Teeth whitening

Expert reviewer Dr Steve Preddy, Dentist
Next review due October 2020

Teeth whitening uses bleaching methods to lighten the colour of your natural teeth. You may want to whiten your teeth if they’ve lost their whiteness overtime, or because of smoking or stains from food and drink.

You may see the results after just a few days, but it can take several weeks.

An image of a lady smiling

About teeth whitening

Teeth whitening offers the advantage of lightening the colour of your teeth without removing any of the surface of your tooth.

Bleaching is the most common way to whiten your teeth. Products usually contain either hydrogen peroxide or carbamide peroxide. When these chemicals break down, they release oxygen. This gets into the hard, outer surface of your teeth (the enamel) and whitens them. How long the whitening effect lasts is different for everyone but it can be up to three years. For more information, see our FAQ: How long will teeth whitening last? below.

In general, you need to be 18 years old to have teeth whitening, although this depends on your individual circumstances.

Only dental professionals registered with the General Dental Council can whiten your teeth. These include professional dentists and dental hygienists, therapists and technicians. For more information, see our FAQ: Who can do teeth whitening? below.

Talk through your teeth whitening treatment with your dentist. Your treatment might be different from what we describe here, as it’ll be designed to suit you.

Preparing for teeth whitening

It’s important for your dentist to assess your teeth fully before you have your teeth whitened. This is to make sure that you don’t have any problems, such as tooth decay or inflamed gums.

Your dentist will show you on a chart what shade of white your teeth will be by the end of the treatment. And they’ll give you an idea of how long it will take.

Your dentist will take impressions of your upper and lower teeth and use them to make plastic trays that fit your mouth. They’ll use these during your treatment to apply the bleaching product to your teeth.

Teeth whitening methods

The best and safest way to whiten your teeth is to visit a qualified dentist. They’ll use either external or internal bleaching methods.

External bleaching

If you have external bleaching, your dentist will make sure they protect your gums with a shield or gel. They’ll then use custom-made mouth trays (like a mouthguard), to apply a whitening product to your teeth.

Your dentist will give you the bleaching product, and instructions on how to use it, so you can continue whitening your teeth at home. How often you need to do this, and for how long will depend on the bleaching product. It can vary from 30 minutes to an hour at a time. For some products, you’ll need to leave them on for eight hours. Depending on which product you use, you might start to see results after one to four weeks.

Power bleaching

Your dentist may offer you a type of external bleaching called power bleaching. In this procedure, they apply the bleaching product onto your teeth, and then shine a very bright light onto them. The light is thought to speed up the whitening process by reacting with the bleaching product. But there’s little scientific proof that it’s better than other types of bleaching.

Internal bleaching

Internal bleaching can help lighten the colour of teeth that have darkened from having root canal treatment.

First, your dentist will re-open the hole that was made for your root treatment. They’ll then put the bleaching product into it. Your dentist will seal the hole with a temporary filling, leaving the bleaching product inside your tooth.

You’ll need to go back to your dentist after about a week to have the temporary filling and bleaching product changed. At each visit, your dentist will also check if the treatment is working. You might need to go back a couple of times before the treatment is complete. At this point, your dentist will close the hole permanently with a tooth-coloured filling.

Teeth whitening home kits

You can buy teeth whitening products over the counter in most pharmacies in the UK, as well as online. They include home tray kits and whitening strips. But these products don’t always work – only a dentist can safely and legally get your teeth the whitest.

If you're thinking about using a home method of teeth whitening, it’s a good idea to speak with your dentist first – they may be able to recommend which one to use. Make sure you read the instructions and follow them carefully.

Taking care of your teeth after treatment

It’s important that you have realistic expectations of how much your teeth can be whitened with bleaching methods. Talk to your dentist about this before you begin the treatment. How long the whitening effect lasts also varies from person to person but you might not need to re-whiten your teeth for up to three years. This will depend on how well you look after your teeth after treatment.

It’s important to continue to brush and floss your teeth properly after your treatment. If you smoke, stop and try to limit the amount of food and drink that you consume, which can stain your teeth to a minimum.

You can watch our animations to see how to brush and floss your teeth properly. And for more tips and advice about how to look after your teeth, see our topic: Caring for your teeth.

How to brush your teeth

How to floss your teeth

Side-effects of teeth whitening

If you have treatment with a qualified dental professional, registered with the General Dental Council, teeth whitening is generally safe. But as with every procedure, there are some risks to consider. Your dentist will discuss these risks with you, before the treatment.

If you’re pregnant or breastfeeding, it’s best to delay having your teeth whitened until after you give birth. This is because doctors don’t know if the whitening products can affect your baby.

Side-effects are the unwanted, but mostly temporary, effects you may get after a treatment. After having your teeth whitened, you may have:

  • more sensitive teeth, especially to the cold
  • a sore throat
  • tender gums
  • white patches on your gums

These side-effects should go away after a few days. Contact your dentist if they don’t.

Alternatives to teeth whitening

The bleaching products used for teeth whitening only work on natural teeth, so cannot lighten the colour of false tooth materials like dentures, crowns or bridges. Depending on your situation, you may have to consider the following alternatives.

  • Veneers. These are thin layers of porcelain or other material that your dentist can attach to the front of your teeth. While they can improve tooth colour, they usually involve altering your teeth. For example, your dentist may need to remove some of the enamel that naturally protects your teeth to make way for the veneer.
  • Crowns. A crown is like a ‘cap’ that’s placed over a natural tooth, after your dentist has shaped it to make room for the crown. It’s usually made of a ceramic material or porcelain and can improve the colour of individual teeth if, for example, you have fillings that have become dark.

For more information on veneers and crowns, see our topic: Restoring teeth.

There are other things you can do to help improve the appearance of your teeth. These include:

  • brushing your teeth with a fluoride toothpaste at least twice a day, and always before going to bed
  • flossing your teeth regularly
  • stopping smoking and cutting down on food and drink that can stain your teeth, such as blueberries, tea, coffee and red wine
  • using a whitening toothpaste – these can’t make your teeth whiter, but can help remove some of the stains
  • visiting your dentist regularly – they can scale and polish your teeth to remove any tartar that has built up

Frequently asked questions

  • To have your teeth whitened well and safely, it’s important to see a qualified dentist or dental professional. Only dental professionals registered with the General Dental Council can do teeth whitening. These include professional dentists and dental hygienists, therapists and technicians. It’s illegal for anyone else, such as a beautician or hairdresser to offer the procedure. This is the case even if they’ve attended a teeth whitening training course, or say they have valid insurance. The General Dental Council ( has more advice about this.

  • The price of teeth whitening can vary and often depends on where you live, as prices vary across different regions.

    Your dentist should give you an estimate of how much teeth whitening will cost before you start your treatment. Power whitening uses a very bright light to enhance the whitening, which is thought to produce the desired results more quickly. Although there’s little scientific proof this works any better than other bleaching techniques. But this may be more expensive than the standard method.

  • The whitening effects can last for up to three years. This varies from person to person, and may depend on how well you look after your teeth and on the type of treatment you have.

    Things like eating, drinking, smoking and tooth-brushing can all affect how long the whitening treatment lasts. If you smoke or have lots of food and drinks that can stain your teeth, such as red wine or coffee, the effects won’t last as long. If you smoke, try to quit – as well as being better for your health, it will help to keep your teeth as white as possible.

    Different methods of teeth whitening can lead to different results too. Talk through all the options with your dentist before you make a decision. They’ll give you advice you on how long the effects are likely to last for each type of treatment.

  • Lots of things can cause your teeth to lose their natural whiteness overtime. These include:

    • natural changes in the colour of your dentine (the inner part of your teeth) as you get older
    • eating food and drinks with strong colourings, such as blueberries, tea, coffee and wine
    • smoking, which can make your teeth look yellow
    • tartar (plaque that can build up and harden on your teeth, usually if you don’t brush your teeth properly)
    • tooth fillings used for root canal treatments
    • taking medicines, such as antibiotics and iron supplements
    • having tiny cracks in the enamel of your teeth that take up stains

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Related information

    • Tooth whitening. Oral Health Foundation., accessed 4 October 2017
    • Teeth whitening. British Academy of Cosmetic Dentistry., accessed 5 October 2017
    • Personal communication, Dr Steve Preddy, Bupa Dentist, 10 October 2017
    • Tooth discoloration. Medscape., updated 7 September 2015
    • Restorative dentistry. Oxford handbook of clinical dentistry (online). Oxford Medicine Online., published August 2010
    • Position statement on tooth whitening. General Dental Council., published 11 July 2016
    • Statement on the safety and effectiveness of tooth whitening products. American Dental Association., published April 2012
    • Crowns. Oral Health Foundation., accessed 2 October 2017
    • Teeth whitening: top tips for your patients. British Dental Association., accessed 5 October 2017
    • Tooth whitening. General Dental Council., accessed 5 October 2017

  • Reviewed by, Rachael Mayfield-Blake, Freelance Health Editor, October 2017
    Expert reviewer Dr Steve Preddy, Dentist
    Next review due October 2020

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