FluorideMineral

• Tooth decay — topical fluorideLikely helps

  A large body of Cochrane systematic reviews finds topical fluoride — toothpaste, mouthrinse, gel and varnish — consistently lowers caries rates [8].
  
  There is a dose-response by toothpaste concentration, which is unusual for this catalog and strengthens the finding [8].
  
  Adding a second topical fluoride product on top of fluoride toothpaste buys a further 10% caries reduction (95% CI 2–17%) — real, but modest [8]. ^[8]

• Tooth decay — community water fluoridationLikely helps

  A 2015 Cochrane review of 20 mostly pre-1975 studies found children on fluoridated water had 35% fewer decayed, missing or filled primary teeth and 26% fewer permanent ones [1].
  
  A 2018 NHANES analysis agreed: living where at least 75% of water reached 0.7 mg/L meant 30% less primary-tooth decay and 12% less permanent-tooth decay [1].
  
  Adults show a benefit too. Australians with 14 or more years of exposure had 11–12% lower decayed, missing or filled tooth rates than those with negligible exposure [1]. ^[1]

• Tooth decay — fluoride tablets and drops for childrenPossibly helps

  A 2011 Cochrane review of 11 trials in 7,196 children found 0.25–1 mg/day for 24 to 55 months cut decayed, missing or filled tooth surfaces by 24% in permanent teeth [1].
  
  The same review could not say what supplements did for primary (baby) teeth — the two trials covering that disagreed [1].
  
  A 2013 systematic review reported far bigger reductions, 48–72%, but rested on non-randomized trials, a weaker evidence base [1].
  
  Use of these supplements has been falling in high-income countries in favour of topical fluoride, given fluorosis risk and methodological weakness in the older trials [1]. ^[1]

• Fluoride supplements taken during pregnancyPossibly helps

  A 2017 Cochrane review found no good evidence that maternal fluoride supplementation lowers caries in the child's baby teeth [1].
  
  Only one low-quality 1997 randomized trial met its inclusion criteria, so this is close to an empty evidence base rather than a negative finding [1].
  
  Topical fluoride — toothpaste and professionally applied varnish — is considered safe throughout pregnancy, per a 2025 dental caries review [7]. ^[1]

• Bone density and fracture riskPossibly helps

  Fluoride does stimulate new bone formation, but it is not an established osteoporosis therapy — and one trial found it made things worse [1].
  
  A 2008 meta-analysis of 25 RCTs (954 participants) found lower vertebral and nonvertebral fracture risk at daily doses up to 20 mg, and not above that [1].
  
  A later RCT in 180 postmenopausal women found no bone-density change either way at 2.5–10 mg/day over one year [1].
  
  One trial at a pharmacologic 60 mg/day of sodium fluoride went the other direction: more vertebral fractures and peripheral bone loss [1]. ^[1]

• More tooth decay than in comparable populations with adequate exposure — this is how the MSD Manual frames low fluoride intake for consumers [9]
• Weaker enamel where exposure was inadequate while the teeth were still forming [1]
• There is no blood or serum marker of fluoride status, per NIH ODS, so no personal deficiency can actually be diagnosed [1]
• In practice, 'fluoride-deficient water' means water below about 0.7 mg/L, not a diagnosable condition in a person [1]
• Flagged: some commercial dental pages list gum disease, bad breath, delayed tooth eruption and dry mouth as deficiency signs. No government or academic source reviewed here corroborates that list^[1]

• Sodium fluoride (NaF)Everyday use. It is also one of three additives, with fluorosilicic acid and sodium fluorosilicate, used to fluoridate…

  Elemental content

  The most widely used fluoride salt — most toothpaste at 1,000–1,500 ppm, prescription paste at 5,000 ppm, varnish at 22,600 ppm (2.26%) [6]

  Absorption

  Mouthrinses come at 0.05% NaF (230 ppm) for daily home use, or 0.2% (920 ppm) weekly or by prescription [6].
  
  It is also the salt in most dietary fluoride tablets and drops, at 0.25, 0.5 or 1 mg per dose [1]

  Best for

  Everyday use. It is also one of three additives, with fluorosilicic acid and sodium fluorosilicate, used to fluoridate US municipal water [6].

• Stannous fluoride (SnF2)Plaque and gingivitis alongside decay.

  Elemental content

  The other main toothpaste active. Its tin(II) component adds antibacterial and antigingivitis activity that sodium fluoride does not have [6]

  Absorption

  Head-to-head studies split on how much better it is. Several found it beat NaF or monofluorophosphate on enamel loss and plaque; others found no significant difference [6].
  
  The antibacterial effect of the stannous ion is on firmer ground than any extra anti-caries edge over NaF

  Best for

  Plaque and gingivitis alongside decay. The trade-offs: it is chemically less stable, needs stabilizers, and can cause mild extrinsic tooth staining [6].

• Sodium monofluorophosphate (MFP)An alternative toothpaste active.

  Elemental content

  A third toothpaste active-ingredient option alongside NaF and stannous fluoride [6]

  Absorption

  Used the same way as the other two toothpaste actives — brushed on, spat out, not swallowed

  Best for

  An alternative toothpaste active. It comes up far less often than NaF or stannous fluoride in the comparative studies reviewed here [6].

• Acidulated phosphate fluoride (APF)Professional and prescription settings only.

  Elemental content

  A concentrated 1.23% (12,300 ppm) gel or rinse, deliberately acidic at around pH 3 [6]

  Absorption

  The acidity was found in early research to raise how much fluoride the enamel takes up [6].
  
  Applied in-office for 1 to 4 minutes, or used as a once-daily prescription home rinse

  Best for

  Professional and prescription settings only. Its concentration is exactly why it is used far less often than daily self-applied products [6].

• Silver diamine fluoride (SDF)Root caries in older adults, and children or patients with limited access to dental care.

  Elemental content

  A colourless liquid, roughly a quarter silver and 5–6% fluoride by weight [6]

  Absorption

  Painted straight onto the lesion rather than brushed on or swallowed [6].
  
  FDA-cleared as a Class II device for tooth sensitivity, and used off-label to arrest active caries lesions

  Best for

  Root caries in older adults, and children or patients with limited access to dental care. The catch: it stains the application site permanently black [6].

• Difluorsilane varnishAn alternative where 2.26% sodium fluoride varnish is not the choice .

  Elemental content

  A much weaker varnish at 0.1% (1,000 ppm fluoride) [6]

  Absorption

  Painted onto the tooth surface like sodium fluoride varnish, at roughly a twentieth of the concentration

  Best for

  An alternative where 2.26% sodium fluoride varnish is not the choice [6].

• Dental fluorosis

  This is the common consequence of too much fluoride, and it can only happen while teeth are still forming under the gums — up to about age 8 [6].
  
  Per NHANES 1999–2004, 20.8% of Americans aged 6–49 had mild or very mild dental fluorosis, 2.0% moderate and under 1% severe [1].
  
  Most of it is cosmetic — white flecks or lines — does not affect oral-health quality of life, and tends to fade in severity through adolescence [1].
  
  Flagged: older NHANES analyses suggested fluorosis was rising over a decade, but a later CDC data-quality review called that increase 'not biologically plausible' and traced it to a change in how examiners scored it [1]. ^[1]

• Acute overdose and skeletal fluorosis

  NIH ODS puts the acute dose capable of serious systemic toxicity at about 5 mg/kg body weight — roughly 375 mg for a 75 kg adult [1].
  
  Symptoms of a large acute ingestion include nausea, vomiting, abdominal pain, diarrhea, periostitis and, rarely, death [1].
  
  That dose is essentially unreachable from normally fluoridated water or toothpaste [1].
  
  Chronic excess is linked to skeletal fluorosis — joint pain and stiffness through to osteoporosis, muscle wasting and neurological effects [1].
  
  It is extremely rare in the US, and not tied to standard water fluoridation levels. ^[1]

• The fluoride and child-IQ question

  This is genuinely contested, and the two headline findings are about different concentrations.
  
  A 2023 meta-analysis of 8 studies found no association between fluoride at typical US community water levels and lower child IQ [1].
  
  A 2024 National Toxicology Program review concluded with moderate confidence that water above 1.5 mg/L — more than double the 0.7 mg/L US target — is associated with lower child IQ [1].
  
  That NTP review explicitly did not address concentrations at or near the recommended US level. The two are frequently cited as if they contradict each other; on dose, they do not [1]. ^[1]

• Voriconazole

  NIH ODS reports that fluoride has no known clinically relevant medication interactions, with exactly one exception [1].
  
  The oral antifungal voriconazole contains fluoride in its own molecular structure, and roughly 4 or more months of use can push serum fluoride high enough to cause skeletal fluorosis or periostitis [1].
  
  The drug's prescribing information advises stopping it if either develops [1]. ^[1]

• Calcium, magnesium and aluminum

  This one is nutrient-nutrient rather than drug-drug. Dietary calcium, magnesium and aluminum form poorly absorbed complexes with fluoride and cut how much gets absorbed [1].
  
  MedlinePlus and Cleveland Clinic both instruct avoiding dairy for 1 hour before and after a fluoride supplement, and keeping calcium, magnesium or aluminum antacids 2 hours away [10][12].
  
  The 1997 Institute of Medicine DRI report confirms the mechanism: solid food and calcium-rich liquids like milk or infant formula measurably slow and reduce fluoride absorption [2]. ^[12]

Fluoride is a trace presence in most foods. Anything not prepared with fluoridated water typically supplies under 0.05 mg per 100 g, per NIH ODS's summary of USDA data [1].

Brewed tea is the standout, because tea plants accumulate fluoride from soil — reported at 0.3–6.5 mg/L, or roughly 0.07–1.5 mg per cup, depending on tea type and the water used [1].

After tea come coffee, canned shrimp (0.17 mg per 3 oz), raisins, oatmeal, grapefruit juice, baked potato and cooked rice, each in the range of 0.02–0.22 mg per serving [1].

Most other everyday foods — meat, eggs, fruit, plain dairy, bread — give 0.01 mg or less per serving when made without fluoridated water [1].

Tap water dominates. Fluoridated municipal water, drunk directly and used in cooking, accounts for about 60% of total US fluoride intake, and 62.9% of the US population had access to it as of 2020 [1].

Breast milk is very low and barely responds to the mother's own water fluoride, often below detection or 0.002–0.01 mg/L when measurable. Cow's milk is similar at 0.007–0.086 mg/L [1].

Infant formula runs under 0.2 mg/L for milk-based and 0.2–0.3 mg/L for soy-based — before counting whatever the tap water used to mix it adds, which matters for fluorosis risk [1].

Bottled water is generally not fluoridated. Most brands sit under 0.3 ppm unless sold as fluoride-added 'nursery water' or drawn from naturally fluoride-rich sources; deliberate addition is capped at 0.7 mg/L total [1].

For dietary supplements (tablets, chewables, infant drops), MedlinePlus and Cleveland Clinic agree the dose is taken once daily [10][12].

Keep dairy 1 hour either side of the dose, since dietary calcium binds fluoride and cuts absorption [10][12].

Cleveland Clinic specifically suggests taking the tablet after brushing at night, and keeping calcium, magnesium or aluminum antacids at least 2 hours away [10].

To get the topical benefit as well as the systemic one, the ADA says tablets and lozenges should be chewed or sucked for 1–2 minutes before swallowing, not swallowed whole [6].

Infant drops are measured with a dropper and can be given straight or mixed into cereal, juice or food; tablets can be dissolved into water, juice or formula [12].

For toothpaste, which is topical rather than systemic, the ADA recommends brushing twice daily, on waking and before bed [6].

Brushing spikes salivary fluoride 100- to 1,000-fold, returning to baseline within 1–2 hours — so the topical benefit is short-lived after each brushing [6].