Vitamin B6

Australia and Canada now put a nerve-damage warning on B6 products from about 10 mg a day, because people developed nerve damage from B6 they did not know they were taking. Food gives you all the B6 you need.

At a glance

Our verdict	Hidden in magnesium, multivitamin, B-complex and energy products; no proven benefit without a deficiency, and the doses add up to a risk of nerve damage in the hands and feet.
Sold for	Energy, nerves, nausea (claimed)
How sure the evidence is	High that very high doses harm the nerves; Low below 50 mg
Cost a month	B6 alone about $3 to $6 (estimated)

Written for adults in Canada. It explains the evidence; it is not advice for you personally. Last reviewed 20 October 2026.

Supplement Check

Is it right for you?

B6 hides in magnesium, multivitamin, “stress” and electrolyte products and in energy drinks. Your check adds up the B6 in everything you take and tells you what to stop. Our Supplement Check looks at:

Tingling, numbness, burning or new unsteadiness while taking anything with B6
Pregnancy: the prescribed doxylamine-pyridoxine product is the route for nausea
Current smokers: no single-vitamin B6 product
Older adults: a true shortfall is more likely with alcohol, kidney or liver disease
Kidney disease on dialysis: kidney vitamins are prescribed by your kidney team
Every medicine you take
The total across everything you already take, against the safe upper limits

Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.

$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check

Tell me when it opens

What it is

A water-soluble vitamin with three forms (pyridoxine, pyridoxal and pyridoxamine) and their phosphates. The active form in the body is pyridoxal 5'-phosphate (PLP). Supplements use pyridoxine hydrochloride (the cheapest and most common) or PLP, sold as “P-5-P” or “active B6”. Most labels give only the chemical name, so people often do not know they are taking it. [1]

Adults need 1.3 to 1.7 mg a day, and food supplies it. B6 is also prescribed: with doxylamine for nausea in pregnancy (Diclectin and generics, 10 mg of B6 a tablet) and in Pregvit (10 mg), [2] and alongside isoniazid for tuberculosis. We do not sell a B6 product.

Structure of Vitamin B6 — Structure: PubChem (public domain).

How it acts

PLP helps over 150 chemical reactions: making serotonin, dopamine, GABA and histamine, making haem for red blood cells, breaking down homocysteine, and turning tryptophan into niacin. [1]

Too much does harm in an unexpected way. In cell studies, excess pyridoxine blocked the active form, so too much B6 behaves like too little: toxicity and deficiency cause the same nerve damage. [3, 4] This is laboratory work and a leading explanation, not proof in people.

Outline of a person showing where Vitamin B6 acts in the body

What it is used for, and what the evidence says

Why Australia acted: by 31 October 2025 its regulator, the Therapeutic Goods Administration, held 250 reports of nerve damage linked to B6 products, 83% of them since 2023 and 130 in 2025 alone. [5] Since 2023 every Australian product over 10 mg a day must carry a warning and none may exceed 100 mg; from 1 June 2027, products giving over 50 mg and up to 200 mg a day will be sold only by a pharmacist. [6, 5] Canada added a warning at 10 mg a day in 2026 but has not restricted sale, and its upper limit is still 100 mg. [2, 7] Europe set its upper limit at 12 mg. [8]

Use	What the trials found	How sure we are
Nausea and vomiting in pregnancy	In 18 studies, pyridoxine alone or combined improved a 15-point nausea score by 0.75 points. [9] The prescribed doxylamine-pyridoxine tablet lowered the score by 4.8 points against 3.9 with placebo. [10] Both effects are under one point on the scale. This is the only use of B6 with trials, and it belongs with the doctor or pharmacist looking after the pregnancy.	Low (B6 alone); moderate (prescribed product)
Heart attack, stroke and death (lowering homocysteine)	B-vitamin combinations lowered stroke a little (4.3% against 5.1% over the trials) and did nothing for heart attack or death. [11] B6 on its own had no effect in the Norwegian trials. [12]	High
Energy, stress and mood	Studied only in combinations, with a small effect on self-rated stress and none on mood or anxiety. See B-complex.	Low
Premenstrual symptoms, carpal tunnel, memory	We found no adequate evidence for any of these. They were not reviewed in depth.	No evidence (no adequate evidence)
Nerve damage at very high doses (harm)	Seven adults taking 2 to 6 g a day developed severe loss of feeling and unsteadiness; all improved after stopping, four were severely disabled. [13] In 16 people taking 0.2 to 5 g a day, the higher the dose, the sooner symptoms began. [14] In five volunteers given 1 or 3 g a day, symptoms kept getting worse for 2 to 3 weeks after stopping (“coasting”), although blood B6 was already normal. [15]	High
Nerve damage at ordinary supplement doses (harm)	In 172 women taking a mean of 117 mg a day, symptoms related to how long they had taken it (2.9 against 1.6 years), not the dose; all recovered within 6 months of stopping. [16] Dutch reports involved products of 1.4 to 100 mg a tablet, and harm below 50 mg a day “cannot be excluded”. [17] After the Netherlands capped supplements at 21 mg a day in 2018, reports fell, but cases at lower doses continue. [18] In Australia, 66% of the 2022 cases with enough detail were at 50 mg a day or less. [6] Against this, the two best controlled studies, of 381 and 261 people with nerve damage of unknown cause, found no link with B6 dose, duration or blood level. [19, 20] Our reading: the risk is real but uncommon and unpredictable at 10 to 50 mg (low certainty), and below 10 mg it is unproven (very low certainty). The 10 mg warnings are precautions, not proven thresholds.	Low
Lung cancer in men who smoke	Men who took single-vitamin B6 over 20 mg a day for 10 years had 1.82 times the risk of lung cancer, highest in smokers. This is one observational study, not proof of cause. [21]	Low (observational)

How sure we are: High means further research is very unlikely to change the answer; Moderate, it might; Low, it may well change; Very low, we are very unsure. These follow the GRADE method that guideline panels use.

Benefits

Nausea in pregnancy, B6 alone: 0.75 points better on a 15-point score; Low
Nausea in pregnancy, prescribed doxylamine-pyridoxine: About 0.9 points more than placebo; Moderate
Stroke (B vitamins combined): 4.3% against 5.1%; High
Heart attack, death: No effect; High
Energy, stress, mood, without a deficiency: No proven benefit; Very low

Risks and side effects

Nerve damage (a sensory neuropathy): tingling, numbness, burning or pain in the hands and feet, or new unsteadiness. Certain at very high doses, and reported at 50 mg a day or less. [6] It usually settles within weeks to 6 months of stopping, [16] can get worse for 2 to 3 weeks first, [15] and severe high-dose cases may be permanent. [13]
Doses that add up without you noticing. B6 is in multivitamins (an age-50+ multivitamin 3 mg, one sport multivitamin 6 mg), in 199 Canadian magnesium products (55% of them give 10 mg or more), in B-complex products (median 50 mg), in one electrolyte product (14 mg), and in Canadian energy drinks (up to 14 mg a day). [22, 23] A multivitamin, a magnesium-B6 product and one energy drink come to 25 to 30 mg without anything labelled “vitamin B6”.
Taking more for the tingling makes it worse, because too much B6 causes the same symptoms as too little. [3, 1]
Labels may not warn you. Only 6% of Canadian B-complex licences at 10 mg or more carry the 2026 nerve warning in their licence record. [22]
Lung cancer signal in men who smoke and take single-vitamin B6 over 20 mg a day for years (observational). [21]

Interactions with medicines

B6 does not speed up or block the liver enzymes (cytochrome P450) that clear most medicines. The medicine interactions below are standard prescribing knowledge and were not re-checked in our review.

Medicine	What can happen	What to do
Phenytoin, phenobarbital	High-dose B6 (about 200 mg a day and over) lowers their levels	No high-dose B6; discuss with your doctor
Levodopa given without carbidopa (rare today)	B6 speeds its breakdown before it reaches the brain	Discuss with your doctor
Isoniazid, cycloserine, hydralazine, penicillamine	They use up B6, so B6 is often prescribed with them	Keep prescribed B6; counted in your total, never stopped by the check
Doxylamine-pyridoxine (Diclectin and generics), Pregvit	Prescribed B6, 10 mg a tablet, up to 40 mg a day	Keep taking as prescribed; we add no other product with B6
Magnesium, multivitamin, B-complex, electrolyte products, energy drinks	The B6 adds up	Counted together; kept under 10 mg a day

Who should not take it

Tingling, numbness, burning or new unsteadiness while taking anything with B6: stop all B6 products and book a consultation. Do not take more B6 for it.
Pregnancy: the prescribed doxylamine-pyridoxine product is the route for nausea; Health Canada found no evidence of nerve harm from the prescription products. [2] Europe's 12 mg limit also applies in pregnancy and breastfeeding. [8]
Current smokers: no single-vitamin B6 product. [21]
Older adults: a true shortfall is more likely with alcohol, kidney or liver disease; measure before treating.
Kidney disease on dialysis: kidney vitamins are prescribed by your kidney team.
Liver disease: ask your doctor first.
Under 18: the limits are lower (Europe 6.1 to 10.7 mg at 7 to 17 years; [8] Health Canada's product maximum 80 mg at 14 to 18 [7]). Outside the Supplement Check.

Dose and timing

We do not sell a B6 product and do not recommend a dose. Adults need 1.3 to 1.7 mg a day, and food supplies it.
Our rule: the total from every product stays under 10 mg a day. We count multivitamins, magnesium, B-complex, electrolyte and “stress” or “energy” products, and energy drinks (14 mg for each daily drink unless the label says less).
On labels look for vitamin B6, pyridoxine, pyridoxal, pyridoxal 5'-phosphate or P-5-P.
B6 your doctor prescribed is counted, and never stopped by the check.
How to tell where you stand: a blood test of PLP. Under 20 nmol/L is deficient, 20 to 30 is low; [24] above about 125 nmol/L is raised. [25] A high level in someone taking no B6 points elsewhere, for example a low alkaline phosphatase (hypophosphatasia). [26]
Products at 10 mg or more should carry the 2026 warning; most Canadian licence records do not yet. Store at room temperature, dry.

What we know about Canadians

There is no national blood survey of B6 in Canada. In a 2016 sample of Vancouver women aged 19 to 35, 1.5% were deficient and 10.9% low; South Asian ethnicity, higher weight, low intake and taking no supplement predicted lower levels. [24] In Toronto, 3.6% of pregnant women in early pregnancy and 5.5% at delivery were deficient. [27]

Going over is the bigger issue. Nearly half of Canadians (45.6%) took a supplement in 2015, 68% of women over 70, and 23 to 25% a multivitamin. [28] How many Canadians take more than 10 mg of B6 a day has not been measured; in the US, supplement users were the ones who went over the B6 upper limit. [29] Over 4,000 licensed Canadian products give 10 mg a day or more, [2] including 79% of B-complex products. [22]

How sure are we: low. Deficiency figures come from small convenience samples (2016, 2018); no Canadian survey measures how many go over 10 mg; product counts come from a full licence scan (20 Oct 2026).

An honest comparison: nausea and vomiting in pregnancy

The only use of B6 with trials. Same 15-point nausea score; cost a month in Canadian dollars, estimated.

Option	Effect	How sure we are	Cost a month (CAD)
Pyridoxine (B6) alone	0.75 points better [9]	Low	$3 to $6
Small frequent meals, ginger	Not reviewed	Not reviewed	—
Doxylamine-pyridoxine (prescribed)	About 0.9 points more than placebo (4.8 against 3.9) [10]	Moderate	About $90 (4 tablets a day)

Read honestly: both effects are under one point on a 15-point score, and the prescribed product is the route, with the doctor or pharmacist who looks after the pregnancy. For energy, stress, mood or nerves there is nothing to compare: no benefit is shown without a deficiency.

Our verdict

We do not sell vitamin B6, and our check never adds a product with B6 if your total would reach 10 mg a day. Food gives you all you need. B6 your doctor prescribed (for nausea in pregnancy, with isoniazid, or a kidney vitamin) is counted in your total and never stopped by the check.

Already taking it? Add up the B6 in everything you take, including energy drinks. If it comes to 10 mg a day or more, stop the product with the most and keep at most one. If you have tingling, numbness or burning in your hands or feet, stop all of them and book a visit.

B6 has no proven benefit for anyone who is not short of it, apart from nausea in pregnancy, where a prescribed product exists. Against that, very high doses certainly damage the nerves, and Australia's reports, the Dutch data and Health Canada's 2026 review show harm can start well below the doses on most shelves. The certainty is low below 50 mg, but nothing is gained by taking the risk, and in Canada 79% of B-complex products give 10 mg a day or more, often without a warning on the licence. So our current advice is a 10 mg total from every source, which sits under Europe's 12 mg limit and at Canada's and Australia's warning line. Prescribed B6 is left alone, because Health Canada found no link with it and the medicines it goes with need it.