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Vitamin B6 (Pyridoxine) — The Complete Supplement Guide

Essential for neurotransmitters and amino-acid metabolism — and the one water-soluble vitamin genuinely toxic in excess. Forms, uses and the nerve-damage limit.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsVitaminsB6 PyridoxineWater-soluble

One of the few water-soluble vitamins where more is not safer — sustained high doses can damage nerves, so the upper limit genuinely matters. For the short dietary version, see the Vitamins page.

Read first. Long-term high-dose B6 causes peripheral nerve damage (numbness, unsteadiness) — the one water-soluble vitamin that is truly toxic in excess. Stay well under the upper limit. Information, not a prescription.

Key takeaways

  • One of the few water-soluble vitamins that harms in excess — sustained high doses damage nerves.
  • Adults need ≈ 1.3–1.7 mg/day.
  • Keep near the upper limit (12–25 mg EFSA / 100 mg US) — more is not better.

Function

Vitamin B6 (as PLP) is a coenzyme in over 100 reactions:

  • Amino-acid metabolism: the central coenzyme for building and breaking down amino acids and protein.
  • Neurotransmitters: makes serotonin, dopamine and GABA — hence links to mood and the nervous system.
  • Haemoglobin: needed to build the haem in red blood cells (deficiency causes anaemia).
  • Homocysteine: with folate and B12, helps clear homocysteine from the blood.
  • Immune & hormone function: supports immune activity and steroid-hormone signalling.

Different forms — and which to choose

Pyridoxine HClThe common, cheap supplement form (converted to the active form in the body).
P5P (pyridoxal-5'-phosphate)The active coenzyme form; preferred by some, especially where conversion may be impaired.

Absorption in the body

How muchWell absorbed; converted in the liver to the active PLP form (a step needing riboflavin).

Deficiency symptoms

SymptomsAnaemia, dermatitis, cracked lips, low mood and irritability, weakened immunity; seizures in infants.
Who's at riskHeavy alcohol use, some medications (e.g. isoniazid), kidney disease and pregnancy.

Recommended intake

Adults ≈ 1.3–1.7 mg/day

Reference intakes:

  • Adults: ~1.3 mg (rising to ~1.5 ♀ / 1.7 ♂ over age 50)

Best sources: poultry, fish, potatoes, bananas, chickpeas and fortified cereals.12

Therapeutic use

Pregnancy nausea10–25 mg (often with doxylamine) is a first-line treatment for morning sickness.
MedicalGiven with the TB drug isoniazid to prevent nerve damage; sometimes used for PMS.

Therapeutic doses

Therapeutic: 10–25 mg (short courses)
EverydayDiet covers needs; keep any supplement modest.
Watch the totalAdd up B6 across multivitamins/B-complex/energy products — it's easy to exceed the limit unknowingly.

Toxicity & upper limit

UL: 12–25 mg (EFSA) · 100 mg (US)
Upper limit12–25 mg/day (EFSA) or 100 mg/day (US).1
Nerve damageChronic high doses cause peripheral neuropathy — numbness, tingling and an unsteady gait, which may only partly reverse.

Bottom line: B6 comes easily from poultry, fish, potatoes and bananas. Short courses (10–25 mg) help pregnancy nausea, but B6 is the water-soluble vitamin you can actually overdose on — tally it across all your supplements and keep well under the limit.

← All supplementsShort dietary version

References

Reference and upper-limit values are general adult figures from official bodies; individual needs vary. Therapeutic doses describe clinical/research use, not prescriptions.

  1. US NIH Office of Dietary Supplements. Vitamin B6 — Health Professional Fact Sheet (function, forms, intakes, food sources, deficiency, therapeutic uses, upper limit, interactions). ods.od.nih.gov
  2. EFSA. Dietary Reference Values & Tolerable Upper Intake Levels for vitamins (European reference intakes and ULs). efsa.europa.eu

This article summarizes nutrition science from official health authorities and peer-reviewed sources for education. It is not a substitute for individual medical advice, and the doses given are not prescriptions — always consult a professional before therapeutic supplement use, in pregnancy, or alongside medication.

✓
Bodil Isaksson, Licensed Biomedical Scientist (Sweden)

At Food Health Lab we explain what the science says in plain language, and we cite our sources so you can check for yourself.

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