Children can also ingest too much fluoride more slowly over time. Children younger than age eight who consume fluoride in their drinking water and also in supplements -- or who swallow fluoridated toothpaste or mouth rinses instead of spitting them out -- can develop a condition called dental fluorosis, in which excess fluoride gets into teeth that are developing, before they have erupted through the gum line. The excess fluoride causes the tooth enamel to develop white or brown stains and sometimes appear pitted.
To prevent fluorosis, the American Academy of Pediatric Dentistry, the Centers for Disease Control and other organizations suggest discussing whether your child needs fluoride supplementation carefully with the dentist, and telling the dentist whether or not your tap water is fluoridated. Do not give your child fluoride toothpaste until he is at least two years old, and then watch him carefully (until he is about age six) to make sure he doesn't swallow it. Do not give your children fluoride rinses until they are at least six years old, or as recommended by their dentist.