I saw some news articles on the internet arguing that having too much vitamin B6, such as a supplement that contains too much vitamin B6, can be bad for one’s health. While I place exactly zero credence in the argument of most popular media, especially when it comes to dietary science and interpreting scientific studies, I thought this was worth a closer look.

Take-home message:

  • Too much vitamin B6 can cause health problems. It’s unclear exactly what the best upper limit is. The evidence base isn’t super strong.
  • EFSA recommends 12 mg/day as an upper limit for the general adult population, based on a plausible and cautious reading of the available scientific studies. Schellack et al recommends 50 mg/day as an upper limit for patients being treated for peripheral neuropathy.

EFSA Panel on Nutrition et al 2023, EFSA Journal, link

  • “Systematic reviews of the literature were conducted”
  • “The relationship between excess vitamin B6 intakes and the development of peripheral neuropathy is well established and is the critical effect on which the UL is based.”
  • “A lowest-observed-effect-level (LOAEL) could not be established based on human data. A reference point (RP) of 50 mg/day is identified by the Panel from a case–control study, supported by data from case reports and vigilance data. An uncertainty factor (UF) of 4 is applied to the RP to account for the inverse relationship between dose and time to onset of symptoms and the limited data available. […] This leads to a UL of 12.5 mg/day.”
  • [another study from Beagle dogs?]
  • “From the midpoint of the range of these two ULs and rounding down, a UL of 12 mg/day is established by the Panel for vitamin B6 for adults (including pregnant and lactating women).”

Schellack et al 2025, Expert Consensus on Vitamin B6 Therapeutic Use for Patients: Guidance on Safe Dosage, Duration and Clinical Management, Drug, Healthcare and Patient Safety, link

  • “Statement 1: Vitamin B6 and its metabolites are essential for the functioning of the nervous system, as a coenzyme for metabolic reactions that is crucial for synthesis of neurotransmitters such as γ-aminobutyric-acid (GABA), dopamine, epinephrine and serotonin.” (Strength of Recommendation: 9.8/10)
  • “Statement 2: Vitamin B6 deficiency may result in peripheral neuropathy, seborrheic dermatitis, microcytic anaemia, dental decay, glossitis, seizures, depression, confusion and weakened immune function.” (Strength of Recommendation: 9.2/10)
  • “Statement 3: Clear dose and duration recommendations associated with neuropathy aetiology, patient risk groups, or symptoms severity have not been established. Clinicians should carefully evaluate each patient’s individual condition when deciding dosage and duration. Based on published literature and expert clinical practices, the following tolerable (maximum) daily dosage and associated duration of vitamin B6 intake is recommended for peripheral neuropathy as shown in Table 2.” [Table 2 essentially recommends 50 mg as possible for long-term use] (Strength of Recommendation: 8.3/10)
  • For context tot he above: “The recommended dietary allowance (RDA) for adults at different life stages averages between 1.3–1.7 mg per day, which is an amount generally achievable through adequate food intake.”
  • “Statement 4: Vitamin B6-induced neurological adverse events have been reported in high therapeutic dose and long-term usage. However, these are generally rare and may be reversible upon treatment cessation when recognized early. Early detection of adverse events is key to management of neurological adverse events.” (Strength of Recommendation: 9.2/10)
  • “Statement 5: For patient usage duration of longer than 6 months, and over 50 mg/day vitamin B6, regular monitoring by healthcare professionals is recommended. If patients develop neurological side effects, a washout period of 20 ~ 40 days (3 ~ 6 weeks) is recommended before considering resuming vitamin B6 treatment.” (Strength of Recommendation: 7.3/10)

Vrolijk et al 2017, The vitamin B6 paradox: Supplementation with high concentrations of pyridoxine leads to decreased vitamin B6 function, Toxicology in Vitro, link

  • “Recently, the European Food Safety Authority (EFSA) has established an upper limit (UL) of 25 mg/day. This UL was based on neurological complaints observed after taking 50 mg of pyridoxine per day. This [new limit] is 4 times lower than the previous UL of 100 mg/day of USDA and other authorities.”
  • “Paradoxically, supplementation of vitamin B6 has also been shown to lead to polyneuropathy. Already in 1987, a case of polyneuropathy after supplementation of a high dose of vitamin B6 was reported. In the years that followed, more cases on vitamin B6 toxicity were reported. Recently, The Netherlands Pharmacovigilance Centre Lareb, which collects and analyses reports of adverse reactions of medicines and vaccines, published a report concerning the side effects of vitamin B6 supplements. Since 2014, > 50 cases of sensory neuronal pain due to vitamin B6 were reported to Lareb. The dose of vitamin B6 differed from 1.5–100 mg.”
  • “People chronically taking vitamin B6 supplements reported complaints such as pain in the extremities and muscle weakness. These complaints were reversible as they faded away after stopping the supplementation. Most often, these complaints were seen when taking mega doses (> 50 mg/day) of vitamin B6 for a longer period of time. However, recently, Lareb reported cases in which lower doses (2 mg/day) of vitamin B6 gave the same complaints.”
  • “In conclusion, the present study strongly indicates that the neuropathy observed after taking a relatively high dose of vitamin B6 supplements is due to the vitamer that is used in the supplements, namely pyridoxine. The inactive form pyridoxine competitively inhibits the active pyridoxal-phosphate. As a consequence, the paradox arises that the symptoms of vitamin B6 supplementation are similar to those of vitamin B6 deficiency.”
  • “The question is whether lowering the safe dose for vitamin B6 is the solution. Remarkably, even at relatively low dose, vitamin B6 supplementation has given rise to complaints.”
  • “Our study indicates that the toxicity of vitamin B6 is not only determined by the dose, but by the vitamer in which it is taken. Perhaps it might be better to replace pyridoxine by pyridoxal or pyridoxal-phosphate as vitamin B6 supplements, which are much less toxic.”