At the Dentist

Crest Whitestrips: Do They Work? And Are They Safe?

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Before you use Crest Whitestrips, you should know that they’re not as safe as you might think. Some of these ingredients are dangerous to the teeth and gums—and there’s a better alternative.

by Dr. Burhenne

Crest Whitestrips
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Crest Whitestrips seem like the perfect solution to a smile that’s less white than you’d like—they’re convenient, affordable, and more popular than ever. But the question is: Do Crest whitestrips really work?

In truth, teeth whitening strips do work to make teeth look whiter and brighter. But there are a number of reasons why I don’t think they should be your first choice for teeth whitening.

Namely, they can cause damage to the teeth and gums, while also increasing sensitivity and pain.

But before I explain how Crest whitening strips (by P&G Brands) and similar brands work and can cause harm, I want to explain why teeth get stained and yellowed in the first place.

Later, I’ll also share some safer and more effective ways to brighten your smile and provide advice on how to prevent discoloration. That way, you won’t need to comb the shelves of your local drug store in search of a quick teeth whitening fix.

Let’s get started!

How do teeth get stained?

There are two parts of your teeth—the inner dentin and outer enamel. Here’s a look at how the dentin and enamel can become stained or discolored.

Causes of Dentin Discoloration

Age: As we age, our dentin naturally becomes more yellow. Even with the whitest possible enamel, yellow dentin will cause teeth to look yellow because its color is refracted through the outer enamel like a prism.

Grinding and dental trauma: Any trauma to the tooth—whether caused by grinding (also known as bruxism), a fall, or direct force—causes the tooth to age prematurely. And, as mentioned above, aging dentin is yellow dentin.

Poor nutrition or hydration: Missing out on important nutrients? Your teeth will eventually show it as lack of proper nutrition also causes dentin to age sooner than it should. This can also happen when you don’t drink enough water, as your mouth (and entire body) needs to stay hydrated to stay young.

Other causes: There are other rare reasons your dentin can become yellow, like:

  • Taking the antibiotic tetracycline before 10 years old
  • A genetic disorder called amelogenesis imperfecta
  • Amalgam/mercury fillings
  • Genetics (some people are just more likely to have yellower teeth)

Causes of Enamel Staining

Highly pigmented foods and beverages: Certain foods and drinks like wine, kombucha, and coffee can cause staining of the teeth’s outer enamel. Rinsing your mouth with water during and after can help minimize staining.

Dental fluorosis: Drinking fluoridated water as a child often causes dental fluorosis, which can cause white or brown discolorations on teeth. While most major organizations say this impact of fluoride only happens to children, many adults find their permanent teeth are also discolored from fluoride.

Unfortunately, fluorosis can’t be reversed (and it’s a sign of more serious problems).

Tobacco: Similarly to pigmented beverages, the tobacco in cigarettes, chew, and cigars will yellow the enamel of your teeth.

How Crest Whitestrips Work + How to Use Them

Crest Whitestrips and similar products work by coating the teeth with a gel that contains hydrogen peroxide or carbamide peroxide. This gel is pressed against the teeth long enough for its ingredients to penetrate the teeth and create a whitening effect.

Whitening strips are small pieces of a flexible plastic called polyethylene, a common plastic that is safe for one-time use. Once coated with a whitening gel, each strip is molded around the teeth—one strip for the top and one strip for the bottom.

While the plastic used by whitestrips is seemingly non-toxic, the adhesive chemicals may be problematic for some.

Crest Whitestrips use polyvinylpyrrolidone (PVP) to bind strips to teeth. The Environmental Working Group (EWG) rates this adhesive as safe, meaning it doesn’t bioaccumulate or disrupt hormones, like many household chemicals. (1) The strips also contain carbomer, another fairly safe chemical, to increase adhesion of the gel. (2)

Though they are considered safe, these adhesives can irritate the gums and unnecessarily damage enamel, especially when overused.

And regarding hydrogen peroxide, the whitening agent used in these strips, there is no question about its potential danger.

It is true that hydrogen peroxide does whiten teeth. This chemical can pass into the enamel of the tooth and help reverse some discoloration of both teeth and dentin by breaking down the organic molecules inside that make teeth look yellow.

But the European Union (EU) and Canada’s governmental body classify hydrogen peroxide as toxic or harmful when used in the mouth, and I totally agree with that assessment. (3)

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

I’m also concerned about the pH-balancing ingredient in whitestrips, sodium hydroxide. It’s an ingredient considered toxic when used inside the body and is a “caustic agent,” meaning it corrodes what it touches. (4)

How to Use Crest Whitestrips

When you open a package of whitening strips, you’ll see that there are different packets for upper and lower sets of teeth. Remove each strip from the packet and cut away any additional area that would touch your gums. Then, adhere the strips to the appropriate teeth.

Most Crest Whitestrips are designed to be worn about five minutes each day—even the Crest website suggests not using them for longer without risking increased tooth sensitivity!

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

According to Crest, you can use whitening strips up to twice every day. You should not brush your teeth before using whitening strips. Many people choose to brush afterwards, but this risks pressing down the abrasive chemicals into the enamel of your teeth.

Never wear Crest Whitestrips overnight or while sleeping/napping.

Manufacturers like Crest encourage you to use whitening strips along with Crest whitening toothpaste for a brighter smile. But these options are worse for you in the long run.

Problems with Crest Whitestrips

Here are some of the major problems I see with Crest Whitestrips and similar at-home whitening methods:

Gum Damage

The chemical reaction that must occur in order to make your teeth appear whiter can damage your gums. But it’s not just the whitening process that’s dangerous—both sodium hydroxide and PVP can irritate gums, particularly the former. This is why it’s essential to make sure that whitening strips never touch your gums.

This is hard to do, but it’s possible: If you do use white strips, cut the strips so they don’t overlap with or touch your gums, as they should touch only your teeth.

Yellow Spots

Whitening strips are one-dimensional, but teeth are three-dimensional. This creates a problem when it comes to getting the results you want because the flat strips can’t get into the in-between spaces or the curved bottoms of teeth. Often, the center of the tooth is whitened, but the curved edges of the tooth remain yellow or gray.

The spots that weren’t whitened don’t become more yellow than before—they simply look more pronounced because the color difference is so striking. And it’s likely that your unevenly whitened teeth may be even more of a cosmetic frustration than having evenly discolored teeth.

Tooth Damage

When a dentist isn’t around to monitor a whitening treatment, I get a little nervous. It is very possible to overdo it and damage your teeth.

This is especially true with at-home whitening, because these agents work by breaking down and altering enamel.

The truth is, enamel is there to protect your teeth from decay, so overuse of Crest Whitestrips and other products may cause unnecessary damage and make you more susceptible to cavities.

Increased Sensitivity or Pain

Damaging the enamel of your teeth can inadvertently expose more of the dentin, which is the living, inner layer of tooth tissue.

After using Crest Whitestrips or other at-home whitening kits, you may notice your teeth become more sensitive to hot or cold, or that you experience soreness or pain throughout your mouth when eating certain foods, especially sugary treats.

At the very least, you should visit your dentist and make sure you don’t have any cavities before using whitening strips.

Problems with the Oral Microbiome

Hydrogen peroxide kills bacteria very successfully—which is exactly why you don’t want in your mouth.

You need a balance of good bacteria in your mouth in order to prevent cavities and other oral health issues, but hydrogen peroxide totally disrupts the balance of your oral microbiome and may cause more issues than the cosmetic one you’re trying to fix. (It’s the same reason I recommend avoiding toothpastes that contain essential oils.)

The Best Alternatives to Crest Whitestrips

As you may have guessed, I’m not the biggest fan of Crest Whitestrips. However, there are a number of alternative options that can help you achieve a whiter smile.

In my opinion, the best whitening strips are no whitening strips at all.

There are two types of whitening—extrinsic (removing stains) and intrinsic (actually whitening enamel)—and each are achieved via different methods.

Best Extrinsic Whitening Methods

There are some great natural teeth whitening methods that can remove years of stains and external damage caused by pigmented drinks.

Before I share my favorites, though, I want to say this as an aside: Many people recommend teeth whitening at home via apple cider vinegar or strawberries. These things work because the acids they contain corrode the top layer of enamel.

Sure, you’ll see some stains go away at first, but using acidic agents like this can make your teeth age faster, which will make your dentin yellow more quickly and cause more discoloration in the long run.

In fact, I tell my patients to rinse their mouths with water after eating foods that contain vinegar, citrus, or acidic fruits such as strawberries.

  1. Turmeric

My DIY Turmeric Teeth Whitening Paste uses the power of turmeric, one of the most powerful herbs on the planet, to remove stains.

Turmeric has primarily been researched because of its anti-inflammatory and disease-fighting prowess. (5, 6) But there has been some anecdotal support for its ability to remove dental stains.

To make this paste, you’ll combine turmeric with baking soda, L-arginine, and coconut oil. Not only will it help with removing stains, but it will also promote proper balance of your oral environment and help to prevent gum disease and other inflammatory concerns.

  1. Activated Charcoal

Activated charcoal is another powerful, stain-removing ingredient. Known as a detoxifier, activated charcoal binds to toxins and chemicals and serves as a vehicle to remove them from the body. In a similar fashion, it can bind to molecules on the teeth that cause discoloration from eating pigmented foods and drinks.

This DIY Activated Charcoal Toothpaste Recipe will allow you to replace your Crest Whitestrips with a much safer alternative. You simply let it sit for 5-10 minutes on the teeth to bind to stains before rinsing.

I want to point out that I don’t recommend brushing your teeth with most store-bought charcoal toothpastes, as the particles they contain can be too abrasive for enamel. Instead, you can buy activated charcoal powder to use in a paste like the one I developed, but just smear the paste on and let it sit, rather than brushing it on.

  1. Stain-Removing Toothpaste

For stain removal, I believe the best whitening toothpaste is Rembrandt Intense Stain. But even though I recommend this brand, you shouldn’t use it regularly.

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Rembrandt Intense Stain

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2-3 weeks is all you should need to get rid of some of the more obvious stains—anything longer than that may start to erode the enamel.

Many people flock to whitening toothpastes to try to achieve a whiter smile. As I’ve mentioned, you can remove some extrinsic stains this way, but you won’t be able to actually change the color of your enamel or dentin with toothpaste.

  1. An Electric Toothbrush

One of the best ways to eliminate stains and brighten teeth is to use a good electric toothbrush. For this purpose, the Oral-B electric models are my favorite, and any model from the 1000 to the 7000 will work well. (Feel free to check out my review of the Oral-B 7000.)

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Oral-B Pro 1000

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Oral-B Pro 7000

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The 3D White Brush Head or the Cross Action Brush Head designed for these Oral-B models do a great job at removing and disorganizing the biofilm that causes teeth to become stained (just remember, you’ll have to purchase the heads separately from the brush).

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Oral-B 3D White Brush Head

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Oral-B Cross-Action Brush Head

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I also recommend the new Goby electric toothbrush. It is modeled after the Oral-B design and is great for removing stains from teeth. Even better, the Goby is much more affordable because you purchase it directly from the manufacturer and don’t have to pay any retail markups.

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Goby Toothbrush (Black)

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Goby Toothbrush (Gold)

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The Goby can be purchased on a subscription model, which means that you never have to remember to buy replacement brush heads again—they’ll be delivered right to your door every 1-3 months.

The Best Intrinsic Whitening Method

Custom Whitening Trays

If you really want to whiten the enamel of your teeth and aren’t satisfied with the result of just removing external stains, I recommend just one choice: professional teeth whitening at your dentist’s office.

During this process, your dentist will take impressions of your teeth and create a custom tray that you can use indefinitely.

The biggest benefit of these—especially when compared to a product like Crest Whitestrips—is that the trays prevent the gel from touching and damaging the gums and other soft tissues in your mouth.

Additionally, custom trays have a better fit. As a result, all surfaces of your teeth will get coated with the whitening gel, leading to a more even result.

In comparison to whitening strips—which run around $40 per box and often, are used every few months, and must be regularly replaced—a custom tray costs around $250-300 and lasts forever, unless your teeth move.

Also, the peroxide gel you use in the trays is very inexpensive (usually less than $30 per syringe) and can be easily purchased on Amazon as needed. My favorite whitening gel is Opalescense by ULTRADENT.

Pro tip: Your dentist may recommend you buy whitening gel from his/her office, but it’ll often cost you three to four times more than simply buying it online.

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Opalescense Teeth Whitening Gel

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The only major con to whitening with a custom tray is that the strong chemical used in them can cause sensitivity to hot and cold for about 24 hours after use.

To minimize any consequences as much as possible, be sure to always follow your dentist’s instructions, and don’t use it too often.

A Final Note on Intrinsic Whitening

There are some methods of teeth whitening I recommend avoiding entirely for safety reasons. These include:

  • Zoom/light/halogen/LED/laser whitening: These methods are ineffective and can destroy the nerves of your teeth.
  • Whitening mouthwash: Because whitening ingredients need to be held against the teeth for a sustained period of time in order to be effective, whitening mouthwash doesn’t work either. It also exposes your sensitive gums to bleach.
  • DIY whitening: Many DIY whitening recipes contain acidic ingredients like strawberry or lemon. These ingredients can wear away the enamel on teeth and contribute to decay and other dental issues.

Stain Prevention: The Best Way to Keep Teeth White

If you really want to have the whitest small possible, Crest Whitestrips aren’t your best option.

Prevention is.

Here are a few options for preventing teeth from aging and yellowing too fast, while also catching stains before they stick:

  • Stay hydrated: Drinking adequate amounts of water during the day both rinses your mouth of stain-causing compounds from foods and drinks and prevents dry mouth, which can lead to decay and premature yellowing.
  • Limit staining foods and beverages: A glass of wine is good for the body (and soul), but try to limit the amount of time each day you eat or drink items that will stain your teeth.
  • Swish after staining foods and beverages: If you do consume any highly pigmented foods or drinks, you should rinse your mouth with water immediately after. Brushing is a good idea, too—just be sure to wait 30-45 minutes, as enamel may be more vulnerable to erosion just after eating or drinking.
  • Get regular cleanings: Allowing your dental hygienist to remove tartar and calculus from your teeth every 6-18 months is a great prevention to tooth decay that may lead to premature yellowing.
  • Stop mouth breathing: A dry mouth is a major cause of tooth decay and aging teeth. Mouth breathing is a major cause of dry mouth, but practicing nasal breathing during the day and using mouth tape at night can help reverse this dangerous habit.
  • Treat teeth grinding (also known as bruxism): If you grind your teeth, it’s important to get to the root cause of the issue. You may find that you’re grinding your teeth because of sleep apnea, a condition that is caused by a blocked airway during sleep. Grinding is your body’s way of opening up the airway, but it causes significant damage to the teeth, including early aging/yellowing.
  • Wear a mouthguard during sports: To limit the damage to your teeth caused by sports injury, always wear a mouthguard while playing contact sports.

Final Thoughts on Whitening Strips

You may be considering using Crest Whitestrips or a similar at-home teeth whitening method. While there’s nothing wrong with wanting a brighter smile, whitening strips contain adhesives and whitening agents that are dangerous to the mouth, especially the gums.

When overused, the whitening chemicals can damage your enamel, cause increased tooth pain or sensitivity, and wreck your oral microbiome. Worse, they don’t whiten evenly and can leave yellow spots on teeth.

If you want your teeth to appear whiter, you must first decide which method of whitening you really need:

Are you looking to extrinsically whiten your teeth, simply removing the stains from long-term wine or coffee drinking, for example? Or do you want to intrinsically whiten teeth, actually changing the color of your enamel?

To remove stains extrinsically, I recommend a few methods:

If you want to intrinsically whiten your teeth, the safest and most effective option is a custom whitening tray molded by your dentist. You can then fill the tray with a whitening gel like Opalescense by ULTRADENT that can be purchased online.

Although Crest Whitestrips do technically work to create a brighter smile, I just don’t think they’re worth the risk. There are much safer, and more effective, options available.

Are you thinking of another whitening method I haven’t mentioned? Just ask me about it here.

read next: What Is the Best Whitening Toothpaste?


  1. Environmental Working Group (EWG). (2018). PVP. Retrieved from:
  2. Environmental Working Group (EWG). (2018). Carbomer. Retrieved from:
  3. Environmental Working Group (EWG). (2018). Hydrogen peroxide. Retrieved from:
  4. Environmental Working Group (EWG). (2018). Sodium hydroxide. Retrieved from:
  5. Mali, A. M., Behal, R., & Gilda, S. S. (2012). Comparative evaluation of 0.1% turmeric mouthwash with 0.2% chlorhexidine gluconate in prevention of plaque and gingivitis: A clinical and microbiological study. Journal of Indian Society of Periodontology, 16(3), 386. Full text:
  6. Nagpal, M., & Sood, S. (2013). Role of curcumin in systemic and oral health: An overview. Journal of natural science, biology, and medicine, 4(1), 3. Full text:

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