoal and oil pulling among do-it-yourself methods and says the limited studies so far raise questions about their efficacy and safety. A 2017 review found no study of brushing with charcoal that met its criteria, and too little data to back the claims, and the ADA’s consumer site finds no reliable evidence that oil pulling or turmeric whitens teeth.

Most of the evidence on baking soda is about toothpaste: whitening toothpastes contain more silica or baking soda, notes the French oral health association UFSBD, and a 2017 review, in an industry-sponsored journal supplement on baking-soda toothpastes, found that such toothpastes remove stains. In a lab study on 120 extracted teeth, a strawberry and baking soda mix was the least effective of the whitening methods tested.

None of the sources we read tested homemade hydrogen peroxide mixtures; in the EU, whitening products that contain or release more than 0.1% hydrogen peroxide are reserved for dentists, up to 6%, and nothing stronger is allowed. As for acidity or scrubbing on your teeth, that’s one for a dentist to look at.

References: [1] ADA (2022) · [9] Kwon et al. (2015) · [12] Règlement (UE) 344/2013 · [21] Brooks et al. (2017) · [22] ADA MouthHealthy (natural whitening) · [23] UFSBD · [24] Li (2017) · [25] ADA News (2017)

Is teeth whitening safe? Sensitivity and the rules

The most common side effects of peroxide whitening are tooth sensitivity and irritation in the mouth, which the 2018 Cochrane review of home products describes as mild and transient, and more frequent at higher concentrations. The ADA says mild to moderate sensitivity can affect up to two-thirds of users early on, and with strips or trays it usually resolves by the fourth day after treatment. If it lasts, or if your teeth are sensitive to begin with, that’s one for a dentist to look at.

Rules decide who may whiten. In the EU, under Regulation (EU) No 344/2013, products that contain or release more than 0.1% and up to 6% hydrogen peroxide are sold only to dental practitioners, who perform or supervise the first use of each cycle, and are never used on anyone under 18. In the UK, only people registered with the General Dental Council may provide whitening, and products above 6% are illegal for cosmetic use. In France, the consumer authority DGCCRF says beauticians may offer products of no more than 0.1%, which clients apply themselves, but may never apply them.

Follow the product’s instructions. In 2011, French authorities warned that with peroxide whitening, exposures that are too long or too frequent risk teeth staining again faster, and that whitening should not be repeated too often.

References: [1] ADA (2022) · [4] Eachempati et al. (2018) · [12] Règlement (UE) 344/2013 · [13] GDC · [19] DGCCRF (2026) · [20] DGCCRF, DGS, Afssaps (2011)

What whitening can’t change: crowns, veneers and some colors

Only natural teeth whiten. Crowns, veneers, fillings, dentures and implants keep their color and can stand out after whitening; the CDA notes they may look darker next to whitened teeth.

Colors don’t all respond alike: yellow teeth will probably bleach well, brown teeth less so, and teeth with gray tones may not bleach at all, according to the ADA’s consumer site, which adds that whitening won’t work on discoloration caused by medications. For tetracycline, an antibiotic, the ADA’s page for dentists says the staining may lessen but can take three to four months of nightly treatment on average.

A single tooth that darkens, a sudden change, staining from a medicine, a teenager or a pregnancy: that’s one for a dentist to look at.

References: [1] ADA (2022) · [2] CDA · [8] ADA MouthHealthy · [16] Oral Health Foundation · [18] NHS

How to tell whether your teeth are really whiter

None of the sources we read can predict how many shades a given person will gain, and an advertised result is not a measurement: in 2022, the French dental council reported an investigation into a whitening kit whose peroxide level was legal but whose advertising was found misleading.

So compare like with like: the same phone, room, light and smile. Several photos taken the same way are easier to compare than a single before and after, and retouching a photo changes the photo, not your teeth.

In Enamel, the guided scan happens with the lights off, the iPhone screen as the only light; it is analyzed on the iPhone and places your shade on a 16-step scale. Each check-in scan, weekly or every two weeks, is compared with your reference scan, day 0, and a change is named only when it is clear. With strips or an LED kit, the plan follows the course on the product’s instructions; with a whitening toothpaste or nothing, it is guided brushing every day. The app’s methods guide compares toothpaste, strips, an LED kit and the dentist; Enamel sells nothing and names no brand.

References: [26] ONCD (2022)