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Are teeth whitening strips bad for you?

Updated: Nov 6, 2023

A noticeable negative side effect of teeth whitening strips is teeth sensitivity. However the whitening strips are relatively safe because the sensitivity tends to dissipate a few days after discontinuing use.

This article will explore the risks and benefits of using whitening strips on your teeth. They are easily accessible at your local pharmacies but are they worth it and are they even effective?

Over the counter whitening strips

What are teeth whitening strips?

Whitening strips are an over the counter teeth whitening product where you brighten your teeth at home on your own time. The strips are made of a flexible piece of plastic that is coated in a whitening gel that is either composed of:

  • Hydrogen peroxide

  • Carbamide peroxide

Fortunately, these gels are made of the same materials used in professional dental office products albeit at a lower concentration.

Since the teeth whitening strips use the same ingredients as professional products by your dentist, that makes them effective for whitening teeth. However, they will always be less effective than a professional product since it uses a lower concentration of the ingredients. They may work very well for some individuals while not very much for others but it depends on each person's teeth situation.

Nonetheless, without further ado, here is how to use them.

How to use teeth whitening strips

There are various brands that offer a similar product but the most well known and commonly available is the Crest 3D Whitestrips:

  1. Peel. Remove the strips from the packaging.

  2. Apply. Place the strips over your upper and bottom teeth.

  3. Boost. Use the Crest LED accelerator light for 5 minutes to speed up and enhance the whitening effects.

  4. Remove. Keep the strips on for 30 minutes and then remove.

  5. Smile.

Here is a video on how to do it by Crest:

The LED light accelerator is suppose to mimic the popular ZOOM whitening product. You can give it a try but just for disclosure, our dental office prefers the KoR whitening system, which does not use a light.

Are whitening strips bad for your teeth?

When teeth whitening strips are used properly and in moderation, they are not bad for your teeth but they do have undesired consequences when overused. The most prominent side effect is that they make your teeth sensitive afterwards. Although sensitivity isn't exclusive to whitening strips because that is a common side effect for whitening in general.

Here is how the sensitivity after whitening may affect your daily life:

  • Sensitivity while drinking cold beverages.

  • Sensitive to cold air.

What we mean by overuse is if you decide to use a strip every hour on the hour even though the instructions say just once a day. Misuse in such a manner may result in some serious teeth sensitivity as well as possible damage to your teeth. There is also a good chance that you'll end up in excruciating pain.

However, as long as you follow the instructions and use in moderation it is safe to use. For most people who are reasonable, the side effect of teeth sensitivity is mostly self-limiting. The reason is because most people will stop using the product once they reach a certain threshold of sensitivity.

What happens is that as they use it more and more, the sensitivity will increase more and more until they reach a point where they simply discontinue it. It is sort of a self defense mechanism where your body tells you to stop.

So, yes they can be bad but it is unlikely for you to cause any severe damage to your teeth due to the reasons above. We could also make the same argument about taking Tylenol for headaches. If you take an entire bottle of Tylenol that will be the last headache you'll ever have. However if you follow the instructions properly and take it in moderation it can help you relieve your headache. Whitening strips will whiten your teeth but if you use too much you will end up in pain. Same reasoning.

Everything in moderation please but overall, we would have to rate the typical crest whitening strips as fairly safe. It is definitely less sensitive than ALL of the professional whitening products by your dentist!

Pros and Cons of teeth whitening strips

No product is absolutely perfect and that includes whitening strips, which come with their own set of benefits and detriments.


  • Effective in whitening teeth. Since it contains the same whitening ingredient as professional products, for some people this product is more than enough to whiten their teeth to the desired color.

  • Cost effective. Readily accessible and easily affordable because they cost a fraction of a professional teeth whitening product.

  • Least sensitive option. Due to the strips having a lower concentration than a product by your dentist, they will also be the least sensitive and most tolerable. Consequently this also makes it a safer product to use while breastfeeding.


  • Uneven whitening. The whitening strips are not custom made to follow the contours of your teeth, which causes uneven whitening. It can miss corners, crooks and crannies of certain teeth.

  • Accidentally whiten gums. Since the strips don't follow the scalloping of the gum margins, sometimes the whitening gel can bleach the gums white. This is transitory and will return back to their pink color after discontinuing use.

  • Not strong enough. For some individuals who have tougher teeth staining, the low concentration of the strips may not be enough. If that is the case, they should seek out a stronger product by a dentist, which comes in a higher concentration.

Custom made whitening trays by your dentist can address all three of the cons from whitening strips. The shape of the custom trays will conform and hug every contour of your teeth. This ensures that the gel can reach every nook and cranny of your teeth to produce a more even brightening effect.

Here is a picture of custom trays for the procedure:

kor take home trays

It is pretty obvious in the photo above that the professional take home kits are superior just because it conforms to your teeth. Another reason is that it helps in preventing saliva from washing away the whitening gel. As you may know, there are a lot of enzymes that will break down and dissolve the whitening material. The trays offer a better seal to protect the gel compared to the strips, which don't hug your teeth as closely.

The Verdict

We recommend for all of our patients to start off with teeth whitening strips if they've never whitened before because it may be effective and also to test your tolerance for teeth sensitivity.


For some people, this product may work brilliantly and they need not spend money on a product by their dentist, which inherently costs more. That makes it a very accessible and easily affordable option if it works. The worst that can happen is that it doesn't work but in that case you can just make an appointment with your dentist to give the next step a try.

Sensitivity tolerance

If you've never whitened your teeth before, you wouldn't know if you can tolerate the sensitivity that comes from a higher concentration product by your dentist. Since the strips are at a lower concentration, it is good to see if you can handle that first. If you cannot tolerate sensitivity from the whitening strips, you'll never be able to do the in office treatments.

There is an exponential increase in sensitivity when you go from whitening strips to take home products from your dentist. Then once again there is another large increase if you do an in office session.

Therefore, in our opinion the strips are amazing in that they let you "test the waters" to see if you are even eligible to do an in office whitening session. If you can't handle it, then the in office session would've been a waste of money and time.


David Chen 200 x 200.jpg

About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

Association Memberships:

Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!

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