Vitamin B6 (Pyridoxine)
Pyridoxine
TL;DR
Vitamin B6 supports neurotransmitter synthesis and homocysteine clearance. Useful at 10–50 mg/day; sustained high doses cause reversible nerve damage.
Ideal For
- Pregnant women with nausea, under clinical guidance
- People on isoniazid, penicillamine or hydralazine
- Those with elevated homocysteine alongside folate and B12
- People with chronic kidney disease or malabsorption
Avoid If
- You already take a high-dose B-complex — doses stack easily above safe levels
- You have existing peripheral neuropathy
- You take levodopa without carbidopa
Frequently Asked Questions
Overview
Vitamin B6 exists in several forms that converge on pyridoxal 5-phosphate, the active coenzyme for more than 140 enzymatic reactions. Most involve amino acid metabolism, including the decarboxylation steps that produce serotonin, dopamine and GABA, and the transsulfuration pathway that clears homocysteine.
Frank deficiency is uncommon but appears in chronic kidney disease, alcohol use, coeliac disease and with isoniazid, penicillamine or long-term oral contraceptive use. Supplementation has decent evidence in a few specific settings: nausea and vomiting of pregnancy, where 10-25 mg three or four times daily is a first-line treatment often paired with doxylamine; premenstrual symptoms, where doses up to 100 mg/day showed benefit in older trials; and homocysteine lowering alongside folate and B12.
The safety point deserves emphasis because it is unusual for a water-soluble vitamin. Sustained intake above roughly 200 mg/day, and in some case series far less taken for years, causes a sensory peripheral neuropathy with numbness and unsteadiness. It usually improves after stopping but recovery can take months and is occasionally incomplete. B6 is one of the few vitamins where more is genuinely worse.
How It Works
- As pyridoxal 5-phosphate, a coenzyme for over 140 enzymes, mostly in amino acid metabolism
- Required for decarboxylation of 5-HTP to serotonin and L-DOPA to dopamine
- Cofactor for cystathionine beta-synthase in homocysteine clearance
- Needed for glutamate decarboxylase, which produces GABA
- Supports haem synthesis via ALA synthase
Quick Facts
- Involved in 100+ enzymatic reactions
- Essential for neurotransmitter production
- Supports immune system function
- Critical for hemoglobin formation
- May help reduce PMS symptoms
Benefits & Outcomes
Mood Stabilization
Evidence for B6 alone improving mood is weak outside of deficiency or PMS-related symptoms.
Cognitive Function
B6 lowers homocysteine but has not been shown to protect or improve cognition on its own.
Hormonal Balance
B6 has modest evidence for premenstrual symptoms; broader hormonal claims are not supported.
Immune Function
Adequate B6 is required for normal lymphocyte function, but supplementation in replete people offers no demonstrated immune benefit.
Health Concerns Addressed
No linked health concerns yet.
Supporting Research8 studies
Efficacy of vitamin B-6 in the treatment of premenstrual syndrome: systematic review
Wyatt KM, Dimmock PW, Jones PW +1 more
Pooled odds ratio favoured vitamin B-6 over placebo for overall premenstrual symptoms, though included trials were of low methodological quality.
Superiority of magnesium and vitamin B6 over magnesium alone on severe stress in healthy adults with low magnesemia: A randomized, single-blind clinical trial
Pouteau E, et al.
the addition of vitamin B6 to Mg was not superior to Mg supplementation alone.
Effects of vitamin B6 (pyridoxine) and a B complex preparation on dreaming and sleep
Adventure-Heart DJ, et al.
We found that vitamin B6 significantly increased the amount of dream content participants recalled but did not significantly affect dream vividness, bizarreness, or color.
Vitamin B6-Induced Neuropathy: Exploring the Mechanisms of Pyridoxine Toxicity
Hadtstein F, Vrolijk M
Chronic high-dose pyridoxine intake is associated with dose-dependent sensory peripheral neuropathy; case reports exist below previously assumed safe thresholds.
Effect of Combined Use of Calcium and Vitamin B6 on Premenstrual Syndrome Symptoms: a Randomized Clinical Trial
Masoumi SZ, et al.
using of combination of calcium and vitamin B6 leads to better controlling of the premenstrual syndrome symptoms.
A synergistic effect of a daily supplement for 1 month of 200 mg magnesium plus 50 mg vitamin B6 for the relief of anxiety-related premenstrual symptoms: a randomized, double-blind, crossover study
De Souza MC, Walker AF, Robinson PA +1 more
A small synergistic effect of a daily dietary supplementation with a combination of Mg + vitamin B6 in the reduction of mild premenstrual anxiety-related symptoms was demonstrated during treatment of 44 women for one menstrual cycle.
A prospective study of the intake of vitamins C and B6, and the risk of kidney stones in men
Curhan GC, Willett WC, Rimm EB +1 more
These data do not support an association between a high daily intake of vitamin C or vitamin B6 and the risk of stone formation, even when consumed in large doses.
Using pyridoxine to treat carpal tunnel syndrome: randomized control trial
Spooner GR, Desai HB, Angel JF +2 more
Our findings do not support the use of pyridoxine for treating carpal tunnel syndrome.
Safety Information
Potential Side Effects
Nausea and headache at higher doses. The important adverse effect is a dose- and duration-dependent sensory peripheral neuropathy — tingling, numbness, unsteady gait — from sustained high intake, usually but not always reversible on stopping.
Contraindications
Do not exceed 100 mg/day long term without medical supervision because of sensory neuropathy risk. Plain levodopa without a decarboxylase inhibitor is a genuine interaction — B6 accelerates its peripheral breakdown.
Drug Interactions
- Levodopa without carbidopa — B6 reduces its effectiveness
- Phenytoin and phenobarbital — B6 can lower serum levels
- Isoniazid, penicillamine, hydralazine and cycloserine — these deplete B6, which is why supplementation is often prescribed
- Amiodarone — additive photosensitivity reported
Pregnancy & Breastfeeding
Pregnancy: safe
Breastfeeding: likely_safe
Dosage Guidelines
Dosage Used in Studies
10-50 mg
Best Time to Take
With breakfast or the evening meal
Best Form
Pyridoxal 5-phosphate at modest doses, since it bypasses hepatic conversion
Bioavailability
P5P is active form. Pyridoxine HCl requires conversion. Water-soluble vitamin. High doses (>200mg/day) long-term associated with neuropathy risk.
Forms Compared
Pyridoxine hydrochloride
Pyridoxal 5-phosphate (P5P)
Pyridoxamine
Food & Timing
With food; taking it on an empty stomach can cause nausea
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.