It is well established that fluoride ingestion can cause a range of gastrointestinal (“GI”) symptoms, including nausea, pain, and vomiting. It is not yet understood, however, what level of fluoride in the stomach is necessary to cause these symptoms, and how much this level varies based on the sensitivity of the individual. In 2006, the National Research Council called for more research to explore these issues.

Individuals with High Exposures to Fluoride

It is well known that humans with high levels of fluoride ingestion can suffer significant and persistent gastric problems. Humans suffering from skeletal fluorosis, for example, have been repeatedly observed to suffer high rates of GI disorders. When fluoride intake is reduced among these patients, the gastrointestinal problems are among the first symptoms to disappear. Similarly, when high doses of fluoride (18-34 mg/day) have been used as an experimental drug to treat osteoporosis, gastric disturbances are one of the two main side effects consistently encountered.

Ingestion of Fluoride Toothpaste

Each year there are thousands of reports to Poison Control Centers throughout the United States due to excessive ingestion of fluoride toothpaste and other fluoridated dental products. GI symptoms are generally the first symptoms that a person (usually a child) will experience. A review of reports to Poison Control Centers in Utah found that vomiting was induced in children after ingestion of just 5 to 9 mg of fluoride.

Because GI symptoms caused by fluoride toothpaste ingestion mimic common GI problems, people experiencing gastric distress from fluoride toothpaste may not realize the source of their problem.  As noted in the Journal of Public Health Dentistry:

“Parents or caregivers may not notice the symptoms associated with mild fluoride toxicity or may attribute them to colic or gastroenteritis, particularly if they did not see the child ingest fluoride. Similarly, because of the nonspecific nature of mild to moderate symptoms, a physician’s differential diagnosis is unlikely to include fluoride toxicity without a history of fluoride ingestion.” SOURCE: Shulman JD, Wells LM. (1997). Acute fluoride toxicity from ingesting home-use dental products in children, birth to 6 years of age. Journal of Public Health Dentistry 57: 150-8.

Fluoride damages gastric mucosa at relatively low doses

A single ingestion of as little as 3 mg of fluoride, in carefully controlled clinical trials, has been found to produce damage to the gastric mucosa in healthy adult volunteers. No research has yet been conducted to determine the effect of lower doses with repeated exposure.

Fluoride-Sensitive Individuals

Among adults, double-blind studies have found that single doses of 6.8 mg of fluoride can induce vomiting, and other gastric symptoms, within 30 minutes. Among children, gastrointestinal ailments have been found to occur in about 1% of kids ingesting 1 mg fluoride tablets. Although 1 mg of fluoride in tablet form produces a more toxic effect on the gastric tract than 1 mg of fluoride from fluoridated water (due to the diluting effect of the water), some case studies have found that hypersensitive individuals experience GI effects by drinking fluoridated water.

NRC Says More Research Is Needed

In 2006, the National Research Council called for more research to examine the GI effects of low-dose fluoride exposure. According to the NRC:

“The numerous fluoridation studies in the past failed to rigorously test for changes in GI symptoms and there are no studies on drinking water containing fluoride at 4 mg/L in which GI symptoms were carefully documented.”

The NRC thus stated that:

“Studies are needed to evaluate gastric responses to fluoride from natural sources at concentrations up to 4 mg/L and from artificial sources.”

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