Are whitening strips (Crest Whitestrips®) harmful to your teeth? | Are they safe to use?

- Does using strips damage tooth enamel? | Study findings about whitener safety. | What happens if you swallow a strip? | Disadvantages and inherent problems associated with using whitening strips.

If you're concerned about safety considerations associated with using teeth-whitening strips, this page should help to put your mind at ease. For specific details, select from the following categories:


This page also explains the inherent disadvantages associated with using this technique.

Is using whitening strips safe for your teeth?

When used as directed, strip products (like Crest Whitestrips®) have not been shown to damage teeth.

  • Clinical research and trials have not identified any significant effects associated with using them (even when used outside of normal recommendations, discussed below).
  • Their roughly two decades of use by the general public has not demonstrated any serious long-term or irreversible adverse effects to teeth, gums or tooth nerve tissue.



That's not to say that using strips can't cause side effects, because they do for some people. But that's a separate issue (follow the link for details and remedies).

Research studies that have evaluated the possible harmful effects of whitening strips on teeth.

Picture of a Crest Whitestrip®.

A Crest Whitestrip®.

Study - Duschner (2006)
Title: Effects of hydrogen peroxide bleaching strips on tooth surface color, surface microhardness, surface and subsurface ultrastructure, and microchemical (Raman spectroscopic) composition.
This study evaluated the use of a 6% hydrogen peroxide product (Crest Whitestrips®) at twice the recommended exposure.

The tooth samples were: 1) Evaluated for changes in enamel surface hardness. 2) Evaluated for structural changes using an electron microscope. 3) Tested for changes in their chemical composition. No deleterious effects were identified.

Study - Gotz (2007)

Title: Effects of elevated hydrogen peroxide 'strip' bleaching on surface and subsurface enamel including subsurface histomorphology, micro-chemical composition and fluorescence changes.

This study investigated how 13 and 15% hydrogen peroxide strips affected tooth enamel. (At the time, the product used was a prototype. The exposure time used was 28 hours, which is roughly 3 times the level recommended for this type of strip when it finally came to market.)

The same testing carried out with the Duschner paper above was performed for this study too. No deleterious effects were found.

Study - White (2003)

Title: Effects of Crest Whitestrips bleaching on surface morphology and fracture susceptibility of teeth in vitro.

This study examined the effects of using 5.3% and 6.5% Whitestrips® hydrogen peroxide gels on tooth enamel using exposure times up to 5 times longer than normally recommended (14 vs. 70 total hours).

The samples were evaluated for changes in surface morphology, microhardness and fracture susceptibility. No changes or deleterious effects were identified, even under these excessive conditions.

Study - White (2002)

Title: Peroxide interactions with hard tissues: Effects on surface hardness and surface/subsurface ultrastructural properties.

This previous study by White (2002) also evaluated 5.3% and 6.5% H2O2 Whitestrips® whiteners, at exposure times ranging from 14 to 70 hours (5 times the normal treatment time).

After treatment, no significant changes were found in the microhardness of tooth enamel. Laser scanning microscope evaluation failed to detect changes in enamel crystalline architecture.

Section references - Duschner, Gotz, White, White

A picture of a box of Crest Whitestrips® Vivid.

A standard "introductory" Whitestrips® product.

Interpreting the above findings in light of today's products.

Since the time frame when the above studies were performed, Crest® has6 discontinued it's introductory 6% strip (Whitestrips® Classic) and has generally replaced it with 10% hydrogen peroxide products.
Twice the concentration. Half the treatment time.
While their concentration is almost double, the treatment time recommended for the 10% strips is half as much (once-a-day vs. twice-a-day for the 6% strips). The net result is a similar total exposure to the peroxide whitener when either type of product is used.

That means the 6% studies mentioned above are still valid in reference to today's products. And this is confirmed by the Gotz study that found that using a higher concentration strip poses no special concerns for tooth safety.

Whitestrips® health and safety concerns.

Using strips provides a consistent, controlled dosing of whitener.

As far as teeth bleaching methods go, whitening strips are unique in the fact that the user receives a very precise exposure to the whitening agent.

That's because it's applied to the strip by the manufacturer when they are made. In comparison, when a tray system or whitening pen is used, the user often ends up applying significantly more than is recommended.

And in light of the unsupervised nature of the use of over-the-counter products and potential safety concerns, this is a comforting feature.

An example of whitener dosing - Strips vs. trays.

It's been estimated that a session utilizing a 6% hydrogen peroxide whitening strip (which is comparable to how today's 10% strips are used) involves the use of one-half to one-fifth as much total peroxide as a comparable treatment utilizing a tray-based system with a 10% carbamide peroxide bleaching gel. (FYI: Both systems should provide similar whitening results.)

Safety concerns associated with peroxide whiteners.

We already have a page that details the safety concerns associated with the use of peroxide tooth whiteners.

It primarily discusses this issue from a standpoint of using a tray-bleaching technique. But since the whitening science for both methods is the same, that information applies to the use of strips too.

Remember, strips deliver a lower dose.

When reading that information, keep in mind that your dosing of peroxide when using strips can be expected to be substantially less than when trays are used, which helps to make your experience that much safer.

Our take on the safety of using whitening strips.

We would have little concern about safety issues associated with the use of strips technique as a method for whitening teeth. That, of course, implies that the product is used within its manufacturer's guidelines, or if at any level beyond that, under the supervision of a dentist.

Whitening product abuse.

We're familiar with a class of end-users who adopt an attitude that using whitening strips is totally benign, and therefore use them at their whim, for indefinite periods of time (either continuous or intermittently), and characteristically under circumstances where the treatments performed have essentially no potential benefit toward providing added whitening effect.

Why the indiscriminate use of peroxide whiteners is never appropriate.

For people contemplating this type of behavior, we'll point out the following study.

Study - Del Rel Garcia (2019)

Title: In vivo evaluation of the genotoxicity and oxidative damage in individuals exposed to 10% hydrogen peroxide whitening strips.

In a nutshell, this study looked for evidence that using whitening strips coated with a 10% hydrogen peroxide whitener (which nowadays is the standard "introductory" strip product) causes DNA damage in the cells of soft tissues of the mouth (cheek linings, gum tissue).

As findings, the authors stated that exposure to the strips "increased genotoxic and oxidative damage" in the tissue cells (caused DNA damage) of study subjects. And specifically stated, "Therefore, self-application of bleaching agents should be handled carefully since it could be a risk to human health."

Section references - Del Rel Garcia

So if you think that the indiscriminate use of whitening strips (or really any at-home bleaching method) is unquestionably benign and without any potential concern, we would disagree and would base that opinion on the findings of this study.

Additional takes on this study's findings.

Having stated the above, here are some replies we would have to possible reader questions.

Do we think this single study is the end-all authority on this subject? - No.

Is there anything about these findings especially unique to using whitening strips? - No. One would assume that similar findings would be found for any at-home bleaching method that creates a similar exposure of hydrogen peroxide.

Does this study indicate that using whitening strips is dangerous? - For us, it would come down to a risk/reward calculation. In cases where whitening results can be expected (the case for most people when initially using this type of product), we personally would perform treatments and accept the associated risks.

But in cases where the person's activities could be categorized as whitener abuse (like described above), we think this study points out why that habit makes such an inappropriate choice.

Is it harmful to swallow a whitening strip?

The consequences of this type of event occurring are usually just minor and transient in nature. We explain why, and what factors are the major determinants, on our "What happens if you've swallowed a whitening strip?" page.

Is it harmful to use an expired WhiteStrips® kit?

The primary problem associated with using expired strips is generally one of ineffectiveness as opposed to safety.

The expectation would be that the concentration of the hydrogen peroxide in its whitener (its active ingredient) would be degraded or depleted, thus rendering the strips less effective.

Storing unused kits or strips in your refrigerator (not freezer) is a good way of extending their marked shelf life.

Are whitening strips safe for dental work?

Yes, strips can be considered safe to use with existing dental work, in the sense that the chemical process involved (peroxide teeth whitening) won't damage them. But beyond that specific point, there are some issues of which you should be aware.

Whitening strips will not lighten existing dental restorations.
  • As a general rule, using strips will not lighten white dental fillings, veneers, dental crowns (caps) or dentures.
  • If you do perform treatments, because your natural teeth will respond and your restorations won't, you may actually make the appearance of your smile worse (less uniform in color).


This is an important issue to keep in mind because if this complication occurs, the only solution will be to replace your existing dental work (which is often a very expensive proposition).

Dental treatment plan considerations.

In the case that you have teeth or existing restorations that require attention, you must discuss with your dentist how your whitening plans should fit in with your overall treatment plan.

Performing treatments could aggravate compromised teeth, or teeth with compromised restorations. And some types of dental restorations should only be placed after a post-whitening waiting period.

There's more to know.

If any of these issues seem to apply to your situation, to be on the safe side you should educate yourself further. We discuss concerns associated with dental restorations and peroxide teeth whitening on this page.

General disadvantages of using teeth whitening strips.

A) They can't be used to whiten side or back teeth.

Teeth whitening strips can only be used to whiten front teeth.

Whitening strips don't always whiten all of your teeth that show.

One disadvantage of using strips as a bleaching method is that they can only be used to treat your front teeth.
This issue isn't likely a problem for most people. But for those who have a really broad smile, the fact that their front teeth have been whitened and their back ones have not may create a color mismatch that is obvious.

(This issue is not a concern with tray whitening technique.)

What can you expect?

Most people will find that their whitening strips reach at least from eyetooth to eyetooth. But how much further beyond, and how much further beyond would be ideal, will vary.

Some strips are designed with this problem in mind. For example, Crest Whitestrips® Professional Effects has a longer strip for lower teeth. Competing brands frequently mention a longer length as one of their selling points.

B) Crooked teeth may not whiten uniformly.

To be effective, a whitening strip must lie in contact with a tooth's surface. And in the case where your teeth have an especially irregular alignment (a prominent tooth or two, rotated teeth, etc...), it may not be possible to create the needed tooth-to-strip contact for each one.

If not, individual teeth or tooth portions will have a different level of exposure to the strip's whitener, which can result in uneven whitening.

C) Handling whitening strips can be difficult.

A general disadvantage of performing whitening treatments using strips is that they can be tedious to deal with.

  • Strips are sticky and relatively flimsy and therefore can be difficult to manipulate and easy to spoil.
  • When applying them, you must touch them. This may cause skin irritation. Or you may inadvertently transfer whitener to other objects, which may mar or damage them.


  • During treatments, strips need to be monitored to make sure that they're still in place. (Although, with the newer, more adherent styles of strips this has become less of an issue.)


As compared to tray whitening technique ...

Some people consider using whitening strips to be more of a struggle than using bleaching trays.

When quizzing 24 subjects, a study by Da Costa found that more than 3/4ths preferred tray whitening to the use of whitening strips.

Section references - Da Costa

Different strips have different characteristics.

It's both a strip's shape, and the tackiness of its whitener, that helps to hold it in place.

And the specific strip design and whitener formulation used with different products do vary. And this can make some easier to wear than others.

If you've used strips in the past (especially the distant past) and had difficulties, the general trend nowadays (with newer versions of products) seems to be the use of a much tackier, more adhesive-like, whitener (see link above). So, you may find trying again may be a better experience.

D) Other at-home approaches may be more effective.

Published research has found whitening strips to be a very effective at-home whitening method. But we would anticipate that most dentists would consider tray whitening to have a slight edge on this issue. But when you factor in convenience, strips frequently make the obvious first choice.

E) The whitening effect will fade.

This point isn't a disadvantage that's unique to just strips. The whitening effect created by any and all bleaching methods will tend to fade over time.

This is usually more of an inconvenience than a big problem. We discuss touch-up frequencies and options that are common with whitening strips here.

F) There's no professional supervision.

Once again, this isn't a criticism that's unique to just whitening strips. All over-the-counter systems suffer from the disadvantage that the user's dentist frequently isn't consulted about their bleaching activities.

But just because you can perform treatments entirely on your own doesn't mean that you have to or should. It's always the right choice to discuss your whitening plans with your dentist. And ideally, before you begin. Their knowledge can help to improve both the effectiveness and safety of your efforts.


 Page references sources: 

Da Costa J. Comparison of Two At-home Whitening Products of Similar Peroxide Concentration and Different Delivery Methods.

Del Real Garcia JF, et al. In vivo evaluation of the genotoxicity and oxidative damage in individuals exposed to 10% hydrogen peroxide whitening strips.

Duschner H, et al. Effects of hydrogen peroxide bleaching strips on tooth surface color, surface microhardness, surface and subsurface ultrastructure, and microchemical (Raman spectroscopic) composition.

Gotz H, et al. Effects of elevated hydrogen peroxide 'strip' bleaching on surface and subsurface enamel including subsurface histomorphology, micro-chemical composition and fluorescence changes.

White DJ, et al. Effects of Crest Whitestrips bleaching on surface morphology and fracture susceptibility of teeth in vitro.

White DJ, et al. Peroxide interactions with hard tissues: Effects on surface hardness and surface/subsurface ultrastructural properties.

All reference sources for topic Teeth Whitening Strips.