While the risk varies between individuals, consumption of high doses of vitamin B6 has been linked to peripheral neuropathy—a form of nerve damage presenting with numbness, prickling or tingling in feet, hands or arms, which can lead to muscle weakness and motor function impairment. If left untreated, the damage can be permanent.
Pharmacovigilance reports from several countries suggest that cases of vitamin B6 toxicity have increased in recent years. In the United States, for example, the Food and Drug Administration’s Human Foods Complaint System (HFCS) recorded 98 serious adverse events involving vitamin B6 products between 1999 and 2025, including 39 reports in 2024 alone.
Although passive reporting systems have well-known limitations, serious adverse events linked to vitamin B6 appear to be rare. Even so, the growing number of cases have led regulators in countries including Australia and Canada to strengthen consumer protections, a move that has drawn criticism from segments within the dietary supplement industry.
Toxicity concerns and strengthening regulations
Found in foods such as pork, poultry, peanuts, oats and bananas, vitamin B6 is a water-soluble vitamin that comes in six forms. Most vitamin B6 supplements contain the biologically inactive form pyridoxine, which is metabolized into pyridoxal-phosphate (PLP) inside the body to become active.
The vitamin is essential for making hemoglobin, a protein that carries oxygen through the blood and helps produce neurotransmitters, release energy from food, regulate hormonal activity and support the immune system. As such, it is considered an essential vitamin, with the recommended dietary allowance (RDA) for adults averaging between 1.3 and 1.7 mg per day.
Vitamin B6 toxicity has never been reported from food sources alone, only from excessive or long-term intake of supplements or prescription medicines. While it has received increased attention in recent years, vitamin B6 toxicity is not a new phenomenon.
Severe sensory peripheral neuropathy in individuals following ingestion of large doses of vitamin B6 was first described in the early 1980s after a study by Schaumburg et al. identified vitamin B6-related peripheral neuropathy at very high doses of around 2 to 6 grams a day.
In 1987, a study by Dalton and Dalton found that symptoms consistent with sensory nerve damage were present in humans at much lower doses (around 50 mg per day), with signs of toxicity observed after an average of 35 months.
As a result, in 1997, the UK’s Committee on Toxicity recommended a maximum daily intake of 10 mg per day of vitamin B6 from dietary supplements to account for real-world uncertainties.
The Dalton and Dalton study has been criticized on methodological grounds, primarily because it relied on self-reported data and lacked objective neurological testing. Despite these limitations, the UK regulatory body opted to act on these reported risks, mandating that B6 products containing 11 mg to 49 mg must be sold as pharmacy-only products.
Not long after, several countries conducted their own toxicology assessments to establish safe upper intake levels (ULs). The United States set a 100 mg UL in 1998, followed by the European Union with a 25 mg limit in 2000. In 2008, Australia’s Therapeutic Goods Administration (TGA) required warning labels on products delivering over 50 mg per dose.
Stricter recommendations then followed in Australia and the European Union, with the EU cutting the UL to 12 mg per day in 2023 and Australia requiring warnings on products containing 10 mg of B6 in 2025.
The TGA has now also licensed products containing between 50 mg and 200 mg of vitamin B6 as pharmacist-only after its Database of Adverse Event Notifications (DAEN) linked 250 reports of peripheral neuropathy, peripheral sensory neuropathy, peripheral sensorimotor neuropathy, small fiber neuropathy, polyneuropathy and chronic polyneuropathy to vitamin B6 products between 2023 and 2025.
Concerns over conclusions and unintended consequences
Canada is the most recent country to increase its oversight of vitamin B6 supplements, updating its monograph for vitamin B6-containing natural health products in March following a review that identified a possible association between high doses of vitamin B6 and peripheral neuropathy.
Health Canada also now expects license holders to add warnings to product labels containing 10 mg of vitamin B6 or more.
Sonia Parmar, vice president of government relations and regulatory affairs at the Canadian Health Food Association (CHFA), said this ‘precautionary approach’ raises broader concerns about how Health Canada is choosing to regulate certain supplements.
“[Health Canada’s] conclusion is based on a limited number of cases, with significant uncertainty, incomplete clinical information and confounding factors—it does not establish causality or quantify real-world risk,” she said, noting that the outcome also highlights questions around consistency.
“Health Canada’s own review indicates that prescription vitamin B6 products were not subject to the same update and that supplemented foods were outside the scope of the review and are being assessed separately. Clear and consistent explanations for these differences will be important to maintain confidence in the regulatory approach.”
The Council for Responsible Nutrition (CRN) has also raised concerns about how regulatory bodies have come to their conclusions about the safe level of vitamin B6. The organization has suggested a UL of 100 mg, and Andrea Wong, CRN’s senior vice president and chief science officer, noted that setting the limit too low could also pose a risk to consumers.
“Evidence from credible, well-designed human studies consistently shows that neuropathy associated with vitamin B6 supplementation only occurs at substantially higher intake levels—typically above 200 mg per day, and often much higher,” she said. “EFSA’s 2023 UL of 12 mg per day relied heavily on a controversial study from 1987 that has raised questions about the validity of its results, as well as a study conducted in dogs, applying large uncertainty factors to both studies.”
Wong added that while the CRN recognizes that regulators in different jurisdictions may apply different precautionary approaches, regulatory decisions should be based on the strength and quality of evidence and that the available clinical data do not support the conclusion that low doses pose a meaningful neuropathy risk for the general population.
“Setting low ULs that are not grounded in up-to-date, relevant science is concerning,” she said. “When ULs are set excessively low relative to the available evidence, there is a risk that products formulated to address legitimate nutritional needs could become unavailable or reformulated to levels that may be less effective. This could create unintended public health consequences, particularly for individuals who may benefit from higher supplemental intakes under appropriate guidance.”
What does the science say?
A limited number of human studies have explored peripheral neuropathy resulting from vitamin B6 consumption. While the 1983 Schaumburg study was the first to identify cases of vitamin B6-related peripheral neuropathy at doses of 2 to 6 grams a day, the Dalton and Dalton study is the most widely known, given that symptoms were reported at doses as low as 50 mg.
Several studies in rats and dogs have also found that pyridoxine injections cause gait abnormalities, sensory dysfunction and coordination impairment. However, these studies typically use extremely high doses, equivalent to hundreds or thousands of milligrams per day in humans.
Many regulatory bodies have also used case reports to determine dosing recommendations. For example, the Netherlands Pharmacovigilance Centre Lareb reported 238 cases of nerve damage linked to vitamin B6–containing products from August 2007 to July 2024. In total, 79 cases involved a product with a daily dose of 12 mg or less. However, only 15% of the variability in the reported plasma levels could be explained by the daily dose.
In its report, Lareb noted that long-term use is likely to play a role in the development of peripheral neuropathy, primarily because pyridoxine accumulates in plasma after chronic use. However, latency varied from ‘right after start’ to 23 years of use, suggesting other factors may be at play.
Research also suggests that the form, or ‘vitamer’, of B6 may influence the development of neuropathy. Pyridoxine has been linked to adverse events, and some researchers have proposed that supplements containing pyridoxal-phosphate (the active form) may be less likely to cause peripheral neuropathy than those containing pyridoxine.
This evidence suggests that while high-dose vitamin B6 supplementation carries a clear risk, there is no established, universally applicable dose known to causes peripheral neuropathy, leading regulatory bodies to adopt more conservative dosing recommendations.
Anna VerMeer, senior clinical toxicologist and pharmacovigilance officer at SafetyCall International, said adverse events are more likely to occur when multiple B6-containing products are consumed. She also highlighted that given the hundreds of millions of vitamin B6-containing supplements, the total number of reported adverse events represents a very small proportion of total exposures.
“The problem may arise in increased daily doses from product stacking: A person taking a multivitamin, a B-complex supplement and 1 to 2 energy drinks a day,” she said.
Consumers are therefore advised to check the supplement facts and nutrition labels on supplements and energy drinks to monitor their total daily vitamin B6 intake.
“This is a nutrient used safely by millions of people every day, but the emerging adverse event data, both domestically and internationally, points to a need for further investigation,” VerMeer added.
