I began this list of teeth whitening strips with teeth whitening products that could potentially make it into this roundup, looking at factors like brand reputation, buyer reviews on Amazon and full reviews by other writers. After narrowing the lengthy list of teeth whitening strips, I started testing.

It would be impossible to test the long-term efficacy of all of these whitening strips without annihilating my enamel and gum tissue or distinguishing results with back-to-back testing on my own teeth, so I judged each product against a few criteria that I think will help you make a buying decision.

Before buying your next box of teeth whitening strips, consider these factors.

Fit

You want your strips to fully cover your teeth and not go up over your gums, which can cause gum sensitivity. Additionally, their fit should be snug. While you go about your day waiting for it to be time to take the strips off, they should not slip and slide inside your mouth.

Coverage

While whitening your molars is not necessary (since you hardly see them anyway), your teeth whitening strips should still cover a good percentage of your teeth. After you apply the strip, smile and look in the mirror. Is the strip touching all of the teeth you can see in your normal smile? If not, time to try another brand.

Ease of use

Whitening strips should be simple. Apply the product, wait a specified amount of time and take the strips off. If the teeth whitening strips require other steps or seem difficult to use, try another brand.

Sensations

If you have sensitive teeth or gums, look for products that will give you the least amount of sensitivity. Oftentimes, hydrogen peroxide is too strong for sensitive teeth, so try coconut oil, instead. Don’t suffer through a product if it burns your gums or hurts your teeth.

Length of wear

Most strips require at least 30 minutes of wear in order to get the best results. If you have sensitive teeth or not enough time for teeth whitening strips, look for products that don’t require much wear.

“Over-the-counter teeth whitening strips contain low to moderate concentration of hydrogen peroxide or carbamide peroxide gel. The peroxide penetrates the tooth enamel to break down stain molecules,” explains Sandip Sachar, DDS, who has been practicing general and cosmetic dentistry in Midtown Manhattan, NYC, for over 20 years. “Whitening strips often include advanced adhesives that keep the strip and peroxide in close contact with the teeth. They can gently lighten the tooth color after repeated applications. Typically, it takes 5-14 daily applications to achieve satisfactory results.”

After about a week of daily use, according to Man, most people start seeing their teeth get noticeably whiter.

“Generally, yes, but they’re not right for everyone,” answers Man. “The FDA regulates these products, and many have the American Dental Association’s seal of approval. However, people with certain dental conditions like cavities, gum disease or very sensitive teeth should check with their dentist first. Even healthy teeth can become sensitive during whitening.”

Man states that problems tend to occur when people are unaware of underlying dental issues or don’t follow the product directions. “If you experience persistent pain or sensitivity, stop using them and see your dentist,” she advises.

According to Sachar, DIY products can be riskier. “These include products that contain chlorine dioxide or sodium chlorite, which can thin enamel and increase the risk of tooth decay,” she says. “These are not ADA-approved ‘natural’ or ‘fast-acting’ whitening products, and I do not recommend them as they are not safe.”

“It’s like comparing a professional car wash to doing it yourself in the driveway,” states Man. “Professional whitening uses stronger bleaching agents and gives you dramatic results in just one or two visits. Plus, if something goes wrong, your dentist is right there to fix it. They can also customize the treatment for your specific needs and address any sensitivity issues immediately. Strips are the DIY option that costs way less and lets you whiten while binge-watching Netflix. The downside? It takes longer to see results, and you might end up with some uneven spots if your teeth aren’t perfectly straight.”

Sachar provides the following advantages and disadvantages for each type of treatment:

Advantages of at-home whitening strips:

• More affordable than professional in-office treatments.
• Convenient and easier to use on your own schedule.
• Gradual whitening allows for subtle changes over time instead of quick one-day whitening.
• Reduced risk of sensitivity.

Disadvantages of at-home whitening strips:

• Lower peroxide concentrations mean slower and less dramatic results.
• Strips may not fit perfectly, which can lead to uneven whitening, especially between the teeth or along the gumline.
• Greater chances of improper use resulting in adverse side effects, such as leaving them on too long.

Advantages of professional teeth whitening:

• Fast and dramatic results in just one or two visits.
• Custom trays that fit the teeth exactly are sometimes included for continued home whitening or touch-ups.
• Protection for the gums to prevent sensitivity.
• Supervised by a professional, reducing the risk of misuse or complications.
• Professional in-office peroxide concentrations with enhanced activation using LED or laser light can produce a more dramatic and fast result.

Disadvantages of professional teeth whitening:

• Significantly higher cost.
• May cause temporary tooth sensitivity in some patients.
• Less convenient, requiring scheduling and attending a dental visit.

“For patients that have more sensitive teeth, I advise them to use whitening strips with a lower peroxide concentration, or that contain desensitizing agents like potassium nitrate or fluoride,” advises Sachar. “I recommend patients with sensitive teeth start using toothpaste for sensitive teeth, fluoride toothpaste or fluoride rinse, 1-2 weeks prior to whitening. I advise them also to space out the treatments with longer times between treatments. I advise them to avoid strips with harsh flavorings or containing unnecessary acids that can irritate the teeth and gums. Look for ‘gentle’ formulas like ‘Crest 3D White Gentle Routine.'”

According to Man, you should take a break and call your dentist if “your teeth start feeling like they’re getting electric shocks.”

Start with a dental checkup: “I always recommend starting with a dental checkup before any whitening routine,” recommends Man. “Your dentist can spot potential issues and help you choose the safest, most effective approach for your specific situation.“

Follow directions closely: “Regardless of the product used, technique matters,” says Sachar. “I advise patients to brush gently before applying the strips to make sure the teeth are plaque-free and avoid food and drinks that stain teeth for 24-48 hours after whitening. I recommend always following the instructions closely, including never exceeding the recommended frequency or duration.”

Wait to brush after whitening: “After whitening, always wait at least 30 minutes before brushing to allow enamel to re-harden and reduce the risk of abrasion or sensitivity,” advises Sachar. “Brushing too soon can damage the temporarily softened enamel and irritate gums.”

Note that some discoloration may require in-office treatment: “While whitening strips can be effective for many people, professional whitening often provides more predictable and longer-lasting results,” Man states. “Strips work great for everyday stains from food and drinks, but some types of discoloration from medications or other causes may need professional treatment.”