tuneTypical Dose
25-50 mg P5P
Vitamin
Vitamin B6
Pyridoxine / Pyridoxal-5'-phosphate (P5P)
Evidence TierAWADA NOT PROHIBITED
watchEffect Window
Acute (days) for nausea. 4-8 weeks for homocysteine.
check_circleCompliance
WADA NOT PROHIBITED
Overview
Clinical Summary
Vitamin B6 is a cofactor for neurotransmitter synthesis and amino acid metabolism. It is used to correct deficiency, support PMS symptom relief, and contribute to homocysteine metabolism alongside folate and B12.
B6 correction improves deficiency-related anemia, dermatitis, and neuropathy symptoms. The best-supported supplemental use cases are pregnancy-related nausea, selected PMS symptom support, and homocysteine-lowering protocols with folate and B12. Chronic high doses can cause sensory neuropathy, so the safety boundary matters as much as the benefit story.
Coenzyme in over 100 reactions. Essential for neurotransmitter synthesis (serotonin, dopamine, GABA) and homocysteine metabolism.
Outcomes
What This Is Expected To Influence
Primary Outcomes
- First-line treatment for pregnancy nausea
- Lowers homocysteine with B9/B12
Secondary Outcomes
- Modest PMS symptom reduction
- Enhanced dream recall
Safety
Contraindications and Interactions
Contraindications
- Pre-existing peripheral neuropathy
- Chronic use >100 mg/day without monitoring
Side effects
- Nausea at high doses
- Photosensitivity (rare)
- Peripheral neuropathy at chronic high doses
Interactions
- Levodopa (reduced efficacy without carbidopa)
- Phenytoin/phenobarbital (may reduce levels)
Avoid if
- Existing neuropathy symptoms
- Levodopa monotherapy without carbidopa
Evidence
Study-level References
vitamin-b6-SRC-001Clinical practice guideline
Sourceopen_in_newACOG Practice Bulletin on Nausea and Vomiting of Pregnancy. American College of Obstetricians and Gynecologists.
Population: Pregnant women with nausea/vomiting
Key findings: Pyridoxine (vitamin B6) is recommended as first-line pharmacotherapy for pregnancy-related nausea.
Paper content
Pyridoxine (vitamin B6) is recommended as first-line pharmacotherapy for pregnancy-related nausea.
vitamin-b6-SRC-002Meta-analysis of randomized controlled trials
Sourceopen_in_newHomocysteine Lowering Trialists' Collaboration. "Lowering blood homocysteine with folic acid based supplements." BMJ. 1998.
Population: Adults with elevated homocysteine
Key findings: Folic acid-based supplements (with B6 and B12) effectively lower homocysteine. B6 contributes incremental benefit beyond folate alone.
Paper content
Folic acid-based supplements (with B6 and B12) effectively lower homocysteine; B6 contributes incremental benefit beyond folate alone.
vitamin-b6-SRC-003Case series
Sourceopen_in_newGdynia HJ, Müller T, Sperfeld AD, et al. "Severe sensorimotor neuropathy after intake of highest dosages of vitamin B6." Neuromuscul Disord. 2008.
Population: Individuals with chronic high-dose B6 use
Key findings: Chronic mega-dosing of pyridoxine causes dose-dependent sensory neuropathy. Some cases showed incomplete recovery after discontinuation.
Paper content
Chronic mega-dosing of pyridoxine causes dose-dependent sensory neuropathy; some cases showed incomplete recovery after discontinuation.
vitamin-b6-SRC-004Multicenter randomized clinical trial.
Sourceopen_in_newReyes-Alvarez MT, Chavez Minano V, Garro-Barrera B, et al. Hydroxocobalamin, thiamine, and pyridoxine as an adjunct to standard treatment in chronic low back pain: a randomized clinical trial. Med Clin (Barc). 2026. doi:10.1016/j.medcli.2025.107307. PMID:41604864.
Population: Patients with chronic mechanical low back pain across six Peruvian centers.
Dose protocol: Injectable B vitamins (B12, B1, B6) as adjunct to NSAIDs for chronic low back pain
Key findings: 84% of the B-vitamin group achieved 30% or greater pain reduction versus 64% in the NSAID-only group.
Notes: Combination formulation limits attribution to B6 alone. Supports B-vitamin adjunctive use for musculoskeletal pain.
Paper content
This multicenter randomized trial across six Peruvian centers tested injectable B vitamins (B12, B1, and B6) as an adjunct to standard NSAID treatment in chronic mechanical low back pain. The B-vitamin group had a significantly higher responder rate, with 84% achieving at least 30% pain reduction compared to 64% in the NSAID-only group. This supports the long-standing use of combined B vitamins for neuropathic and musculoskeletal pain, with pyridoxine (B6) contributing to the combination through its role in neurotransmitter synthesis and nerve function. The injectable route and combination formulation make it difficult to isolate the specific contribution of B6 alone.
vitamin-b6-SRC-005Meta-analysis of randomized controlled trials.
Sourceopen_in_newGuo L, Shi X, Wang G, et al. Combined B-vitamin supplementation on homocysteine and vascular outcomes in coronary heart disease: a meta-analysis. Ann Med. 2026. doi:10.1080/07853890.2026.2622208. PMID:41615824.
Population: Patients with coronary heart disease across 13 RCTs totaling 14,539 participants.
Dose protocol: Combined B-vitamin supplementation (B6, B9, B12) versus controls in 13 RCTs with 14,539 CHD patients
Key findings: Homocysteine reduced by 2.36 umol/L. Vascular restenosis reduced (RR 0.65). No significant MACE or mortality benefit.
Notes: Reinforces that B-vitamin homocysteine lowering is reliable but does not consistently reduce hard cardiovascular events.
Paper content
This meta-analysis of 13 RCTs with 14,539 coronary heart disease patients examined the effects of combined B-vitamin supplementation (including B6, B9, and B12) on homocysteine and vascular outcomes. Combined B vitamins significantly reduced homocysteine by 2.36 umol/L and lowered vascular restenosis incidence (RR 0.65). However, major cardiovascular events and mortality were not significantly different between groups. This reinforces the established finding that B-vitamin-driven homocysteine lowering is biochemically reliable but does not consistently translate to hard cardiovascular event reduction, while suggesting a possible specific benefit for restenosis prevention.
vitamin-b6-SRC-006Systematic review and meta-analysis
Sourceopen_in_newJayawardena R, Majeed S, Sooriyaarachchi P, Abeywarne U, Ranaweera P. The effects of pyridoxine (vitamin B6) supplementation in nausea and vomiting during pregnancy: a systematic review and meta-analysis. Arch Gynecol Obstet. 2023;308(4):1075-1084. doi:10.1007/s00404-023-06925-w. PMID:36719452.
Population: Pregnant women with nausea and vomiting during pregnancy.
Dose protocol: Systematic review and meta-analysis of pyridoxine-alone and pyridoxine-combination trials in pregnancy nausea.
Key findings: Pyridoxine-based interventions improved Rhode's and PUQE nausea and vomiting scores.
Notes: Best modern synthesis for the pregnancy-nausea claim. It supports symptom improvement without implying universal symptom resolution.
Paper content
This meta-analysis strengthens pyridoxine's modern pregnancy-nausea footing. Across 18 studies, vitamin B6 alone and vitamin B6 combinations improved nausea and vomiting scores. It supports keeping pyridoxine as a practical first-line option while avoiding claims that it fully resolves all pregnancy nausea.