Fluoride is a naturally occurring mineral used to strengthen teeth and prevent cavities. It’s been added to local water supplies in U.S. cities since the 1940s. There’s no evidence that fluoride is unsafe at appropriate levels.

Fluoride is a mineral in your bones and teeth, and it’s found in the air, water, soil, and plants.

You’re most likely to hear about it from dental and public health professionals, as it’s commonly used in dentistry to help prevent cavities and strengthen the outer layer of teeth known as the enamel.

Since the 1940s, fluoride has been added in small amounts to public water supplies throughout the United States and other countries through a process called water fluoridation.

Despite claims to the contrary, there is no evidence that the small amounts of fluoride used in water supplies are unsafe and a risk to public health.

For human health, fluoride is mainly used to improve dental health.

Fluoride has been added to local water supplies in U.S. cities since the mid-1940s.

According to the Centers for Disease Control and Prevention (CDC), 72.3% of the country’s population in 2022 received fluoride in their community water supply.

You may also find fluoride in many over-the-counter (OTC) products, including:

  • toothpaste
  • mouth rinses
  • supplements

If you tend to get many cavities, your dentist might suggest using a prescription mouth rinse with fluoride or a prescription strength toothpaste with fluoride. These products usually have a higher concentration of fluoride than OTC options.

Other products that might contain fluoride

Fluoride also has some non-dental uses. It’s used:

  • in medical imaging scans, such as PET scans
  • as a cleaning agent
  • in pesticides
  • to make Teflon, steel, and aluminum products

The American Dental Association describes fluoride in community water as the single most effective policy to prevent tooth decay. Research from 2023 shows that community water fluoridation has resulted in a more than 25% reduction in tooth decay for both children and adults.

Although the CDC doesn’t mandate fluoride in public water, it does note that water fluoridation ranks as one of the most important public health initiatives of the 20th century.

In general, fluoride is beneficial for teeth because it helps to:

  • rebuild (remineralize) weakened tooth enamel
  • slow down the loss of minerals from tooth enamel
  • reverse early signs of tooth decay
  • prevent the growth of harmful oral bacteria

How exactly does fluoride help your teeth?

When bacteria in your mouth break down sugar and carbs, they produce acids that eat away at the minerals in your tooth enamel. This loss of minerals is called demineralization. Weakened tooth enamel can make your teeth vulnerable to bacteria that cause cavities.

Fluoride helps remineralize your tooth enamel, reducing the risk of tooth decay and other dental health issues related to harmful bacteria in your mouth.

Global health authorities largely view the fluoride levels in drinking water today as safe, based on hundreds of studies worldwide examining the safety of adding low levels of fluoride to drinking water,

The Department of Health and Human Services recommends 0.7 milligrams of fluoride to each liter of water, which is about 3 drops of water in a 55-gallon barrel.

That’s been the recommended level since 2015. For the five decades before that, the upper range was 1.2 parts per milligram (ppm).

The World Health Organization has set a safe limit of 1.5 ppm for fluoride in drinking water.

Most of the research pointing to possible health risks focuses on fluoride levels twice as high as what’s been in most U.S. public water supplies for nearly a decade now.

Checking for fluoride in your water

Not every community in the United States fluoridates its drinking water.

If you’re unsure whether your community adds fluoride to your local water supply, you can use this CDC tool to check your local water supply in certain states. This tool can tell you whether your city fluoridates the water and, if so, how much fluoride is in the water.

If your city doesn’t fluoridate its water, but you’re interested in the dental health benefits of fluoride, try:

  • brushing your teeth twice a day with a fluoride toothpaste
  • using a fluoride mouthwash once a day
  • using no more than a smear or rice-size amount of fluoridated toothpaste for children ages 3 years old and younger; this may decrease the risk of dental fluorosis
  • using no more than a pea-sized amount of fluoridated toothpaste for kids ages 3 to 6 years old
  • asking your doctor about a professional fluoride treatment

If you’re concerned about your fluoride intake, you can reduce your exposure by:

  • finding alternative sources of drinking water, such as bottled water
  • using a fluoride filter for tap water
  • choosing fluoride-free toothpaste

Research from 2023 noted that findings indicating health risks are focused on excessive fluoride levels rather the smaller amounts in water supplies or other products like toothpaste. The research that focused on the recommended levels in public water supplies or dental products couldn’t be validated through other human studies.

In a 2022 position statement, the International Association for Dental, Oral, and Craniofacial Research (IADR) emphasized its support of community water fluoridation and pointed to it as “a safe and effective, evidence-based intervention” for preventing dental tissue destruction and decay.

Specifically, the IADR pointed to past research that didn’t show consistent or significant issues beyond the rare instances of dental fluorosis when exposed to higher levels of fluoride.

The most common reports of fluoride side effects include the following:

Dental fluorosis

This side effect can happen when you consume too much fluoride while your teeth are still forming under your gums. This results in white spots on the surface of your teeth.

Other than the appearance of white spots, dental fluorosis doesn’t cause any symptoms or harm.

Skeletal fluorosis

Early symptoms of skeletal fluorosis include joint pain and stiffness. Over time, it can alter bone structure and cause ligament calcification. It tends to result from long-term exposure to higher levels of fluoride, often in drinking water. Several factors can cause excessive fluoride in water, including accidental contamination from fires or explosions.

Other health claims

However, some anecdotal reports and older research claim that fluoridated water causes a variety of health problems, including:

Research from 2021 cast doubt on some of the claims above, including fluoridated water’s effect on cognitive ability.

Despite claims and older, questionable research looking at possible fluoride risks from fluoride, the scientific community consensus is that the lower levels of fluoride in public water supplies or dental products people most commonly use don’t have a negative effect.

Fluoride is a naturally occurring mineral used in many dental products to strengthen tooth enamel and prevent cavities. It’s also added to the local water supplies in many U.S. cities.

While the amount added to drinking water is considered relatively safe, exposure to high fluoride levels may be linked to several health issues.

If you’re concerned about your fluoride intake, ask your local government about the fluoride in your city’s water. You can also opt for fluoride-free dental products, especially if you have young children, who may be at a higher risk of dental fluorosis.