Topic Overview

Fluoride is a mineral that helps prevent tooth decay and dental cavities. It may be added to local water supplies, toothpastes, and other mouth care products. If your child is younger than 3 years, ask your dentist if it's okay to use a rice-sized amount of fluoride toothpaste. Use a pea-sized amount for children ages 3 to 6 years. Teach your child not to swallow the toothpaste.

Studies show a reduction in tooth decay in children if fluoride is added to or is found naturally in a community's water supply.footnote 1 To find out how much fluoride is in your drinking water, call your local water company or the local health unit. If you have your own well, have the local health unit check your water to find out if your family needs fluoride from other sources.

Normal amounts of fluoride added to public water supplies and bottled water are safe for children and adults. If your child needs extra fluoride, your dentist may recommend supplements. Use these supplements only as directed. And keep them out of reach of your child. Too much fluoride can be toxic and can stain a child's teeth.

If your child has a high risk of getting cavities, your dentist may recommend additional sources of fluoride. These include supplements or a gel or varnish the dentist applies to your child's teeth. Use supplements only as directed. And keep them out of reach of your child. Too much fluoride can be toxic and can stain a child's teeth.


Too much fluoride swallowed during the early childhood years may cause white, brown, or black spots or streaks on the outside of the teeth (fluorosis). This may also cause the tooth enamel to become rough.

  • Fluorosis develops during the first 8 years of childhood while the outer enamel layer of the teeth is still growing.
  • Fluorosis is not harmful to your general health. In rare, severe cases of stains caused by too much fluoride, a dentist may bleach the teeth to remove stains or may bond resin fillings onto the tooth to cover stains.

Can fluoride be dangerous?

Fluoride is safe in the amounts provided in water supplies but can be toxic in large amounts. Toxic levels depend on your child's weight. A lethal dose of fluoride for a 3-year-old child is 500 mg and is even less for a younger child or infant. Keep all products containing fluoride, such as toothpastes and mouthwashes, away from children. If you think your child may have swallowed too much fluoride, call your local poison control centre right away.

Related Information



  1. American Academy of Pediatric Dentistry (2013). Guidelines on fluoride therapy. American Academy of Pediatric Dentistry. Accessed December 3, 2013.


ByHealthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Brian D. O'Brien, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Specialist Medical Reviewer Arden Christen, DDS, MSD, MA, FACD - Dentistry

Current as ofNovember 20, 2015