Fluoride
Fluoride is a term many people associate with toothpaste or drinking water. For decades, it has been valued in dentistry as a means of preventing cavities. At the same time, it repeatedly sparks debate when it comes to health risks – especially potential neurotoxic effects. How dangerous is fluoride really? Where is it indispensable, and who actually decides how much of it is allowed in our drinking water?
Since I began my dental studies in 1975, the positive effect of fluoride on teeth and gums has never been in question. The only side effect we knew of was fluorosis, whitish discoloration in permanent teeth caused by excessive fluoride exposure from birth until the age of six. These white spots contain a particularly high concentration of calcium fluoride, which is extremely acid-stable and therefore resistant to cavities.
Based on what we know today, it’s time to reconsider fluoride!
What is fluoride?
Fluoride is the negatively charged ion of the chemical element fluorine. It occurs naturally in various compounds, such as in minerals like fluorite (CaF₂). Fluoride is present in small amounts in water, food, and also in the human body. In medicine—especially dentistry—fluoride is used to specifically combat increased susceptibility to tooth decay.
Fluoride is not essential for life in the classical sense, as is the case with essential nutrients (e.g., iron, calcium, vitamin C). The human body does not require fluoride for vital metabolic processes. There are no known enzymes or biochemical reactions that absolutely require fluoride.
The positive effects of fluoride
Fluoride has been a proven method for preventing tooth decay since the 1950s. This is based, in part, on an ion pump effect. This means that fluoride accelerates the remineralization of tooth enamel when it has lost minerals due to acid attack. The incorporation of particularly acid-resistant calcium fluoride “hardens” the enamel. Furthermore, fluoride inhibits certain enzyme reactions in caries-causing bacteria, thus reducing their activity.
These benefits are well-documented in numerous studies. Especially in children during the mixed dentition phase, the use of fluoride toothpaste and an appropriate fluoride intake can provide long-term protection against tooth decay.
The downsides of fluoride
However, there are also risks. One is the aforementioned dental fluorosis: Excessive intake during tooth development can lead to permanent changes in the tooth enamel – usually in the form of white spots.
Then there is skeletal fluorosis: In regions with very high natural fluoride levels in the water (e.g., parts of India or China), long-term overexposure can lead to hardening of the bones, pain, and restricted movement. Finally, the systemic absorption of fluoride poses another problem. It is not only effective locally in the oral cavity but can also enter the bloodstream via the digestive tract – this carries potential risks, especially with consistently high intake.
A balancing act between benefits and risks
Fluoride is a double-edged sword. When used correctly, it offers effective protection against cavities and is indispensable in modern dentistry. At the same time, current studies show that excessive intake—especially during development—poses potential risks.
Therefore, the current approach seems to be:
- Topical application (e.g., toothpaste) is safe and beneficial when used correctly.
- Systemic intake (e.g., via drinking water or tablets) should be critically reviewed and individually adjusted.
- Special care must be taken with children to avoid fluorosis.
Current scientific findings do not definitively support classifying fluoride as a neurotoxin in general—but they emphasize the need for further research. This should not mean we continue as before. In my opinion, the use of fluoride must therefore be reduced to the absolute, unavoidable minimum.
Fluoride because of bad habits!
We dentists use fluoride to combat an increased susceptibility to cavities. This raises the question: why is our susceptibility to cavities so high that we have to use fluoride?
The central problem is poor nutrition. In many Western countries, the diet is too cariogenic because too much sugar or short-chain carbohydrates, such as wheat or spelt, are consumed too frequently. This, along with obesity, inevitably leads to cavities.
If our society continues to tolerate the pervasiveness of sugar in our food but is only willing to accept a low risk of cavities, then we dentists have to use fluoride. Based on what we know, there’s currently no other way. Period!
… If you don’t want this for yourself, if you don’t want cavities but also don’t want to take fluoride, then follow these recommendations:
- Avoid sugar in any form
- Reduce your carbohydrate intake and consistently avoid wheat (this will be difficult… but it’s possible!)
- Avoid all foods that are advertised
Where we cannot avoid fluoride
There are situations where we dentists cannot avoid using fluoride without causing lasting harm to the patient: This is the problem of insufficient saliva!
As I’ve already explained, a tooth decay attack leads to the loss of ions from the tooth enamel, but this can be reversed if there is enough time and sufficient saliva. The less saliva there is, the longer this remineralization takes. Therefore, people with insufficient saliva have a sometimes exorbitantly high risk of developing cavities.
Insufficient saliva often occurs simply due to aging. However, the much bigger problem is that dry mouth is often a side effect of medication. So, if such medications are prescribed, the doctor should ideally refer the patient to us immediately so that we can adjust their professional prophylaxis. However, in over 40 years of practice, I’ve only experienced this once!
Here is a brief overview of drug classes that can cause dry mouth:
- Anticholinergics inhibit the parasympathetic nervous system. Examples: Atropine, scopolamine, ipratropium (for COPD), oxybutynin (for incontinence)
- Antidepressants, especially tricyclic antidepressants (TCAs) such as amitriptyline, imipramine. SSRIs and SNRIs can also cause dry mouth, such as fluoxetine, sertraline, and venlafaxine.
- Antipsychotics (neuroleptics): Blockade of cholinergic receptors. Examples: haloperidol, olanzapine, clozapine
- Antihistamines (especially older generations) block H1 receptors and have anticholinergic side effects. Examples: diphenhydramine, dimenhydrinate, clemastine
- Antihypertensives. Especially: beta-blockers (e.g., metoprolol, atenolol, bisoprolol, propranolol), diuretics (e.g., hydrochlorothiazide, furosemide), ACE inhibitors (rarely)
- Opioids. Central suppression of saliva production. Examples: Morphine, oxycodone, fentanyl
- Muscle relaxants. Centrally acting agents such as baclofen, tizanidine
- Antiemetics such as metoclopramide or ondansetron
- Medications for incontinence, e.g., darifenacin, tolterodine (anticholinergic effect)
- Medications for Parkinson’s disease, e.g., biperiden, levodopa + benserazide
Is fluoride a neurotoxin?
The debate surrounding fluoride as a neurotoxin was primarily sparked by several studies in recent years. Of particular interest are studies that have established a link between high fluoride intake during pregnancy and reduced intelligence in children.
A widely cited meta-analysis by Harvard researchers from 2012 evaluated 27 studies from China. The result: Children living in regions with high fluoride levels in their drinking water showed, on average, lower IQ scores.
From 2012:
From 2013:
In a study by Veneri et al. The 2023 study states:
“…With increasing urinary fluoride levels above 0.28 mg/L (corresponding to approximately a water fluoride level of 0.7 mg/L), a weaker and largely linear decrease of -2.15 (95% CI -4.48; 0.18) IQ points was observed. The inverse relationship between fluoride exposure and IQ was particularly strong in the studies with a high risk of bias, while no negative effects were observed in the only study with a low risk of bias. Overall, most studies indicated that fluoride exposure has negative effects on children’s IQ even at low exposure levels…”
More recent studies from Canada (2019) and Mexico (2017) showed similar correlations, especially regarding fluoride intake during pregnancy.
Many of these studies have methodological weaknesses. These include, among others, inconsistent fluoride measurement, the exclusion of the influence of other environmental toxins, and the frequent failure to account for socioeconomic factors. Ignored.
As you can see, the data isn’t simply black and white. To avoid turning this into a scientific article, I refer you to the many links below where you can find further information on the topic.
Finally
If there is an increased susceptibility to caries, then broadly speaking, there are only two groups:
- Some are too careless in their diet and thus provoke the development of caries. The solution to the problem lies in changing behavior and eating habits. As we already know, the probability of success with this is low. In this case, we cannot avoid fluorides from an economic perspective.
- Others suffer from dry mouth (e.g., due to medication). This group should visit a dental practice offering professional prophylaxis as soon as possible.
Based on what I believe I know today, fluoride is not indicated beyond this.
Author: drw
If you want to know more about the topic, I recommend the following links:
As you will see, the data is not conclusive. The mere fact that there is a significant probability that fluoride can be neurotoxic in certain doses leads us to an extremely cautious approach to its use.
Fluoride Exposure: Neurodevelopment and Cognition… from 2025
https://ntp.niehs.nih.gov/research/assessments/noncancer/completed/fluoride
‘The science of fluoride is starting to evolve’: behind the risks and benefits of the mineral… from 2024
https://www.theguardian.com/society/2024/nov/27/fluoride-health-benefits-risks?
Fluoride Exposure: Neurodevelopment and Cognition… from 2025
https://www.theguardian.com/society/2024/nov/27/fluoride-health-benefits-risks
Fluoridating Drinking Water… a page with further links:
Is It Time to Rethink Fluoride in Drinking Water? … from 2024
https://www.verywellhealth.com/fluoride-lower-iq-children-report-8708414?
Should we think twice about fluoride? … from 2024
Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis … from 2023:
https://pubmed.ncbi.nlm.nih.gov/36639015/
Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis… from 2025:
https://pubmed.ncbi.nlm.nih.gov/39761023/
Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis… from 2012
https://ehp.niehs.nih.gov/doi/10.1289/ehp.1104912?
A systematic review and meta-analysis of the association between fluoride exposure and neurological disorders… from 2021
https://pmc.ncbi.nlm.nih.gov/articles/PMC8609002/?
Early Childhood Exposures to Fluorides and Cognitive Neurodevelopment: A Population-Based Longitudinal Study… from 2024
https://journals.sagepub.com/doi/full/10.1177/00220345241299352?
Decreased Intelligence in Children and exposure to fluoride and arsenic in drinking water… from 2007
https://www.scielo.br/j/csp/a/q7y9RbrbCGQj9xt5S8GgpRt/?lang=en
Effect of Water Source on Human Health: a Case Study from Biga Peninsula, Turkey… from 2009
https://avesis.deu.edu.tr/publication/details/f5cc96be-1343-4100-9562-15a78054df6b/oai
The Relationship of Dental Fluorosis, Intellectual Efficiency and Working Memory in 13-15-year-olds Living in Low, Medium and High-water Fluoride Areas in Kajiado County… by 2019
https://erepository.uonbi.ac.ke/handle/11295/109635
Effect of fluoride on the learning and memory ability of larvae of Zaprionus indianus… from 2020
https://basicandappliedzoology.springeropen.com/articles/10.1186/s41936-020-00166-y
Ameliorative Potential of Ginger (Zingiber officinale) following Repeated Coexposure with Fluoride and Dimethoate in Blood and Brain of Wistar Rats… from 2024
https://onlinelibrary.wiley.com/doi/10.1155/2024/8815630
Exposure to fluoride and risk of primary bone cancer: A systematic review… by 2025
https://pubmed.ncbi.nlm.nih.gov/39510434/
Association of fluoride exposure with disease burden and neurodevelopment outcomes in children in South Korea… from 2024
https://pubmed.ncbi.nlm.nih.gov/38937407/
Fluoride: From Nutrient to Suspected Neurotoxin… from 2022
https://pubmed.ncbi.nlm.nih.gov/36079765/
Toxicity of fluoride: critical evaluation of evidence for human developmental neurotoxicity in epidemiological studies, animal experiments and in vitro analyses… from 2020
https://pmc.ncbi.nlm.nih.gov/articles/PMC7261729/
Is Fluoride Potentially Neurotoxic… by 2019
https://jamanetwork.com/journals/jamapediatrics/article-abstract/2748626
An in vivo and in silico probing of the protective potential of betaine … from 2024
https://fluoridealert.org/wp-content/uploads/2024/11/owumi-2024.pdf
At the end of the day, it’s the dose that counts—as is so often the case in toxicology. Or, as Paracelsus put it: “All things are poison, and nothing is without poison; the dose alone makes a thing not a poison.”
This article is not a scientific treatise and partly represents my personal opinion on some topics. The numerous links are intended to encourage you to form your own comprehensive opinion.