Because over-the-counter teeth whitening strips may contain no more than 0.1% hydrogen peroxide, they generally only slightly reduce surface stains; they are not expected to noticeably lighten the natural colour of the tooth. Used according to the instructions they are not expected to cause serious harm, but sensitivity and gum irritation can occur. If you have decay, a leaking filling or a gum problem, it is advisable to have an examination before using strips.
What are teeth whitening strips and how do they work?
A teeth whitening strip is a thin, flexible plastic strip with one side coated in whitening gel. The strip is pressed onto the front surfaces of the teeth and left in the mouth for the time stated by the product.
The active ingredient in the gel is usually hydrogen peroxide or a compound that releases hydrogen peroxide. Some strips contain other stain-dissolving agents instead of peroxide. The strip holds the gel against the tooth surface, which reduces how much it is diluted by saliva to some extent.
Strips are mostly sold as separate pieces for the upper and lower arches. They only cover the front teeth; the gel does not reach the back teeth or the spaces between teeth.
Do teeth whitening strips work?
Teeth whitening strips often slightly reduce surface stains; they are not expected to noticeably lighten the tooth's own colour. The main reason for this is the legal limit placed on over-the-counter products.
Under Turkish and EU cosmetics rules, over-the-counter products may contain no more than 0.1% hydrogen peroxide. Products containing more than 0.1% and up to 6% hydrogen peroxide are supplied only through a dentist; the first application is carried out by the dentist and they are not used under the age of 18.
For this reason, the change people notice when using strips is usually a modest reduction in surface stains caused by tea, coffee and smoking. For details on active ingredients and concentrations, see the hydrogen peroxide and carbamide peroxide page.
Remember that some strips sold online, especially from abroad, may exceed these limits. It is safer to avoid products that do not clearly state their ingredients and concentration.
Are whitening strips harmful?
Strips within the legal limit generally do not cause serious harm when used according to the instructions. Even so, some side effects can occur, and the risk increases depending on how they are used.
- Sensitivity: Twinges with cold and heat are the most common side effect. In most cases they settle shortly after stopping use.
- Gum irritation: If the strip overlaps the gum, the gel can irritate it, causing redness or a burning sensation.
- Use without an examination: If there is unnoticed decay, an exposed root surface or a leaking filling, the gel can cause pain in these areas.
- Overuse: Extending the recommended time or repeating too often increases sensitivity; teeth may look grey or translucent.
- Unlabelled products: Products of unknown concentration carry a risk of marked sensitivity and gum burns.
The safety of strips and other whitening methods is covered separately on the is teeth whitening harmful page.
How are whitening strips used?
Always use whitening strips according to the product's own instructions; the duration and frequency vary by product. The steps below are a general framework.
- Have your teeth checked first: If you have decay, gum disease or sensitivity, have an examination before using strips.
- Dry your teeth: Gently dry the tooth surface with a clean tissue so the strip adheres better.
- Place the strip without overlapping the gum line: Press it on with the gel side against the teeth, and check the instructions before trimming any excess.
- Do not exceed the time: Leaving it on longer does not whiten more; it increases the risk of sensitivity and irritation.
- Remove the strip and rinse your mouth: Rinse off any gel left on the teeth and gums with water.
- Cut down on staining drinks during the treatment period: Tea, coffee and smoking have a negative effect on the result.
If you experience sensitivity or a burning feeling in the gums, take a break. If the problem does not settle within a few days, see a dentist.
Who should not use whitening strips?
Whitening strips are not suitable for everyone. In the following situations it is advisable to consult a dentist before use, or not to use them at all.
- People under 18
- Pregnant and breastfeeding women
- People with untreated decay or gum disease
- People with marked tooth sensitivity or gum recession
- People with large fillings, crowns or veneers on their front teeth (these do not whiten, so a colour mismatch can develop)
- People who know they are allergic to peroxide
For a detailed list, see the who should not have teeth whitening page.
The difference between whitening strips and clinical whitening
The main differences between strips and clinical methods are the concentration of gel used, the examination beforehand and supervision by a dentist. The table below compares the methods objectively.
| Feature | Whitening strips | Dentist-supervised at-home | In-office (light-activated) |
|---|---|---|---|
| Gel concentration | Up to 0.1% hydrogen peroxide | Above 0.1%, within legal limits | At the clinic, applied by the dentist |
| Examination beforehand | No | Yes | Yes |
| Gum protection | None | Limited contact with a custom tray | A protective barrier is applied |
| Teeth covered | Mostly the front teeth | All teeth covered by the tray | The teeth visible when smiling |
| Duration | Varies by product | Usually 1–3 weeks | A session takes about 45–90 minutes |
| Expected effect | Mild, mostly superficial | The tooth's own colour is lightened | The tooth's own colour is lightened |
For details of the methods, see the at-home teeth whitening and light-activated teeth whitening pages.
Strips or another method?
Which method suits you depends on the type of discolouration on your teeth. That is why it helps to find out the cause of the discolouration before deciding.
- Surface stains (tea, coffee, smoking): A professional scale and polish often makes a noticeable difference.
- The tooth's own yellow or grey shade: Dentist-supervised whitening with peroxide is needed.
- Fillings, crowns or veneers: These surfaces do not whiten; they may need replacing to match the colour.
- White spots: Whitening can make these spots more noticeable at first; the spot needs to be assessed first.
If there is tartar on the teeth, neither strips nor any other product can reach the surface underneath. So cleaning before whitening helps the result look more even and also reduces sensitivity.
For the effects of products other than strips (toothpaste, pens, LED kits), you can read the teeth whitening at home page.
Frequently asked questions
How many days do teeth whitening strips take to work?
It depends on the product and the type of stain on the teeth. With over-the-counter strips the change is usually mild and mostly comes from a reduction in surface stains.
Do whitening strips damage enamel?
Strips within the legal limit are not expected to seriously damage enamel when used according to the instructions. Acidic products, products of unknown concentration and overuse, however, can pose a risk.
What should I do if I get sensitivity while using whitening strips?
Take a break and use a fluoride toothpaste made for sensitive teeth. If the sensitivity does not settle within a few days, see your dentist.
Do whitening strips whiten fillings and crowns?
No. Fillings, crowns and veneers do not change colour with whitening products. If you have such restorations on your front teeth, a colour difference from your natural teeth may develop.
Can whitening strips be used with braces?
Brackets stop the strip from sitting properly on the tooth, and the area under the bracket does not whiten. Whitening is usually done after treatment ends, after waiting for a period recommended by the dentist.
Related pages
Teeth Whitening at Home: Do Over-the-Counter Products Work?Find out what strips, pens, toothpastes and LED kits really do, their risks, and how they differ from dentist-supervised take-home whitening.
Whitening Toothpaste, Pens, Powders and Gels: What Do They Do and Not Do?Learn the real effect of over-the-counter whitening products, the risk of abrasion and what to look for to choose wisely.Take-Home Teeth WhiteningControlled whitening done at home on your own schedule, with a custom tray and gel supplied by your dentist.
Who Should Not Have Teeth Whitening?Situations in which whitening is not recommended or should be postponed, and what needs to be done before treatment.
At-Home LED Teeth Whitening Devices: Does Blue Light Whiten Teeth?Find out what actually produces the effect in blue-light whitening devices used at home, why gel strength matters and what the possible risks are.Suitability is decided at an examination. Fill in the form or call us to book an appointment.
Last updated: 2026-11-04 · This page is for general information only and does not replace an examination or diagnosis.