Crest Whitestrips seem like the perfect solution for whiter teeth — they’re convenient, affordable, and more popular than ever.

But the question is: Do Crest whitestrips really work? And are they safe?

In truth, teeth whitening strips do work to make teeth look whiter and brighter. But before you try them, I want you to understand some of the risks of this teeth whitening method.

So, how do Crest Whitening Strips (by Procter & Gamble) and similar brands work?

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How Crest White Strips Work

Crest Whitestrips work by coating the teeth with a gel that contains hydrogen peroxide or carbamide peroxide. The gel is pressed against the teeth for several minutes to penetrate the enamel layer and “bleach” teeth.

These at-home whitening strips use a lower concentration of the same ingredient dentists use to whiten teeth.

Whitening strips are small pieces of an enamel-safe flexible plastic called polyethylene, a common plastic. Each strip is coated with a whitening gel and adhesive to make the strips stay put.

Ingredients in Crest Whitestrips

Crest Whitestrips ingredients include:

Water

Glycerin

Hydrogen peroxide

Polyvinylpyrrolidone (PVP)

Carbomer 956

Sodium hydroxide

Sodium saccharin

PEG-8

Acrylates copolymer

Pyrophosphate (only in Crest 3D White Whitestrips Stain Shield)

Polyethylene (the textured strip)

Hydrogen Peroxide

The European Union (EU) and Canada’s governmental body classify hydrogen peroxide, the whitening ingredient in Crest Whitestrips, as toxic or harmful when used in the mouth.

It can destroy the oral microbiome, killing off the beneficial bacteria that prevent cavity formation, gum disease, bad breath, and other conditions.

Carbamide and hydrogen peroxide are the only widely used products to whiten teeth down to the dentin layer. The most danger occurs when peroxide comes into contact with porous, sensitive gum tissue.

PVP & Carbomer

Crest Whitestrips use polyvinylpyrrolidone (PVP) to bind strips to teeth. This adhesive is safe, meaning it doesn’t bioaccumulate or disrupt hormones, like many household chemicals.

The strips also contain carbomer, another fairly safe chemical, to increase the adhesion of the gel.

These adhesives may irritate the gums and damage enamel when overused but are considered generally safe.

Sodium Hydroxide

The pH-balancing ingredient in white strips, sodium hydroxide, may be somewhat dangerous. It’s considered toxic when used inside the body.

Sodium hydroxide is a “caustic agent,” meaning it corrodes what it touches.

Sodium hydroxide is also used in hair dye. Essentially, just like you can strip your hair too much from over-dyeing it, you can do the same with teeth. (Instead of brittle hair, think: sensitive teeth.)

Sodium Saccharin

Saccharin isn’t my first choice as a sweetener — xylitol and erythritol are much better low-calorie sugar substitutes for dental health.

However, saccharin is not dangerous according to the best available scientific evidence. It was once banned because it was believed to cause bladder cancer in animals but has since been unbanned around the world.

PEG-8

In some individuals, PEG-8 may cause hives on contact with sensitive tissue like the cheeks, gums, or tongue.

The EWG also warns that PEG-8 is frequently contaminated with more dangerous chemicals like 1,4-Dioxane, a potential carcinogen.

Acrylates Copolymer

Acrylates copolymer is a polymer that holds each upper and lower strip together during use. On its own, this ingredient is considered fairly safe.

However, acrylates copolymer are often contaminated with ingredients that irritate the skin, eyes, and mouth.

Pyrophosphate

Pyrophosphate is used as the “tartar protection” in Crest 3D White Whitestrips Stain Shield. Unfortunately, multiple studies have repeatedly shown that pyrophosphate does not reduce buildup of plaque or tartar/calculus.

Are Crest Whitestrips safe?

Crest Whitestrips are safe for very occasional use. However, if you do not use them correctly or use them too often, these whitening products may cause damage to your teeth or gums.

I do not recommend patients use Crest Whitestrips more than once every 5 years.

The American Dental Association (ADA Council) has approved Crest 3D White Glamorous White Whitestrips as “safe and effective” for at-home teeth whitening. This is called a “cosmetic certification”.

A UV light, included in certain teeth whitening kits from Crest, can cause severe tooth sensitivity. This may go away within a few days to one week.

In fact, UV lights don’t seem to increase the whitening effect of peroxide beyond a week or two. There is some evidence that UV lights with peroxide may damage the pulp of your tooth, which could potentially lead to painful toothaches or the need for a root canal.

One problem — but not a safety concern — with Crest Whitestrips is that they may leave yellow or greyish spots because they don’t always adhere to surfaces of teeth evenly.

How to Use Crest Whitestrips [Step-by-Step Directions]

To use Crest Whitestrips and minimize your risk of safety concerns:

Do not brush your teeth before using white strips. Remove an upper strip and lower strip from their packets. Cut each strip to the exact height for your teeth. Peel off the plastic covering the adhesive layer. Gently place each strip on your teeth. Avoid letting strips touch the gums. Leave the strips on your teeth for the number of minutes listed on the box (usually 5 minutes or fewer). Remove the strips. Rinse your mouth with water or coconut oil. Do not brush your teeth for at least 2 hours. Repeat up to 2 times per day. Do not exceed the number of days recommended on the box.

For faster results, you can buy Crest 3D Whitestrips, the most powerful Crest Whitestrips. These are designed to stay on the teeth for 30 minutes and whiten quickly in just one use.

Some of these whitening kits come with UV lights to “speed” the process.

You should not brush your teeth before or after using whitening strips. Brushing before using white strips can increase tooth sensitivity, and brushing afterwards risks pressing the abrasive chemicals into the enamel of your teeth.

Never wear Crest Whitestrips overnight or while sleeping/napping.

Q: How long does it take to see results from Crest Whitestrips? A: Crest 3D Whitestrips will produce noticeable whitening after 3 days. Full results can be expected in 20 days of use.

Q: How many times a day should you use Crest Whitestrips? A: According to Crest, you can use whitening strips up to twice every day.

Manufacturers like Crest encourage you to use whitening strips along with Crest whitening toothpaste for a brighter smile. However, whitening toothpaste marketing is very clever — and sometimes misleading.

At best, Crest’s whitening toothpaste may help remove some surface stains (called extrinsic staining). The peroxide in Crest Whitestrips, however, will actually whiten the tooth’s color.

Crest Whitestrips Before & After

Check out before & after results you may find with Crest Whitestrips:

Will Crest Whitestrips work for you?

To know if Crest’s popular strip treatments are the best choice for you, you should know if you’re dealing with enamel or dentin discoloration.

Enamel becomes discolored by staining, like when you drink a lot of red wine.

Dentin — usually considered the “inside” of your teeth” — is discolored by aging, poor nutrition, trauma, or smoking.

Crest Whitestrips use peroxide to whiten the deep dentin layer of your teeth. They may reduce the look of teeth stains, but that can just as easily be accomplished with a teeth whitening toothpaste.

Teeth that have greyed, rather than yellowed, are less likely to whiten significantly using peroxide-based whitening treatments like Crest Whitestrips.

You should not use Crest Whitestrips immediately before or after dental work, such as dental fillings or dentures.

Dental whitening kits will not whiten veneers, bonding, or anything besides your natural teeth.

The Best Alternatives to Crest Whitestrips

I don’t recommend most people use Crest Whitestrips more than once every 5 years or more.

For a whiter smile without exposing your mouth to potential dangers, consider these whitening alternatives:

Learn More:

There are some methods of teeth whitening I recommend avoiding entirely for safety reasons or because they’re ineffective. These include:

Zoom/light/halogen/LED/laser whitening

Whitening mouthwash

Chlorine bleach

Rubbing fruits on the teeth

How to Prevent Teeth Stains

For the whitest teeth possible, Crest Whitestrips aren’t your best option. Prevention is.

To prevent teeth from aging prematurely and yellowing:

Practice good oral care (brush, floss, tongue scrape, and oil pull regularly)

Drink water throughout the day

Limit staining foods and beverages like wine

Swish after staining foods and beverages

Schedule regular dental care and teeth cleanings

Mouth tape to reduce dry mouth

to reduce dry mouth Can’t mouth tape? Try a retainer

Treat teeth grinding (also known as bruxism)

Wear a mouthguard during sports

Key Takeaways

Crest Whitestrips are an inexpensive home teeth whitening method that can brighten your smile.

While they’re generally considered safe for occasional use, Crest’s teeth whitening kits contain some chemicals that may irritate the sensitive tissues in the mouth.

The safest way to use whitening strips is to cut them down to the height of your teeth. Do not let the strips touch your gums if at all possible.

UV lights used with Crest Whitestrips may increase tooth sensitivity and potentially damage tooth pulp.

It’s possible for white strips to leave discoloration on the teeth if the strips don’t adhere to the teeth evenly.

These products are not suitable for people with grey, rather than yellowing, teeth.