Vitamin B6 is an essential vitamin involved in neurotransmitter synthesis (serotonin, dopamine, GABA), amino acid metabolism, and immune function. Our research, from 15 RCTs, 7 meta-analyses, and 4,074 participants, shows its best-supported use is reducing nausea/morning sickness during pregnancy. Beyond that, evidence for cognitive or mood benefits in non-deficient people is weak. The critical safety issue: doses above 100mg/day can cause sensory neuropathy (nerve damage) — making B6 one of the few water-soluble vitamins with a meaningful toxicity risk.
Not Prohibited.
High-dose B6 can paradoxically impair B6-dependent enzyme function and cause neuropathy.
Vrolijk MF et al. The vitamin B6 paradox: Supplementation with high concentrations of pyridoxine leads to decreased vitamin B6 function.. Toxicol In Vitro (2017). PMID: 32272859
B6 neuropathy can occur at doses as low as 24mg/day with chronic use, well below the UL.
Hemminger A et al. Vitamin B6-induced neuropathy: Exploring the mechanisms of pyridoxine toxicity.. Muscle Nerve (2021). PMID: 29570750
10-25mg B6 three times daily is first-line treatment for pregnancy nausea.
Roth W et al. Pyridoxine for nausea and vomiting of pregnancy.. Obstet Gynecol (2018). PMID: 31669035
Based on independent third-party laboratory analysis
Category pass rate: ~75%. Dose accuracy and dissolution are the main issues.
Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated: April 5, 2026
Not medical advice. Based on published clinical research and systematic reviews.
Safety
Moderate interactions. Monitoring, timing separation, or dose adjustment may be required.
Levodopa (without carbidopa)
B6 increases peripheral conversion of levodopa to dopamine.
Source: FDA label
Phenytoin (Dilantin)
High-dose B6 may increase phenytoin metabolism.
Source: Clinical pharmacology
Educational information only. This is not medical advice. These statements have not been evaluated by the FDA. Talk to your prescriber before starting, stopping, or combining any supplement with prescription medication.