Fluoride supplements

What it is

Fluoride is the ionic form of the element fluorine. NIH ODS states it inhibits or reverses the initiation and progression of dental caries and stimulates new bone formation. Dietary fluoride supplements are a small category of products, usually sodium fluoride, given as lozenges, tablets or liquid drops. Cochrane records that they were first introduced to provide systemic fluoride where water fluoridation is not available.

What the research says

The state of the evidence: the Cochrane review of fluoride supplements found a benefit in the permanent teeth of school-age children compared with no supplement, but rated the trials as providing weak evidence, found no advantage over topical fluoride such as toothpaste, and could reach no conclusion for children under six. Most of the trials predate near-universal fluoride toothpaste, and the reviewers say the effect in children already brushing with fluoride toothpaste would probably be limited. On the harm side, excess fluoride during tooth formation causes dental fluorosis, acute overdose causes gastrointestinal illness and rarely death, and a 2025 meta-analysis found an inverse association between fluoride exposure and children's IQ.

Evidence grade: Limited evidence.

What goes wrong

Cochrane found insufficient evidence to say whether fluoride supplements in children under six cause dental fluorosis, and limited information on adverse effects generally. (Source 1)

• Systematic review, Very low certainty.
• Size: 11 studies, 7,196 children.
• Who: children, in particular those under 6 years of age.
• How long: minimum follow-up of 2 years.
• Result: no pooled estimate; the review recorded fluorosis only where studies reported it and found the data insufficient.
• Funding: not stated.

Moreover, insufficient evidence exists to show whether or not using fluoride supplements in young children (less than 6 years of age) could mottle teeth (fluorosis), an effect of chronic ingestion of excessive amounts of fluoride.

A 2025 systematic review and meta-analysis found an inverse association between fluoride exposure and children's IQ, including a dose-response association with urinary fluoride. (Source 2)

• Meta-analysis, Low certainty.
• Size: 74 studies (64 cross-sectional, 10 cohort); 20,932 children in the main group-level analysis.
• Who: children in 10 countries, most studies from China; 52 of 74 studies rated high risk of bias.
• How long: prenatal and postnatal exposure windows.
• Result: pooled SMD −0.45 (95% CI −0.57 to −0.33, P < .001); 1.63 IQ points lower (95% CI −2.33 to −0.93) per 1 mg/L increase in urinary fluoride, and 1.14 points among low risk-of-bias studies; the drinking-water association was null below 1.5 mg/L.
• Funding: not stated in the abstract; the work arose from the US National Toxicology Program review programme.

Analysis of 13 studies with individual-level measures found an IQ score decrease of 1.63 points (95% CI, −2.33 to −0.93; P < .001) per 1-mg/L increase in urinary fluoride.

NIH ODS lists fluoride supplements inappropriately given to children among the causes of acute fluoride toxicity, which can include death in rare cases. (Source 3)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: general, with children singled out.
• How long: acute.
• Result: nausea, vomiting, abdominal pain, diarrhoea, periostitis and rarely death; the acute dose estimated to cause serious systemic toxicity is 5 mg/kg (about 375 mg for a 75 kg adult)
• Funding: government body.

High doses of fluoride (typically from rare accidents resulting in excessively high levels of fluoridation of water, unintentional ingestion of fluoride products intended for topical use in dentists' offices, or fluoride supplements inappropriately given to children) can result in nausea, vomiting, abdominal pain, diarrhea, periostitis, and even death in rare cases.

Of 150 reported ingestions of sodium fluoride caries-prevention preparations, 36 children had symptoms, most commonly vomiting, and none had effects worse than local gastrointestinal ones. (Source 4)

• Case series, Very low certainty.
• Size: 150 poison-centre cases, 36 symptomatic.
• Who: mostly children aged one to three years (85% of ingestions)
• How long: acute; most symptoms began within the first hour.
• Result: vomiting 28 cases (77.8% of symptomatic), nausea 5 (13.9%), diarrhoea 3 (8.3%); 67% of symptomatic cases resolved in under an hour; liquid preparations averaged 46.9 mg or 5.2 mg/kg and caused symptoms more often.
• Funding: not stated.

Limit of this finding: The percentage in this quote does not match the paper's own denominator. It reports 36 symptomatic children out of 150 cases and calls that 26 percent, but 36 of 150 is 24 percent. The quote keeps the figure as the paper printed it. Rely on the counts - 36 of 150 - rather than the percentage. Nothing else in the finding depends on it: the point is that roughly a quarter of these children had symptoms and none had anything worse than local gastrointestinal effects.

Thirty-six (26 percent) children exhibited symptoms which included nausea (5 cases, 13.9 percent), vomiting (28 cases, 77.8 percent), and diarrhea (3 cases, 8.3 percent). There were no symptoms more serious than these local effects.

NIH ODS reports that in 1999-2004 NHANES data 20.8% of people aged 6 to 49 had mild or very mild dental fluorosis and 2.0% moderate fluorosis. (Source 5)

• Official position, Certainty not rated.
• Size: NHANES 1999-2004 clinical exam data.
• Who: US population aged 6 to 49.
• How long: lifetime exposure during tooth formation.
• Result: 20.8% mild or very mild, 2.0% moderate, under 1% severe; any fluorosis peaked at 40.6% in adolescents aged 12 to 15.
• Funding: government body.

Analysis of 1999–2004 NHANES clinical exam data showed that 20.8% of people age 6 to 49 had mild or very mild dental fluorosis, 2.0% had moderate fluorosis, and less than 1% had severe fluorosis.

At 0.7 mg/L of fluoride in water, Cochrane's earlier analysis estimated about 12% of people had dental fluorosis of aesthetic concern and about 40% fluorosis of any level. (Source 6)

• Systematic review, Low certainty.
• Size: 40 studies, 59,630 participants for fluorosis of aesthetic concern; 90 studies, 180,530 for any level.
• Who: populations exposed to different water fluoride concentrations.
• How long: chronic exposure.
• Result: about 12% fluorosis of aesthetic concern (95% CI 8% to 17%) and about 40% any fluorosis (95% CI 35% to 44%) at 0.7 ppm; other adverse effects very uncertain.
• Funding: not stated.

Limit of this finding: These fluorosis figures are older than the rest of the review, which is why the quote attributes them to "the last version of the review". The review states that its evidence on fluoridated water and dental fluorosis is current only to February 2015, while its evidence on tooth decay is current to August 2023. So the 12% and 40% estimates describe the fluorosis literature as it stood roughly a decade before the decay figures they sit next to, and they were not re-searched for this update.

If water contains 0.7 mg/L of fluoride, about 12% of people may have dental fluorosis that causes them to be bothered about how their teeth look, and about 40% of people may have dental fluorosis of any level.

What the evidence supports

In permanent teeth, fluoride supplements reduced decayed, missing and filled surfaces by 24% compared with no supplement. (Source 7)

• Systematic review, Low certainty.
• Size: 7,196 children across 11 studies; the no-supplement comparison rests on 3 studies.
• Who: children under 16 at trial entry, mainly school-age.
• How long: minimum follow-up of 2 years.
• Result: 24% reduction in D(M)FS (95% CI 16 to 33%); effect on deciduous teeth unclear.
• Funding: not stated.

In permanent teeth, when fluoride supplements were compared with no fluoride supplement (three studies), the use of fluoride supplements was associated with a 24% (95% confidence interval (CI) 16 to 33%) reduction in decayed, missing and filled surfaces (D(M)FS).

What the evidence does not support

Cochrane found no differential effect of fluoride supplements compared with topical fluorides, and rated the trials as weak evidence. (Source 8)

• Systematic review, Low certainty.
• Size: 11 studies, 7,196 children; 10 rated unclear risk of bias, 1 high.
• Who: children under 16 at trial entry.
• How long: minimum follow-up of 2 years.
• Result: no differential effect on permanent or deciduous teeth versus topical fluorides; effect on deciduous teeth unclear.
• Funding: not stated.

When compared with the administration of topical fluorides, no differential effect was observed. We rated 10 trials as being at unclear risk of bias and one at high risk of bias, and therefore the trials provide weak evidence about the efficacy of fluoride supplements.

Cochrane reviewers judged that in children who already use fluoride toothpaste regularly, the effect of fluoride supplements would probably be limited, and that no conclusion could be drawn for children under six. (Source 1)

• Systematic review, Low certainty.
• Size: 11 studies, 7,196 children.
• Who: children, split above and below 6 years of age.
• How long: minimum follow-up of 2 years.
• Result: no usable estimate for children under 6 with deciduous teeth; benefit in older children arose in trials predating widespread topical fluoride.
• Funding: not stated.

Many of the studies included in the review had been conducted at a time when topical fluorides were not widely used. There is thus a lack of evidence from the review to make actual good recommendations. Today, the effect of fluoride supplements in children using fluoride toothpastes on a regular basis would probably be limited.

Where the evidence is mixed

The same meta-analysis states the drinking-water dose-response data below 1.5 mg/L were limited and uncertain. (Source 9)

• Meta-analysis, Low certainty.
• Size: 74 studies.
• Who: children.
• How long: prenatal and postnatal.
• Result: association remained inverse below 1.5 mg/L in urine and in low risk-of-bias drinking-water studies, but was null at less than 1.5 mg/L in the full drinking-water analysis.
• Funding: not stated in the abstract.

There were limited data and uncertainty in the dose-response association between fluoride exposure and children's IQ when fluoride exposure was estimated by drinking water alone at concentrations less than 1.5 mg/L.

The 2024 Cochrane review of water fluoridation found only a small contemporary benefit, low-certainty, and smaller than in pre-1975 studies. (Source 10)

• Systematic review, Low certainty.
• Size: 157 studies in total, all non-randomised; the contemporary dmft estimate rests on 2 studies and 2,908 children.
• Who: children in communities starting or stopping water fluoridation.
• How long: caries measured within three years of the change and at end of follow-up.
• Result: mean difference in change in dmft 0.24 (95% CI -0.03 to 0.52; P = 0.09), about one-quarter of a tooth, low-certainty, including the possibility of no benefit.
• Funding: not stated.

Limit of this finding: The review switches its plus-and-minus convention part-way through this same paragraph, so the sign of the number cannot be read as the direction of the effect. The dmft result quoted here is a positive mean difference of 0.24 that the review describes as in favour of fluoridation, while two other results a few lines later are negative mean differences (-0.04 and -0.03) that the review also describes as favouring fluoridation. Go by the review's own plain-English gloss instead: a difference of about one-quarter of a tooth, on an estimate that in its own words "includes the possibility of benefit and no benefit".

Based on contemporary evidence (after 1975), the initiation of CWF may lead to a slightly greater change in dmft over time (mean difference (MD) 0.24, 95% confidence interval (CI) -0.03 to 0.52; P = 0.09; 2 studies, 2908 children; low-certainty evidence).

Where the research disagrees

whether fluoride at the concentrations used in public water supplies poses a neurodevelopmental risk

• Taylor and colleagues, JAMA Pediatrics meta-analysis of 74 studies, meta-analysis: This systematic review and meta-analysis found inverse associations and a dose-response association between fluoride measurements in urine and drinking water and children's IQ across the large multicountry epidemiological literature. (Source 9)
• NIH Office of Dietary Supplements, position: Severe enamel fluorosis is rare and there is no indication that it is caused by the recommended level of fluoride in public tap water. (Source 5)

whether the benefit of systemic fluoride still holds now that fluoride toothpaste is near-universal

• Tubert-Jeannin and colleagues, Cochrane review of fluoride supplements, systematic-review: Today, the effect of fluoride supplements in children using fluoride toothpastes on a regular basis would probably be limited. (Source 1)
• Iheozor-Ejiofor and colleagues, 2024 Cochrane review of water fluoridation, systematic-review: Studies conducted in 1975 or earlier showed a clear and important effect on prevention of tooth decay in children. However, due to the increased availability of fluoride in toothpaste since 1975, it is unlikely that we will see this effect in all populations today. (Source 11)

How much

• Reference intake: The Food and Nutrition Board of the National Academies set Adequate Intakes rather than RDAs for fluoride, because it judged the data insufficient to derive Estimated Average Requirements. NIH ODS states the AIs were set from intakes shown to maximise caries reduction without unwanted side effects such as dental fluorosis. The numeric AI values in the ODS table (4 mg/day for men and 3 mg/day for women aged 19 and over) could not be captured as a verbatim sentence and are reported here as table values only. (Source 12)
• Upper limit: The Food and Nutrition Board set a Tolerable Upper Intake Level for fluoride, which ODS defines as the maximum daily intake unlikely to cause adverse health effects; the ODS table gives 10 mg/day for ages 19 to 51 and over. Separately, ODS reports one estimate that the acute dose causing serious systemic toxicity is 5 mg/kg. (Source 12)
• Studied: The Cochrane review pooled trials of fluoride given as lozenges, tablets or liquids, with a minimum follow-up of two years; it did not report a single common dose. (Source 13)
• Studied: In the 1980 poison-centre series, the sodium fluoride preparations in homes contained 0.5 to 1.0 mg of fluoride per dosage unit, and most ingestions were under 1 mg/kg elemental fluoride. (Source 4)

A common belief, and what the research shows

The belief: A fluoride tablet or drop does the same job as fluoride toothpaste, or does it better because it works from inside.

What the research shows: Cochrane found the opposite of an advantage: "When compared with the administration of topical fluorides, no differential effect was observed. We rated 10 trials as being at unclear risk of bias and one at high risk of bias, and therefore the trials provide weak evidence about the efficacy of fluoride supplements." The review also notes that topical action is now considered the more important route: "Today, posteruptive (topical) preventive effect of fluoride is considered as being more important than the pre-eruptive (systemic) effect."

Questions and answers

What is it?

Fluoride is the ionic form of the element fluorine, a mineral present in trace amounts in soil, water, plants and foods. NIH ODS states it inhibits or reverses the initiation and progression of tooth decay and stimulates new bone formation. Dietary fluoride supplements are a small product category, usually sodium fluoride, sold as lozenges, tablets or liquid drops. (Source 14)

What does it do in the body?

Swallowed fluoride is absorbed efficiently from the gut, and in adults about half of what is absorbed is retained, almost all of it in bones and teeth, with the rest excreted in urine. In young children up to 80% is retained because growing bones and teeth take up more. That retention during tooth formation is both how systemic fluoride was thought to protect teeth and how excess causes dental fluorosis. (Source 14)

Is it good or bad for you?

Context decides. Cochrane found supplements reduced decay in the permanent teeth of school-age children compared with no supplement, but judged the underlying trials weak, found no advantage over topical fluoride, and reached no conclusion for children under six. Excess fluoride during tooth formation causes fluorosis, and a 2025 meta-analysis found an inverse association with children's IQ. So the balance depends on age, on how much fluoride a child already gets from water and toothpaste, and on dose. (Source 8)

How do you get more of it?

According to NIH ODS, most of the fluoride people consume comes from fluoridated water, foods and drinks made with fluoridated water, and toothpaste and other dental products. Only a small number of dietary supplements contain fluoride, usually as sodium fluoride, in lozenge, tablet or liquid form. This describes the sources studied, not a recommendation. (Source 14)

If it is harmful, what reduces it?

Fluoride already absorbed is stored in bone and teeth and cleared slowly in urine, so there is no way to strip it out; what changes is intake. Cochrane's 2024 review looked at communities that stopped adding fluoride to water and could not tell whether decay changed. Dental fluorosis, once enamel has formed, is permanent, which is why exposure during tooth formation is the point at which intake matters. (Source 11)

Why might someone be low in it or missing it?

Low fluoride exposure mostly reflects where someone lives and what they use: water that is not fluoridated or naturally low in fluoride, and not brushing with a fluoride toothpaste. Cochrane records that supplements were introduced precisely for areas without water fluoridation, and that additional fluoride sources were considered when daily brushing with fluoride toothpaste is not happening or caries risk is high. (Source 13)

Which whole foods contain it or feed it?

Very little fluoride comes from food itself. ODS states soil, water, plants and foods contain trace amounts, and that most of what people consume arrives through fluoridated water and foods and drinks prepared with it. Brewed tea is the notable exception among ordinary foods because the tea plant concentrates fluoride. (Source 14)

What happens if you do not have it?

The consequence studied is more tooth decay, not a deficiency disease. In the Cochrane comparison against no supplement, children given fluoride supplements had 24% fewer decayed, missing and filled permanent tooth surfaces, 95% CI 16 to 33%. That was measured largely before fluoride toothpaste was widespread, so it overstates what a child already using fluoride toothpaste would lose. (Source 7)

How can you test for it?

There is no validated routine clinical test of an individual's fluoride status. Research studies measure fluoride in drinking water and in urine, and the 2025 IQ meta-analysis used urinary fluoride as its individual-level exposure measure, but that is an exposure marker for populations rather than a diagnostic test. Dental fluorosis is assessed by visual dental examination, as in the NHANES surveys. (Source 2)

We searched: Cochrane CD007592 and CD010856, the NIH ODS fluoride fact sheet, and the JAMA Pediatrics 2025 meta-analysis; none describes a validated individual clinical test, and we could not capture the ODS sentence on fluoride status assessment as part of a contiguous passage.

References

1. Cochrane Database of Systematic Reviews. Fluoride supplements (tablets, drops, lozenges or chewing gums) for preventing dental caries in children (plain language summary, findings). 2011. PMID 22161414, DOI 10.1002/14651858.CD007592.pub2. Read the source
2. JAMA Pediatrics. Fluoride Exposure and Children's IQ Scores: A Systematic Review and Meta-Analysis. 2025. PMID 39761023, DOI 10.1001/jamapediatrics.2024.5542. Read the source
3. NIH Office of Dietary Supplements. Fluoride: Fact Sheet for Health Professionals (Health Risks from Excessive Fluoride, acute toxicity and skeletal fluorosis). undated web page, accessed 2026-09-30. Read the source
4. The Journal of Family Practice. Toxicity Related to Acute Low Dose Sodium Fluoride Ingestions. 1980. Read the source
5. NIH Office of Dietary Supplements. Fluoride: Fact Sheet for Health Professionals (Health Risks from Excessive Fluoride, dental fluorosis). undated web page, accessed 2026-09-30. Read the source
6. Cochrane Database of Systematic Reviews. Water fluoridation for the prevention of dental caries (plain language summary, unwanted effects and confidence). 2024. PMID 39362658, DOI 10.1002/14651858.CD010856.pub3. Read the source
7. Cochrane Database of Systematic Reviews. Fluoride supplements (tablets, drops, lozenges or chewing gums) for preventing dental caries in children (Main results). 2011. PMID 22161414, DOI 10.1002/14651858.CD007592.pub2. Read the source
8. Cochrane Database of Systematic Reviews. Fluoride supplements (tablets, drops, lozenges or chewing gums) for preventing dental caries in children (Authors' conclusions). 2011. PMID 22161414, DOI 10.1002/14651858.CD007592.pub2. Read the source
9. JAMA Pediatrics. Fluoride Exposure and Children's IQ Scores: A Systematic Review and Meta-Analysis (Conclusions and Relevance). 2025. PMID 39761023, DOI 10.1001/jamapediatrics.2024.5542. Read the source
10. Cochrane Database of Systematic Reviews. Water fluoridation for the prevention of dental caries (Main results). 2024. PMID 39362658, DOI 10.1002/14651858.CD010856.pub3. Read the source
11. Cochrane Database of Systematic Reviews. Water fluoridation for the prevention of dental caries (plain language summary, what we found). 2024. PMID 39362658, DOI 10.1002/14651858.CD010856.pub3. Read the source
12. NIH Office of Dietary Supplements. Fluoride: Fact Sheet for Health Professionals (Recommended Intakes). undated web page, accessed 2026-09-30. Read the source
13. Cochrane Database of Systematic Reviews. Fluoride supplements (tablets, drops, lozenges or chewing gums) for preventing dental caries in children (plain language summary, background on routes of fluoride). 2011. PMID 22161414, DOI 10.1002/14651858.CD007592.pub2. Read the source
14. NIH Office of Dietary Supplements. Fluoride: Fact Sheet for Health Professionals (Introduction). undated web page, accessed 2026-09-30. Read the source