Vitamin B6 is the collective name for pyridoxine, pyridoxal and pyridoxamine and their phosphate esters; pyridoxine is the alcohol form found in plants.
What published studies and recent community write-ups report about amounts, timing and course length. 3 clinical and 1 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
| Context | Dose | Frequency | Route | Course | Source |
|---|---|---|---|---|---|
| Clinical3 rows | |||||
| Recommended intakes and upper limit (NIH reference)General population; the RDA covers 97-98% of healthy people | RDA 1.3 mg a day for adults 19-50, 1.7 mg (men) or 1.5 mg (women) over 50, 1.9 mg in pregnancy and 2.0 mg in lactation; upper limit 100 mg a day for adults | Daily intake from food and supplements combined | Oral | LifelongNot applicable | Office of Dietary Supplements, National Institutes of Health2023 |
| The Food and Nutrition Board set the 100 mg upper limit by halving the average 200 mg a day that patients had taken for up to five years without neuropathy, because sensory neuropathy has been reported at doses below 500 mg a day and chronic intakes of 1-6 g a day for 12-40 months cause severe, progressive neuropathy with ataxia. In 2023 the European Food Safety Authority set a far lower upper limit of 12 mg a day for adults. The fact sheet also records that isolated deficiency is uncommon and that supplements are absorbed as well as food, with excess quickly lost in urine. | |||||
| Prescription injection label (pyridoxine hydrochloride 100 mg/mL)Adults with pyridoxine deficiency when oral dosing is not feasible; isoniazid-induced deficiency or poisoning; vitamin B6 dependency syndromes | 10-20 mg a day for dietary deficiency; 100 mg a day for isoniazid-induced deficiency, then 30 mg a day; up to 600 mg a day in dependency syndromes; 4 g intravenously then 1 g intramuscularly every 30 minutes for isoniazid poisoning | Daily; the poisoning regimen gram for gram with the isoniazid ingested | Intramuscular or intravenous | 3 weeks for deficiency, followed by oral multivitamins containing 2-5 mg a day for several weeks; lifelong 30 mg a day in dependencyNot applicable | DailyMed, National Library of Medicine2024 |
| This FDA-approved label (ANDA 080618, first marketed 1972) shows how concentrated medical pyridoxine is: one millilitre carries 100 mg, a hundred times the research solution sold here. It warns that pyridoxine antagonises levodopa given without carbidopa, that dependence symptoms have followed 200 mg a day, that paresthesia and somnolence have been reported, and that 25 mg/kg is well tolerated acutely while 3-4 g/kg kills animals. | |||||
| Nausea and vomiting of pregnancy and premenstrual syndrome (trial doses summarised by NIH)Pregnant women with nausea; women with premenstrual syndrome | 30-75 mg a day in two placebo-controlled pregnancy trials; 10-25 mg three or four times a day as recommended by ACOG; 80 mg a day over three cycles in a 94-woman PMS trial | Daily, or three to four times a day | Oral | Through the symptomatic weeks of early pregnancy; three menstrual cycles in the PMS trialNot described | Office of Dietary Supplements, National Institutes of Health2023 |
| Oral pyridoxine reduced nausea in two randomised trials but a Cochrane review could not reach firm conclusions, and combining it with doxylamine cuts nausea and vomiting by about 70%. The PMS literature is small and methodologically weak. The fact sheet notes that these doses approach the 100 mg upper limit and that pregnant women should consult a physician first; all of this is oral dosing in specific patient groups. | |||||
| Community-reported1 row | |||||
| Vendor liquid format | 1 mg/mL in a 20 mL vial (20 mg total); no dose stated | Not stated | Not stated; the vendor disclaimer excludes oral, injection and self-administration use | Not statedNot stated | Community resource2026 |
| A vendor claim. The certificate for lot B601 identified the content as pyridoxine at 1.11 mg/mL with 99.56% purity by HPLC. One millilitre holds less than the adult RDA of 1.3 mg, so the whole vial is roughly two weeks of dietary requirement and a hundredth of the strength of the prescription injection; the vendor sells the product for cofactor and amino acid metabolism research and does not specify whether the free base or the hydrochloride is in solution. | |||||
Plus 1 community resource (a dosing guide, forum thread or vendor write-up), reported above but not linked.
Vitamin B6 is the collective name for pyridoxine, pyridoxal and pyridoxamine and their phosphate esters; pyridoxine is the alcohol form found in plants and used in most supplements and injections, usually as pyridoxine hydrochloride. Its active coenzyme pyridoxal 5'-phosphate takes part in more than 100 enzyme reactions, mostly in amino acid and neurotransmitter metabolism, the adult RDA is 1.3-1.7 mg a day, and the tolerable upper intake level is 100 mg a day because long-term high doses cause a sensory neuropathy. Prescription injections are 100 mg/mL and are used for deficiency, isoniazid toxicity and pyridoxine-dependent seizures; the research solution sold here is 1 mg/mL, so a full 20 mL vial holds 20 mg, and the vendor's own disclaimer excludes injection and supplementation.
These themes describe recurring questions in published research. They are not claims of effectiveness or recommendations for use.
Energy balance, body composition and incretin signaling.
The Food and Nutrition Board set the 100 mg upper limit by halving the average 200 mg a day that patients had taken for up to five years without neuropathy, because sensory neuropathy has been reported at doses below.
This FDA-approved label (ANDA 080618, first marketed 1972) shows how concentrated medical pyridoxine is: one millilitre carries 100 mg, a hundred times the research solution sold here. It warns that pyridoxine.
Oral pyridoxine reduced nausea in two randomised trials but a Cochrane review could not reach firm conclusions, and combining it with doxylamine cuts nausea and vomiting by about 70%. The PMS literature is small and.
A vendor claim. The certificate for lot B601 identified the content as pyridoxine at 1.11 mg/mL with 99.56% purity by HPLC. One millilitre holds less than the adult RDA of 1.3 mg, so the whole vial is roughly two weeks.
Study models remain visible so laboratory and animal findings are not mistaken for established human outcomes.
3 protocol rows on this page come from human trials, trial registrations, regulator labels or reviews of human data. Approval status and populations are stated per row.
1 row record what blogs, vendor write-ups or forums describe for Vitamin B6. None has been verified against primary literature.
Sequence, synonyms and registry identifiers as recorded in PubChem, the National Library of Medicine's open chemistry database. Formula, mass and CAS number are summarized at the top of the page.
Pyridoxine, Pyridoxol, Vitamin B6, Adermine, Pyridoxinum, UNII KV2JZ1BI6Z, CHEBI:16709
LXNHXLLTXMVWPM-UHFFFAOYSA-N
4,5-bis(hydroxymethyl)-2-methylpyridin-3-ol
4 curated references, each with its journal, year and study model, plus 1 community resource reported but not linked.