Are whitening strips (Crest Whitestrips®) bad for your teeth? / Are they safe to use?

- Do strips damage tooth enamel? | Whitener safety. | Swallowing strips. | 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 of using whitening strips as a bleaching method.

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, see below).
  • Their over 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.
  • They contain the same whitening ingredient (hydrogen peroxide) as the professional whiteners dentist routinely use.


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

Research studies that have evaluated the safety of whitening strips on teeth.
  • Duschner (2006) evaluated the effects 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.

  • Gotz (2007) evaluated the effects of 13 and 15% hydrogen peroxide strips on 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.


  • White (2003) 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.

  • A 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.

[page references]

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

Since the time frame when the above studies were performed, Crest® has 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 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 that the Gotz study above confirms that using a higher concentration strip poses no special concerns for tooth safety.

Whitestrips® 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.)

a) Basic safety concerns associated with peroxide whiteners.

We already have a page that details the safety concerns associated with the use of peroxide whiteners. It tends to discuss the issue from a standpoint of 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 dosing.

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

b) Swallowing whitening strips.

One of the more unique potential problems associated with utilizing whitening strips is the situation where you have swallowed one or both of them. This risk is one reason why you should limit your oral activities when performing your treatments.

Crest Whitestrips.

Be careful not to swallow loose-fitting Whitestrips.

Toxicity calculations for swallowing strips.
In terms of systemic toxicity, the worst-case scenario would be one involving a small child.

Crest® does not recommend the use of Whitestrips® for anyone under the age of 12 (age 18 for Whitestrips Supreme®). For our calculations, we'll assume a 12-year-old weighs 90 lbs, which is about 41 kilograms.

As a source, the website of the European Union cites information that places the LD50 (median lethal dose) of hydrogen peroxide in the neighborhood of 600 mg/kg. For a 41 kg child, that would be a dosing of 24,600 mg.

The EU website also cites a Procter and Gamble study that states that 5.3% Whitestrips contain 10.6 mg of hydrogen peroxide. That type of strip really isn't commercially available, while some 10% ones are. So we'll overestimate by using a value of 25 mg per strip, 50 mg for a pair of them if swallowed.

The results.

So if our hypothetical child swallows a pair of Whitestrips®, they will get a total systemic dosing that shouldn't be more than 50 mg. That's one-fifth of one percent of the amount (24,600 mg) that's been estimated to be lethal.

Another way of saying things is that they would need to swallow on the order of 492 pairs of strips (one upper and lower) to reach a toxic systemic exposure.

What will become of the strip?

In the case where a whitening strip has simply been swallowed (no choking or coughing involved), it's most likely that it has entered your stomach. It can be expected to traverse the remainder of your digestive tract and eventually be passed uneventfully.

Are whitening strips safe for dental work?

Yes, wearing 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 just that, there are other issues of which you should be aware.

Whitening strips will not whiten existing dental restorations.
  • If you have prominent teeth that have white fillings, veneers, dental crowns (caps) or dentures, the treatments you perform can't be expected to make a change for them.
  • If you do, because your natural teeth will go ahead and lighten, you may make the overall appearance of your smile worse. (Less harmonious in terms of color match.)

This is an important issue to keep in mind because when this complication occurs the replacement of your existing dental work (and the time and expense that involves) is likely the only solution available.

Problem teeth and restorations.

In the case that you have teeth or restorations that are decayed, temporary, loose or otherwise failed you must discuss with your dentist how your whitening plans should fit in with your overall treatment plan.

Performing treatments for items in this condition could cause side effects or complications. Your whitening efforts should be coordinated (per your dentist's instructions) with the placement of any new permanent restorations.

There's more to know.

If your case seems to involve any of the above conditions, 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.

One disadvantage of using whitening strips is that they can only be used to treat your front teeth.

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

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

This issue isn't likely a problem for most people. But in the case where a person has a really broad smile, the fact that their front teeth have been whitened and their back ones have not may cause a mismatch that is obvious.

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

What can you expect?

In the vast majority of cases, a person will probably find that their whitening strips reach from at least eyetooth to eyetooth. But how much further beyond will simply depend on the overall size of their teeth.

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

B) Using whitening strips can be difficult.

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

  • They are sticky and relatively flimsy and therefore 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 damage them.
  • During treatment, strips should be monitored to make sure that they are still in place. Although, with the newer, more adherent styles of strips this has become less of an issue.


As compared to tray whitening.

For some people, using whitening strips is more of a struggle than just using bleaching trays.

When studying 24 subjects, da Costa (2012) found that more than 3/4ths preferred tray whitening to the use of whitening strips.

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 but had difficulties, the general trend nowadays (with newer versions of products) seems to be the use of a much tackier, almost adhesive-like, whitener. (See link above.)

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

Published research has found that whitening strips are 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 often do make an obvious first choice.

D) The whitening effect will fade.

This point isn't a disadvantage that's just unique to the use of strips. The whitening effect created by any and all systems will tend to fade over time. This is usually more of an inconvenience than a big problem. We discuss touch-up options using strips here.

E) 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 use.

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, before you begin. Their knowledge can help to improve both the effectiveness and safety of the process.

Can you use an expired WhiteStrips® kit?

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

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

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



Topic Menu ▶  Using Teeth Whitening Strips