Can you get too much vitamin B6?

The Tolerable Upper Intake Level for vitamin B6 is 100 mg a day for adults aged 19 and over.

What this means for you

Yes, and vitamin B6 is the reason the phrase "water-soluble vitamins are harmless" should be retired. The surplus does leave in urine. The nerve damage still happens.

Food is not the route. Chicken, fish, potatoes, chickpeas and bananas cannot take you near the 100 mg ceiling. Supplements can, and they are sold in exactly the sizes that do it, because 50 mg and 100 mg tablets are marketed for premenstrual symptoms, carpal tunnel and nerve complaints.

Not for everyone. Taking 1 to 6 grams a day for a year or more causes severe and progressive sensory neuropathy with unsteady walking. A review of the neuropathy literature set the caution much lower: more than 50 mg a day for an extended stretch may be harmful and should be discouraged. The first symptoms are numbness, tingling and clumsiness in the hands and feet, and they can take months to fade after stopping.

The cruel detail is that these are the same symptoms B6 deficiency causes, so someone taking B6 for tingling hands can make the tingling worse and read it as a sign they need more.

The pregnancy exception has a ceiling of its own

B6 is recommended for nausea in early pregnancy at doses a clinician sets, and that is the one place where taking it on purpose makes sense. It is also a place where people go past the limit by themselves.

Unsettled. Nineteen published reports describe women taking B6 above the upper limit for pregnancy sickness. Of 1,226 people in them, 164 had nerve symptoms: burning, tingling, pins and needles, unsteadiness, numbness around the mouth. Roughly one in seven. These are case reports with no comparison group, so that fraction describes the people who got written up rather than the odds facing anyone taking the tablets. It is also the only count anyone has.

Not for everyone. One signal comes from a randomised trial instead of from case reports. Among 352 women given doxylamine with pyridoxine for early pregnancy sickness, babies born small for gestational age were more common, an odds ratio of 3.8 with a confidence interval running from 1.0 to 14.1. The bottom of that interval sits at no effect and the top at fourteenfold. It was a secondary outcome, and it belongs to the combination rather than to B6 on its own. If you are on that prescription, raise it with whoever wrote it instead of stopping by yourself.

If you are taking B6 for a reason, check the actual number on the bottle rather than the picture on the front. A B-complex at 10 or 25 mg is a different product from a standalone 100 mg tablet taken daily for years.

Two groups are worth naming on the other side. People with reduced kidney function often run low, and valproic acid, carbamazepine and phenytoin speed up the breakdown of the vitamin. Both are reasons to have the conversation with a clinician rather than to self-prescribe in either direction.

One hundred milligrams is the American ceiling, and Europe has left it

Unsettled. The 100 mg figure on this page comes from the American authority. Europe no longer agrees with it. The EU committee said in 2000, and again in 2012, that harm below 100 mg a day was unlikely, then proposed 25 mg, and in 2023 EFSA cut the safe upper limit to 12 mg a day for adults, pregnancy and breastfeeding included. That is eight times lower than the number above. Nobody disputes the observations underneath. Adverse effects have been recorded above 50 mg a day taken for months to years, and clear nerve toxicity from 500 mg a day. What the two authorities disagree about is how much room to leave below the harm, and that disagreement is large enough to change what a normal tablet means.

Put concretely, if you are holding a 50 mg B6 tablet, one regulator calls that half the safe ceiling and the other calls it four times over it. The honest advice sits with the lower number, because nothing about B6 gives you a reason to want more of it.

The Netherlands acted before that review landed. From October 2018 supplements there were capped at 21 mg a day. The reports of nerve damage followed the cap down. After it, only one report involved a dose far above the new limit, a 2020 case taking 200 mg a day, and from the second half of 2019 the number of reports per period fell away.

Not for everyone. Two things in that same Dutch data deserve to be said out loud rather than tidied away. Reports of neuropathy at low doses kept arriving after the cap came in. And across the cases where both were recorded, the daily dose explained only 15 per cent of how much B6 ended up in someone's blood. So the number printed on the tablet is a weak guide to what is happening in any particular person. If your hands or feet start tingling or going numb while you are taking B6, a modest dose is not a reason to carry on. Stop it, and tell a doctor what you were taking.

The high-dose active form is not a safer version

Pyridoxal-5'-phosphate, sold as P5P, gets marketed as the form your body can use directly. There is one condition where that is exactly right. It is a rare inherited epilepsy called PNPO deficiency, treated from the newborn period, and it needs doses no shop sells.

Not for everyone. Among 49 patients treated that way, 10 developed raised liver enzymes, nine of them after more than a year on it, and two developed cirrhosis confirmed by biopsy. Both of those two needed 50 to 100 mg for every kilogram of body weight each day to keep seizures controlled, which for an adult would run into grams. One further patient was poisoned at 74 mg per kilogram because a food supplement label did not make clear what was in it. That last detail is the one to carry away from this section. The label was the problem.

Written from the evidence cards and the data on this page, then checked back against the sources. Bioma Learn has no human medical reviewer at this time and we say so rather than invent one. Information, not medical advice. How we verify.

Upper limits apply to everything you take in, from supplements and, for most nutrients, from food as well. Reaching one from whole food alone is uncommon. Supplements are where people cross the line, usually without meaning to.

Full guide: Vitamin B6: a water-soluble vitamin that can still damage nerves permanently