Fluoride is a naturally occurring mineral found in water in varying amounts, depending on which area you live in.

Information written and reviewed by Certified Doctors.




Over the past 50 years, much research has been carried out into the health benefits of fluoride. Fluoride’s main benefit is that it strengthens tooth enamel (the hard outer surface of the tooth), which provides protection against tooth decay.

When the level of fluoride found naturally in water is low, fluoride is added to the supply of drinking water. This process is known as fluoridation.

One study compared the levels of tooth decay in children as young as three years of age in areas where the water supply was fluoridated and areas where it was not fluoridated. The study found that children living in the fluoridated areas had nearly 60% less tooth decay than those living in non-fluoridated areas.

Fluoride can also be manufactured. This type of fluoride is called ‘synthetic fluoride’ and it is often added to toothpaste.

You can read more about the dental benefits of fluoride.

Tooth decay

Tooth decay, also known as dental decay or dental caries, is a major health concern worldwide, with children at particular risk.

Tooth decay occurs when acid in your mouth attacks the outer layers of your teeth. The acid is produced by bacteria that form a layer called plaque on the surface of your teeth.

Eating and drinking sugary food and drink is the main cause of acid formation in plaque.

If you have poor dental hygiene and you leave plaque on your teeth, a cavity (hole) may develop in your tooth. The tooth can then become infected, which can be painful. A dental abscess (a collection of pus that forms in the teeth or gums) may also develop.

Read more about tooth decay.

How does fluoride protect teeth?

Fluoride disrupts the process of tooth decay by:

  • changing the structure of developing enamel, making it more resistant to acid attack - these structural changes occur if a child consumes fluoride during the period when enamel develops (mainly up to seven years of age)
  • encouraging better quality enamel to form that is more resistant to acid attack
  • reducing plaque bacteria’s ability to produce acid, which is the cause of tooth decay


Around half a million people in the UK receive naturally fluoridated water. Another 5.5 million people receive water that has had the fluoride concentration raised to around one part per million (1ppm). This level of fluoridation has been shown to have the most benefit for developing strong teeth and protecting against tooth decay. The maximum amount of fluoride permitted in drinking water is 1.5 mg/l (milligrammes per litre).

It is recommended that water should be fluoridated in areas where the amount of fluoride found in natural water is low. However, it is up to individual local health authorities in consultation with health groups and the local community to decide whether or not to add fluoride to their water supplies.

Your local water supplier should be able to tell you whether fluoride is being added to your water supply.

Fluoride treatments

Dentists recommend that children and adults should brush their teeth using toothpaste that contains fluoride. For those who are particularly prone to tooth decay, mouthwash, gels and tablets containing higher concentrations of fluoride are also available. Ask your dentist for advice before using these treatments.

Fluoride varnish is another treatment that can be used to help protect against tooth decay. The varnish contains high levels of fluoride and is painted onto the surface of both baby and adult teeth, usually every six months. It works by strengthening the tooth enamel, making it more resistant to decay.

Safety and risks

There have been some concerns that fluoride may be linked to a variety of health conditions, including bone problems such as bone cancer.

Extensive research has found no evidence to support these concerns and scientists agree that water containing the correct amount of fluoride and fluoride toothpaste have a significant benefit to oral health, help reduce tooth decay and do not cause any harmful side effects to a person's overall health.

However, a condition called dental fluorosis can occur if a child’s teeth are exposed to too much fluoride when they are developing. This can occur if fluoride supplements are taken by children under seven years of age who live in areas where the water supply is fluoridated.

Mild dental fluorosis can be seen as very fine pearly white lines or flecking on the surface of the teeth. It can often only be identified by a dental expert. Severe fluorosis can cause the tooth’s enamel to become pitted or discoloured.

Content supplied by NHS Choices