Vitamins. Coenzyme
ATC code: A11HA02 (Pyridoxine (vitamin B6))
Brand names – supplements
NOW Foods Vitamin B-6, Solgar B-6 100 mg
Supplements are not tested in clinical trials and are not registered as medications.
Pyridoxine (vitamin B6) is phosphorylated in the body to the active form pyridoxal-5-phosphate (PLP), a cofactor for more than 100 enzymes mainly in amino acid metabolism: transaminases, decarboxylases (neurotransmitter synthesis: GABA, serotonin, dopamine, noradrenaline), and glycogen phosphorylase. Participates in haem and sphingomyelin synthesis. At pharmacological doses (above 200 mg daily) prolonged use causes dose-dependent sensory neuropathy.
First line
Pyridoxine 10–25 mg up to 4 times daily alone or with doxylamine (Diclegis/Bonjesta) is first-line for nausea and vomiting of pregnancy. 2018 recommends pyridoxine as initial pharmacotherapy after dietary measures fail. Cochrane 2015 showed clinically meaningful symptom reduction. Safe for the foetus and mother at doses up to 200 mg daily.
First line
Pyridoxine 50–500 mg daily is the only disease-modifying therapy for the rare autosomal recessive pyridoxine-dependent epilepsy (ALDH7A1 mutations). A trial intravenous pyridoxine 100 mg with concurrent EEG monitoring is both diagnostic and therapeutic for resistant neonatal seizures. Therapy is lifelong. Brain 2021 provides international guidance.
Used in specialised paediatric neurology centres with confirmed genetic diagnosis.
First line
Pyridoxine 25–100 mg daily is first-line for confirmed vitamin B6 deficiency in adults. In patients on isoniazid (drug-induced neuropathy prevention): 25–50 mg daily concurrent pyridoxine. In patients on penicillamine, hydralazine, or cycloserine: similar doses. In infants with pyridoxine-dependent epilepsy: high-dose lifelong therapy.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
An old Cochrane review (1999) showed a weak effect of pyridoxine 50–100 mg daily on PMS symptoms. Newer systematic reviews have not confirmed clinically meaningful effects. does not include pyridoxine in first-line PMS therapy. Standard therapy: oral contraceptives, luteal-phase SSRIs, lifestyle change. High-dose pyridoxine for PMS carries neuropathy risk with prolonged use.
Not recommended
Vitamin B6 (pyridoxine) is a water-soluble vitamin. Its clinical indications are prevention and treatment of B6 deficiency, isoniazid-induced neuropathy, and some rare diseases. In anti-aging regimens, vitamin B6 is sold to slow aging, extend life, and support cognitive function. No clinical studies of prophylactic B6 use in healthy adults for anti-aging exist; international guidelines do not include vitamin B6 as an anti-aging agent. High-dose B6 (above 100 mg/day chronically) can paradoxically cause sensory neuropathy (numbness and tingling in the extremities, described by Schaumburg 1983) – one of the few vitamin toxicities with genuine neurological consequences. If vitamin B6 is being taken in high doses for anti-aging, consider seeking a second opinion.
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FDA category A at physiological doses. Use of 10–25 mg four times daily for nausea and vomiting of pregnancy is safe and encouraged by ACOG. Doses above 100 mg daily long-term in pregnancy are not recommended.
Transfers into breast milk at physiological amounts. Supplementation at the RDA is safe. High doses can suppress lactation – not recommended.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Pyridoxine (vitamin B6) is evaluated for the following indications with varying evidence strength: Vitamin B6 (pyridoxine) deficiency (evidence tier A), Nausea and vomiting of pregnancy (evidence tier A), Pyridoxine-dependent epilepsy (evidence tier A). See the full indication matrix with dosing and citations above on this page.
Common side effects of Pyridoxine (vitamin B6) (≥ 1 in 100): Allergic reactions (urticaria, pruritus), Skin rash. See the Safety section for uncommon and serious reactions.
FDA category A. FDA category A at physiological doses. Use of 10–25 mg four times daily for nausea and vomiting of pregnancy is safe and encouraged by ACOG. Doses above 100 mg daily long-term in pregnancy are not recommended.
Transfers into breast milk at physiological amounts. Supplementation at the RDA is safe. High doses can suppress lactation – not recommended.
Pyridoxine (vitamin B6) is contraindicated in: Hypersensitivity to pyridoxine; Severe ischaemic heart disease (for high-dose parenteral administration); Active peptic ulcer disease (relative). Full list in the Safety section.
the effect on the nervous system in non-deficient patients is not confirmed. The hypnotic-sedative claim in supplement marketing lacks scientific basis.
doses above 200 mg daily long-term (more than 6 months) cause sensory neuropathy. Cases are reported at 100 mg daily over more than a year. This is the most dangerous vitamin with uncontrolled use.
newer systematic reviews have not confirmed an effect. Standard PMS therapy: oral contraceptives, luteal-phase SSRIs, CBT – not B6.