Does purple toothpaste work? What it changes, and for how long

What purple toothpaste does: it tints, it doesn’t whiten

Purple toothpastes and serums are color correctors. We found no published study of a purple toothpaste itself: the evidence on purple products comes from serums. The one in the only clinical trial we found contains two dyes, D&C Red 33 and FD&C Blue 1. According to the trial’s authors, such dyes make teeth reflect more violet and blue light, so they look less yellow while the dyes stay bound to the thin film that coats the enamel. It is a filter on the tooth, not a change in it.

In 2024, the UK advertising regulator accepted that, in theory, purple colorants could reduce the look of yellow staining “immediately but temporarily,” and ruled one brand’s ads misleading because its evidence did not support the effects they implied.

References: [1] Pascolutti et al. · [2] ASA

Does purple toothpaste work? What the only trial measured

A 2025 systematic review, covering studies up to January 2025, found only one clinical trial of a purple product, and we found no other since. In it, 60 adults had one 30-second application, with a cotton swab, on their two upper front teeth: either the serum or the same product without its dyes. With the serum, shade moved about three steps lighter on a 29-step professional shade guide, still there at 30 and 60 minutes, and measured yellowness fell. The product without dyes changed nothing measurable.

The trial has three limits. The serum’s maker funded it, and three of its five authors work for or advise the company. Sixty minutes was the last check, with no food or drink in between. And about half of the placebo group thought their teeth had changed when the measurements showed nothing.

In an independent lab study on cow-tooth samples stained with coffee or tea, two color-corrector serums applied after brushing did no better than untreated samples, immediately, after 24 hours or after 7 days.

References: [1] Pascolutti et al. · [3] Boruga et al. · [4] Palandi et al.

Blue whitening toothpastes: more studies, mixed results

Some whitening toothpastes use a blue pigment, blue covarine, on the same principle. A trial published in 2025 (run in 2018–2019), funded by a toothpaste maker and written by its employees, found teeth less yellow right after one brushing, which raised their whiteness score; their lightness, though, dipped slightly. Two independent trials found no difference from a regular toothpaste, after one brushing or after two weeks of twice-daily use.

A meta-analysis published in late 2025 pooled five human studies. Across the three randomized trials it compared, the effect was on yellowness, not on lightness; it notes that everyday oral hygiene can remove the pigment.

References: [5] Zhang et al. · [6] Schlafer et al. · [7] Meireles et al. · [8] Jelenčiakova et al.

How long does purple toothpaste last?

Nobody knows for sure. The trial stopped at one hour, and its authors write that the time it takes to fade completely is unknown; coffee and tea were not tested. Material the brand sent the UK regulator mentions several hours, but that figure rested on three tests on two people.

None of the studies cited here shows a lasting change in tooth color, unlike the products that act on the tooth itself.

References: [1] Pascolutti et al. · [2] ASA · [9] ADA

Is purple toothpaste safe, or bad for your teeth?

In the trial, one person in 30 felt mild sensitivity that passed within minutes, and no other effect in the mouth was reported. But the trial tested one application on natural teeth without fillings or crowns; we found no study of daily use over months in people.

Is it abrasive? We found no published measurement of a purple toothpaste’s abrasiveness, and the color-corrector effect comes from its dyes, not from abrasives. Abrasiveness depends on each paste’s formula, and a toothpaste’s dentin abrasivity value (RDA) is not enough to judge enamel wear: in a Swiss lab study on cow teeth, the paste with the lowest RDA of the four tested wore enamel the most. Its authors ask that both values, for enamel and for dentin, be declared for every toothpaste.

Read the label: purple toothpastes and serums differ. The published ingredient list of the trial’s serum includes no fluoride and, according to the authors of a lab study, that serum is not meant to replace toothpaste; the blue-pigment pastes in the trial published in 2025 were fluoride toothpastes.

For sensitive teeth, for children or during pregnancy, that’s one for a dentist to look at.

References: [1] Pascolutti et al. · [5] Zhang et al. · [11] Dobler et al.

Does purple toothpaste work on crowns, veneers or fillings?

There is little to go on. The only clinical trial included natural teeth without fillings or crowns. In one lab test on a coffee-stained composite filling material, three months of simulated brushing with the serum did no better than ordinary toothpaste, though the samples lacked the saliva film the dyes bind to.

References: [1] Pascolutti et al. · [10] Yeslam et al.

Purple toothpaste before and after: how to check for yourself

Since the effect was still measurable an hour later, a photo taken right after using a purple product shows the tint along with your tooth. And the eye is easily fooled, as the placebo group showed.

To tell a tint from a lasting change, compare in the same conditions: same phone, same room, same light, before using the purple product, and days apart. A difference that shows up only right after using it most likely comes from the dye.

References: [1] Pascolutti et al.