Oral Health›Everyday care

Fluoride Explained

What fluoride does for your teeth, how strong your toothpaste should be in the UK, Australia and the US, and what health bodies say about fluoride in water, varnish and safety.

Updated September 2026·By the OHA editorial team·10 min read·How we write
Key takeaways
  • Fluoride strengthens tooth enamel and helps repair early damage from decay.
  • Adults in the UK should use toothpaste with at least 1,350 ppm fluoride. Advice for young children differs by country, so follow local guidance.
  • Use a smear or pea-sized amount for children, supervise brushing, and spit rather than rinse.
  • Public health bodies in the UK, Australia and the US support water fluoridation; in the US it is under federal review.
  • Too much fluoride while children's teeth are forming can cause fluorosis, which is usually mild.

Fluoride is a natural mineral found in water, soil, tea and some foods, and it is added to most toothpaste. The Oral Health Foundation says tooth decay has reduced worldwide largely because people use fluoride toothpaste. Where countries' advice differs, this guide gives each one separately.

What does fluoride do?

The American Dental Association explains that bacteria in plaque feed on sugars and release acids that attack enamel, the hard outer layer of the tooth. Fluoride helps repair this early damage, a process called remineralisation, and makes enamel more resistant to future acid attacks.

The Australian Dental Association adds that fluoride stops mouth bacteria using sugar to make acid, and that it works best when low levels are present in your mouth throughout the day.

How strong should your toothpaste be?

Toothpaste strength is measured in parts per million (ppm) of fluoride, printed on the tube or box. For children, the right strength and amount depend on where you live.

United Kingdom (NHS)

  • Adults: at least 1,350 ppm.
  • Children under 3: a smear of toothpaste with no less than 1,000 ppm, brushed by a parent or carer, starting when the first tooth appears.
  • Children aged 3 to 6: a pea-sized amount with 1,000–1,500 ppm.
  • Children 7 and over: 1,350–1,500 ppm.

The NHS also says children do not need special children's toothpaste: family toothpaste with 1,350–1,500 ppm is suitable at any age.

Australia (Australian Dental Association, healthdirect)

  • Birth to 17 months: no toothpaste. Brush with water only, unless a dentist advises toothpaste because your baby is at high risk of decay (healthdirect).
  • 18 months to 6 years: a children's low-fluoride toothpaste, which the Australian Dental Association says contains 500 ppm. The advice on amount varies slightly: the Australian Dental Association says a smear, while healthdirect says a small pea-sized amount.
  • Over 6 and adults: standard toothpaste, which the Australian Dental Association says ranges from 1,000 to 1,450 ppm.

The Better Health Channel (Victoria) says that if your drinking water is not fluoridated, a dental professional may advise starting toothpaste earlier or moving to standard toothpaste sooner.

United States (American Dental Association)

  • Children under 3: fluoride toothpaste from the first tooth, no more than a smear or an amount the size of a grain of rice.
  • Children aged 3 to 6: no more than a pea-sized amount.
  • Older children and adults: fluoride toothpaste twice a day. The American Dental Association says toothpastes sold in the US generally contain 1,000–1,500 ppm.

The CDC gives the same amounts but adds a caution for the youngest children: for children under 2, check first with your doctor or dentist about using fluoride toothpaste.

The biggest difference is for babies and toddlers. The UK and the American Dental Association advise fluoride toothpaste from the first tooth, the CDC advises checking with a doctor or dentist first for under-2s, and Australia advises none until 18 months and then a lower-strength paste. If you are unsure, ask your dentist.

Higher-strength toothpaste

If you are at high risk of decay, a dentist may prescribe a stronger toothpaste. The Oral Health Foundation lists 2,800 ppm (age 10 and over) and 5,000 ppm (age 16 and over) in the UK, for people with frequent decay, dry mouth or gum recession, among others. The American Dental Association says prescription toothpaste in the US contains 5,000 ppm.

Spit, don't rinse

The NHS advises spitting out excess toothpaste after brushing without rinsing, because rinsing washes away the concentrated fluoride left on your teeth.

Fluoride in drinking water

Community water fluoridation means adjusting the fluoride in a public water supply to a level that helps prevent decay. Levels are given in milligrams per litre (mg/L), which is the same as ppm.

United Kingdom

About one in ten people in England receive water from a fluoridation scheme, which aims for 1.0 mg/L (Department of Health and Social Care). The government's 2026 health monitoring report for England concluded that water fluoridation is a beneficial public health measure for reducing tooth decay in children, with the largest benefits in more deprived areas and no convincing evidence of harm to non-dental health.

Australia

The National Health and Medical Research Council (NHMRC), Australia's national health research body, strongly recommends water fluoridation as a safe, effective and ethical way to reduce tooth decay. It supports levels between 0.6 and 1.1 mg/L and says around 89% of Australians had access to fluoridated water in 2017.

United States

The CDC recommends 0.7 mg/L and, in its 2024 scientific statement, said fluoridation reduces tooth decay by about 25% in children and adults. The American Dental Association continues to support it.

The US position is now contested. The Environmental Protection Agency (EPA) is carrying out an accelerated review of fluoride in drinking water that looks only at possible harms, including to brain and tooth development. It published the review's assessment plan in January 2026 and later its method. Announcing the review, the US Health Secretary said a growing body of evidence indicates that swallowing fluoride can cause neurological harm. The American Dental Association disagrees, and has criticised the review for leaving out recent studies that found no link between optimally fluoridated water and children's cognitive abilities. The review had not concluded at the time of writing. Our guide to water fluoridation has a fuller, dated timeline for each country.

Not all reviews agree on the size of the benefit

A 2024 Cochrane review found that in studies since 1975, adding fluoride to water may lead to slightly less decay in children's baby teeth, but it could not be sure about adult teeth. It concluded that the benefits may be smaller than before fluoride toothpaste became widespread. The American Dental Association, by contrast, says fluoridation still prevents at least 25% of decay even with widespread fluoride toothpaste use. They reach different conclusions about how large the benefit is today.

Filters and bottled water

The American Dental Association says reverse osmosis and distillation systems can remove fluoride, while carbon filters do not, and the Better Health Channel says boiling does not significantly change fluoride levels. The NHMRC and the American Dental Association both note that many bottled waters contain little fluoride.

Fluoride varnish

Fluoride varnish is a high-strength fluoride coating painted onto the teeth by a dental professional. The NHS says children aged 3 and over should be offered it at least twice a year, and younger children may be offered it if their dentist thinks they need it. It can be used on both baby and adult teeth.

A Cochrane review of 22 trials found that children treated with fluoride varnish had on average 43% fewer decayed, missing or filled surfaces on adult teeth and 37% fewer on baby teeth, based on moderate-quality evidence.

What is dental fluorosis?

Dental fluorosis is a change in the appearance of tooth enamel caused by taking in too much fluoride while the teeth are forming. The Better Health Channel describes it as fine, pearly-white flecks or lines that are usually very hard to see, and says it cannot develop once the teeth have fully formed. The CDC says this window lasts until about age 8.

Estimates of how common it is vary. An earlier version of the Cochrane review estimated that at 0.7 mg/L, about 40% of people may have some fluorosis and about 12% may have fluorosis that bothers them. The NHMRC says moderate fluorosis is very uncommon and severe fluorosis rare in Australia. The CDC says most cases in the US are mild and do not affect how teeth work.

To lower the risk, use only a smear or pea-sized amount of toothpaste for children and encourage them to spit it out (Oral Health Foundation). The American Dental Association says children under 6 should not use mouthwash unless a dentist recommends it, because they are more likely to swallow it.

Is fluoride safe?

The Oral Health Foundation says fluoride is safe and very effective when used in the right amount. On water fluoridation, the NHMRC found reliable evidence that fluoridation at Australian levels is not associated with cancer, Down syndrome, lowered intelligence or hip fracture, and the 2026 report for England found no association with children's cognitive ability. In the US, the EPA review described above is re-examining possible harms.

When to see a dentist
  • You notice white, brown or discoloured marks on your child's teeth.
  • You are unsure which toothpaste strength suits your child, especially if your water is not fluoridated.
  • You or your child have frequent decay, a dry mouth or braces, and want to ask about higher-strength fluoride.
  • Your child is 3 or older and has not been offered fluoride varnish.

Frequently asked questions

Is fluoridated water in my area?

Your local water supplier can tell you, according to both the Oral Health Foundation and the Better Health Channel.

Is low-fluoride children's toothpaste strong enough?

In Australia, the Australian Dental Association recommends a 500 ppm children's toothpaste from 18 months to 6 years. In the UK, the NHS recommends at least 1,000 ppm for young children. A dentist may advise a stronger toothpaste if your child is at high risk of decay.

Can I be allergic to fluoride?

The Australian Dental Association says no, citing the American Academy of Allergy, Asthma and Immunology, which reports that fluoride ions are too small to be an allergen.

Sources

  1. Fluoride, Oral Health Foundation (the NHS fluoride page now redirects here), accessed September 2026
  2. How to keep your teeth clean, NHS, accessed September 2026
  3. Children's teeth, NHS, accessed September 2026
  4. Water fluoridation: health monitoring report for England 2026, UK Health Security Agency and Department of Health and Social Care, accessed September 2026
  5. Tips for choosing toothpaste, Australian Dental Association, accessed September 2026
  6. Fluoride, Australian Dental Association, accessed September 2026
  7. Looking after your baby or child's teeth, healthdirect Australia, accessed September 2026
  8. Dental care: fluoride, Better Health Channel, accessed September 2026
  9. 2017 Public Statement: Water fluoridation and human health in Australia, National Health and Medical Research Council, accessed September 2026
  10. Fluoride, American Dental Association (MouthHealthy), accessed September 2026
  11. Fluoride: topical and systemic supplements, American Dental Association, accessed September 2026
  12. Fluoride in water, American Dental Association, accessed September 2026
  13. EPA initiates accelerated review of fluoride in drinking water, ADA News, 6 February 2026, accessed September 2026
  14. Fluoride in drinking water, US Environmental Protection Agency, accessed September 2026
  15. EPA announces next step in gold standard review of fluoride to inform protective recommendations, US Environmental Protection Agency, 22 January 2026, accessed September 2026
  16. CDC scientific statement on community water fluoridation, CDC, accessed September 2026
  17. Community water fluoridation frequently asked questions, CDC, accessed September 2026
  18. Does adding fluoride to water supplies prevent tooth decay?, Cochrane, accessed September 2026
  19. Fluoride varnishes for preventing dental caries in children and adolescents, Cochrane, accessed September 2026
  20. About dental fluorosis, US Centers for Disease Control and Prevention, accessed September 2026
  21. Consultation on community water fluoridation expansion in the north east of England: government response, Department of Health and Social Care, March 2025, accessed September 2026

This article is general information about oral health. It is not a diagnosis or a substitute for advice from a dentist or doctor who knows your situation. If you have pain, swelling, bleeding that does not settle, or a problem that is getting worse, see a dental professional. In an emergency, contact your local emergency service.

How to Brush Your Teeth Properly
Twice a day, two minutes, fluoride toothpaste, a soft brush and a gentle technique. Here is what that looks like in practice, and the small habits that make it work better.
Choosing a Toothbrush
Head size, bristle firmness, manual or electric, and brushes for children, braces and people who find brushing hard. What health bodies say to look for, and how to look after your brush.
Toothpaste Explained
What is in toothpaste and why, how strong the fluoride should be, what sensitivity and whitening toothpastes can and cannot do, when a stronger prescription paste helps, and the ingredients people ask about.