Evidence-based·Last reviewed May 31, 2026·How we grade evidence

Vitamin B6 (pyridoxine)

VitaminVitamin B6

The inactive supplemental form of vitamin B6 that the liver converts to the active coenzyme PLP. Cheapest, most widely tested form — used in every major clinical guideline (ACOG NVP, Wyatt PMS). Strong evidence for correcting deficiency and as first-line therapy for pregnancy nausea. The unique caveat: chronic high doses cause sensory neuropathy, and EFSA (2023) now caps the safe daily limit at 12 mg.

Quick decision guide

May help most

Pregnant women with morning sickness (10–25 mg, 3–4×/day per ACOG), people on B6-depleting drugs (isoniazid, cycloserine), and correcting documented B6 deficiency.

Common dosing range

1.3–2.0 mg/day RDA from diet; 10–100 mg/day for clinical indications (PMS, NVP, deficiency).

When to expect effects

Days to weeks for NVP; weeks for PMS; weeks for biomarker correction in deficiency.

Watch out for

Don't take >100 mg/day long-term without a clinician — sensory neuropathy is dose-dependent. EFSA now uses a 12 mg/day ceiling.

Evidence snapshot

Correcting B6 deficiencyStrong
Pregnancy nausea (NVP)Moderate
Premenstrual symptomsEmerging
Lowering homocysteineModerate
Reducing cardiovascular eventsLow
Pyridoxine vs P5P superiorityLow

What is it

Pyridoxine is the most common supplement form of vitamin B6, used to support amino acid metabolism, red blood cell formation, and neurotransmitter synthesis. The body converts it to the active coenzyme pyridoxal 5-phosphate.

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You're pregnant with nausea/vomiting — ACOG recommends pyridoxine 10–25 mg up to 4×/day as first-line therapy
You have PMS, especially mood-related symptoms — Wyatt 1999 supports doses up to 100 mg/day
You take isoniazid, cycloserine, levodopa, or hydralazine — these drugs deplete B6
You're correcting documented B6 deficiency (CKD, IBD, alcohol use disorder, post-bariatric)
You want the cheapest, most-studied form — pyridoxine HCl is in every major clinical trial

Probably skip if…

You're already getting B6 from food (chickpeas, tuna, banana, chicken)
You want to take >100 mg/day daily for general wellness — neuropathy risk outweighs benefit
You take levodopa for Parkinson's WITHOUT carbidopa — pyridoxine blunts its effect
You're hoping high-dose B6 will prevent heart attacks — large CV trials negative
You're convinced you need the active P5P form — bioavailability difference doesn't reliably translate to clinical outcomes

Evidence at a glance

Correcting B6 deficiency

Strong Evidence
Effect
Normalizes plasma PLP within 2–6 weeks at 10–50 mg/day
Best fit
Adults with CKD, IBD, alcohol use disorder, post-bariatric surgery, or on isoniazid / cycloserine / hydralazine / penicillamine
Time
Weeks for biomarker correction

Nausea and vomiting of pregnancy (NVP)

Good Evidence
Effect
Significant reduction in nausea score; combination with doxylamine ~70% reduction vs placebo
Best fit
Pregnant women with mild-to-moderate morning sickness
Time
Days to 1–2 weeks

Lowering homocysteine

Good Evidence
Effect
Reliable homocysteine reduction in combination with folate + B12; HOPE-2 showed ~25% stroke reduction; most other large CV trials negative
Best fit
People with documented hyperhomocysteinemia or homocystinuria
Time
Weeks for biomarker; years for any hard endpoint

Premenstrual syndrome (PMS)

Limited Evidence
Effect
OR 2.32 for overall symptom improvement (Wyatt 1999); modest effect sizes in newer single trials
Best fit
Women with PMS featuring mood symptoms (irritability, low mood, anxiety)
Time
1–3 menstrual cycles

Evidence for 4 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Correcting B6 deficiency

Corrects deficiency
Strong Evidence

Pyridoxine reliably raises plasma PLP and corrects clinical deficiency. RDA: 1.3 mg/day for adults 19–50; 1.7 mg/day (men 51+), 1.5 mg/day (women 51+). People at elevated deficiency risk include chronic kidney disease, IBD, alcohol use disorder, and patients on B6-antagonist drugs (isoniazid, cycloserine, hydralazine, penicillamine). Standard correction doses of 10–50 mg/day restore plasma PLP within weeks. Pyridoxine HCl is the form used in every clinical guideline.

Effect size
Normalizes plasma PLP within 2–6 weeks at 10–50 mg/day
Time to effect
Weeks for biomarker correction
Best fit
Adults with CKD, IBD, alcohol use disorder, post-bariatric surgery, or on isoniazid / cycloserine / hydralazine / penicillamine
Less likely
Healthy adults eating a varied diet

Bottom line: Pyridoxine HCl at 10–50 mg/day is the standard, well-evidenced form for deficiency correction.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet

Nausea and vomiting of pregnancy (NVP)

Supplement benefit
Good Evidence

ACOG Practice Bulletin 189 (2018) names pyridoxine 10–25 mg orally 3–4×/day as first-line pharmacotherapy for NVP, alone or combined with doxylamine 12.5 mg (the Diclegis/Diclectin combination). Multiple RCTs show statistically significant reductions in nausea severity; the doxylamine combination shows ~70% reduction in nausea/vomiting versus placebo. Safety data covering hundreds of thousands of pregnancies shows no increase in birth defect risk. The Matthews 2015 Cochrane review found monotherapy evidence less consistent than combination therapy, but ACOG still endorses pyridoxine alone as a safe first step.

Effect size
Significant reduction in nausea score; combination with doxylamine ~70% reduction vs placebo
Time to effect
Days to 1–2 weeks
Best fit
Pregnant women with mild-to-moderate morning sickness
Less likely
Hyperemesis gravidarum — pyridoxine alone is insufficient; needs IV hydration / ondansetron

Bottom line: First-line, ACOG-recommended. Try pyridoxine alone first; add doxylamine if needed.

SourceACOG Practice Bulletin 189, 2018 — Nausea and Vomiting of PregnancyMotherToBaby Diclegis Fact Sheet, 2025 — OTIS / NCBI Bookshelf

Lowering homocysteine

Biomarker support
Good Evidence

Pyridoxine is a cofactor for cystathionine beta-synthase, the enzyme that disposes of homocysteine. B6 + folate + B12 combinations reliably lower plasma homocysteine. The HOPE-2 trial showed a 25% stroke-risk reduction with this triple combination. However, despite reliable biomarker lowering, most large CV outcome trials (VISP, NORVIT, WAFACS) have failed to show clinically meaningful reductions in heart attacks or all-cause mortality.

Effect size
Reliable homocysteine reduction in combination with folate + B12; HOPE-2 showed ~25% stroke reduction; most other large CV trials negative
Time to effect
Weeks for biomarker; years for any hard endpoint
Best fit
People with documented hyperhomocysteinemia or homocystinuria
Less likely
Adults with normal homocysteine hoping to reduce general CV risk

Bottom line: Useful for proven hyperhomocysteinemia. Don't take it as general heart-attack prevention.

Evidence is mixed

Reliable biomarker lowering does not translate into reliable cardiovascular event reduction in most large RCTs.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet· conflicting
SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet

Premenstrual syndrome (PMS)

Supplement benefit
Limited Evidence

The Wyatt 1999 BMJ systematic review pooled 9 RCTs (940 women) and found pyridoxine up to 100 mg/day produced an overall symptom-improvement OR of 2.32 (95% CI 1.95–2.54) and a depressive-symptom OR of 1.69. The authors flagged that most trials were low quality and called for larger, better-designed studies — which haven't really materialized. Recent smaller trials at 80 mg/day report significant improvements in mood symptoms, irritability, and anxiety. Mechanism is plausible (PLP is a cofactor for neurotransmitter synthesis) but causality isn't firmly pinned down.

Effect size
OR 2.32 for overall symptom improvement (Wyatt 1999); modest effect sizes in newer single trials
Time to effect
1–3 menstrual cycles
Best fit
Women with PMS featuring mood symptoms (irritability, low mood, anxiety)
Less likely
Women with primarily physical PMS symptoms (bloating, breast tenderness)

Bottom line: Reasonable to try at ≤50 mg/day for mood-dominant PMS; stop within 3 cycles if no benefit. Don't sit at 100 mg/day indefinitely.

Evidence is mixed

Wyatt meta-analysis is positive but underlying trials are mostly low quality; no large, well-powered RCT has confirmed since. Doses approaching 100 mg/day cross into long-term neuropathy-risk territory.

SourceWyatt et al., 1999 — BMJ — Efficacy of vitamin B-6 in premenstrual syndrome· conflicting
SourceWyatt et al., 1999 — BMJ — Efficacy of vitamin B-6 in premenstrual syndrome

How it works

Pyridoxine is absorbed in the small intestine and phosphorylated by the liver to form pyridoxal 5-phosphate (PLP), the active coenzyme for more than 100 enzymes involved in amino acid metabolism, gluconeogenesis, and the synthesis of neurotransmitters like serotonin, dopamine, and GABA. PLP is also needed for hemoglobin synthesis and conversion of tryptophan to niacin. Most B6 in the body is stored in muscle tissue bound to glycogen phosphorylase. Excess is excreted in urine, though high doses still accumulate in nerve tissue and can cause toxicity.

How to take it

1. Typical dose
• RDA: 1.3 mg/day (adults 19–50), 1.7 mg/day (men 51+), 1.5 mg/day (women 51+) • Pregnancy: 1.9 mg/day; lactation: 2.0 mg/day • NVP: 10–25 mg orally, 3–4 times daily (ACOG) • PMS: 50–100 mg/day (Wyatt 1999); stay at lower end for chronic use • Deficiency correction: 10–50 mg/day for weeks
2. Higher studied dose
Studies have used 100–200 mg/day for PMS and homocysteine; doses above 200 mg/day for months carry tangible neuropathy risk. The 1–6 g/day doses associated with classic megavitamin-B6 syndrome are far above any single supplement dose but are reached when stacking multiple B-complex products.
3. Timing
Take with food to minimize the rare nausea. Time-of-day not critical. If you take levodopa (without carbidopa), pyridoxine accelerates peripheral conversion — don't combine without a neurologist's input.
4. With food
With food.
5. Split dosing
For NVP specifically, ACOG recommends splitting into 3–4 daily doses of 10–25 mg. For deficiency or PMS, a single daily dose is fine.
6. How long to try
NVP: until symptoms resolve (usually weeks of the first trimester). PMS: at least 3 menstrual cycles to assess. Deficiency: until plasma PLP normalizes (4–8 weeks) plus a maintenance period.

What to track

Nausea severity (NVP)
PMS symptom score across 2–3 cycles (mood, irritability, anxiety)
New numbness, tingling, or unsteady gait — STOP supplement immediately
Plasma PLP if testing for deficiency

Bottom line: Stay at ≤50 mg/day unless treating active NVP or under clinician supervision. Discontinue immediately if you notice numbness, tingling, or balance problems.

3 commercial forms

Compare the main delivery options and what they’re best suited for.

Pyridoxine HCl

Most studied

The classic supplemental form — pyridoxine bound to hydrochloride for stability. Requires liver conversion to PLP (the active coenzyme), but this conversion is reliable in healthy adults. Used in essentially every major clinical trial (Wyatt PMS, ACOG NVP guidance, deficiency correction studies). Cheapest form per mg.

Liver-converted to active PLP; reliable in healthy adults.

Pyridoxal-5-phosphate (P5P, PLP)

Active form

The biologically active coenzyme form. Skips liver conversion but is largely dephosphorylated in the intestine to pyridoxal before absorption, then re-phosphorylated. Plasma PLP rises higher per mg dose, but no convincing RCT shows superior clinical outcomes vs pyridoxine HCl in healthy adults. May be preferred in severe liver disease.

Higher peak plasma PLP; clinical outcome advantage not established.

Pyridoxamine

Limited supplement availability

Another natural form of vitamin B6 (alongside pyridoxine and pyridoxal). FDA classified it as a drug in 2009, restricting its sale as a dietary supplement in the US.

Restricted as a supplement in the US.

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

nausea (mild, usually with empty stomach)headache (rare)photosensitivity (very rare, high doses)

Serious risks

Who should avoid it

Pregnancy & breastfeeding

Pyridoxine 10–25 mg three to four times daily is ACOG-recommended first-line therapy for nausea/vomiting of pregnancy. Safety data covering hundreds of thousands of pregnancies (largely via the Diclegis/Diclectin combination) shows no increase in birth defect risk. The pregnancy RDA is 1.9 mg/day. Doses up to 100 mg/day are considered safe in pregnancy short-term; megadoses are not recommended.

SourceACOG Practice Bulletin 189, 2018 — Nausea and Vomiting of PregnancyMotherToBaby Diclegis Fact Sheet, 2025 — OTIS / NCBI Bookshelf

Bottom line: Safe at RDA-equivalent and modest therapeutic doses (10–50 mg/day). Don't take >100 mg/day long-term without a clinician, and stop immediately at the first hint of numbness or tingling.

Interactions

levodopa (without carbidopa)Moderate

Pyridoxine is a PLP cofactor for aromatic L-amino acid decarboxylase; accelerates peripheral conversion of L-dopa to dopamine before it reaches the brain, blunting effect. Modern carbidopa-levodopa combos block this peripheral conversion.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet
isoniazid (INH)Moderate

INH binds and inactivates PLP, causing peripheral neuropathy and seizures. Pyridoxine 10–50 mg/day is routinely co-prescribed with INH to prevent this.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet
cycloserineModerate

Cycloserine increases urinary B6 loss and antagonizes PLP-dependent enzymes; supplementation recommended to prevent neurotoxicity and seizures.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet
hydralazineMinor

Hydralazine can complex with PLP, increasing B6 requirements.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet
penicillamineMinor

Forms inactive complex with PLP; supplementation often recommended.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet
antiepileptics (phenytoin, carbamazepine, valproic acid)Minor

Increase B6 catabolism; can lower plasma PLP and raise homocysteine over time. Very high B6 doses may reduce phenytoin levels.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet
amiodaroneMinor

High-dose pyridoxine may increase amiodarone-induced photosensitivity.

SourceNIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet

Protocols featuring Vitamin B6 (pyridoxine)

Evidence-backed routines where Vitamin B6 (pyridoxine) plays a role.

Trimester 1 Prenatal

maternal

The first trimester is the highest-stakes window of pregnancy nutritionally. Neural tube formation completes by week 4-6 (often before pregnancy is even known), organogenesis is in full swing, and the most common early-pregnancy symptom — morning sickness — affects 70-85% of pregnancies. This protocol covers the four nutritional priorities for trimester 1: a methylfolate-containing prenatal (the single most-evidenced intervention in obstetric nutrition for preventing neural tube defects), vitamin B6 + ginger for nausea (both ACOG-supported as first-line), choline for fetal brain and liver development (commonly under-consumed), and iron when ferritin is confirmed low. This protocol replaces your Fertility Prep — Women stack once pregnancy is confirmed. Many supplements that were fine pre-conception (ashwagandha, vitex, berberine, high-dose vitamin A, certain herbal blends) are contraindicated in pregnancy. Coordinate every supplement with your OB.

PMS Support

hormones

Premenstrual syndrome affects up to 75% of menstruating women in some form. The supplement literature is unusually solid here — magnesium, B6, calcium, and chasteberry each have multiple randomized trials supporting their use for the physical and emotional symptoms of PMS. Effect sizes are real but modest, and the stack works best when taken consistently across the cycle rather than only in the luteal phase. Severe PMS or PMDD warrants a conversation with your doctor — supplements are first-line for mild-to-moderate symptoms, not a substitute for proper care in severe cases.

Food sources

Chickpeas, canned

Amount
1 cup (1.1 mg)
%DV
65%

Beef liver, pan-fried

Amount
3 oz (0.9 mg)
%DV
53%

Tuna, yellowfin, cooked

Amount
3 oz (0.9 mg)
%DV
53%

Salmon, sockeye, cooked

Amount
3 oz (0.6 mg)
%DV
35%

Chicken breast, roasted

Amount
3 oz (0.5 mg)
%DV
29%

Potato, baked with skin

Amount
1 medium (0.4 mg)
%DV
24%

Banana

Amount
1 medium (0.4 mg)
%DV
24%

Cottage cheese, low-fat

Amount
1 cup (0.2 mg)
%DV
12%

Squash, winter, baked

Amount
½ cup (0.2 mg)
%DV
12%

Rice, brown, cooked

Amount
1 cup (0.1 mg)
%DV
6%

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

'Pyridoxine HCl' on the label — the form used in nearly all clinical trials and ACOG guidance
10–25 mg per capsule for NVP use (matches ACOG dosing)
25–50 mg per capsule for general supplementation if correcting marginal intake
Third-party tested (USP, NSF, ConsumerLab) to confirm dose accuracy
Single-ingredient capsule if you want precise dose control — B-complex products vary widely in B6 amount

Be skeptical of…

'200 mg' or higher per capsule marketed for daily long-term use — well into neuropathy-risk territory; EFSA UL is 12 mg/day
Claims that pyridoxine is 'identical to P5P' — pyridoxine IS the inactive form requiring liver conversion
'Energy boost' or 'mood support' marketing on mega-dose B6 — no evidence pyridoxine is energizing in non-deficient people
Combination 'morning sickness' products that pile B6 with herbs of unclear pregnancy safety — stick with plain pyridoxine + doxylamine

Frequently asked questions

How does pyridoxine differ from P5P?⌄

Pyridoxine must be converted by the liver to the active form P5P. Both work for most people; P5P bypasses one conversion step and may be preferable in liver dysfunction.

Can pyridoxine cause nerve damage?⌄

Yes, at chronic doses above 100 to 200 mg per day. The upper limit is 100 mg per day. Stop the supplement and consult a doctor if you develop tingling or numbness.

Is pyridoxine safe in pregnancy?⌄

Yes, at low doses (10 to 25 mg) used for nausea relief. Higher doses should be discussed with your obstetrician.

Should I take pyridoxine with food?⌄

Either way works. Some people take it with breakfast to make it a habit; food does not significantly affect absorption.

References by claim

Correcting B6 deficiency

NIH Office of Dietary Supplements — Vitamin B6 — Health Professional Fact Sheet (2024) link

Safety

EFSA Panel on Nutrition, 2023 — EFSA Scientific Opinion on the Tolerable Upper Intake Level for Vitamin B6 (2023) link

Nausea and vomiting of pregnancy (NVP)

ACOG Practice Bulletin 189, 2018 — Nausea and Vomiting of Pregnancy (2018) link

MotherToBaby Diclegis Fact Sheet, 2025 — OTIS / NCBI Bookshelf (2025) link

Premenstrual syndrome (PMS)

Wyatt et al., 1999 — BMJ — Efficacy of vitamin B-6 in premenstrual syndrome (1999) link

Other references

Vitamin B6 (pyridoxine) on Wikidata — Wikidata link

Pyridoxine (ChEBI:27306) — ChEBI link

Pyridoxine on NIH DSLD — NIH Dietary Supplement Label Database link

Track Vitamin B6 (pyridoxine) with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

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Evidence-based·Last reviewed May 31, 2026·Evidence current as of May 31, 2026·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.