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Vitamin B6 Toxicity -- Vitamin B6 Blood Test


As noted in our B Vitamin Supplements Review, unless you are deficient, you only need to get slightly less than 2 mg of vitamin B6 per day from your diet (including supplements), while the daily upper tolerable intake level (UL) is 100 mg. [The Daily Value for B-6 was reduced in 2016 from 6 mg to 1.7 mg, but this change won't be reflected on most supplement labels until 2021.] When you exceed the UL, you start increasing your chances of side effects.

Since supplements are required to provide at least 100% of their listed amounts of ingredients at the time you purchase them and, if properly maintained, until a listed expiration date, it is customary and acceptable for companies to put in a bit more (an "overage") than the listed amount of an ingredient to compensate for normal degradation. In fact, according the USP, up to 50% more is permitted for B vitamins.

So, yes, it is possible that your multivitamin provided more than the daily upper limit of vitamin B6 -- putting you at some risk of toxicity with long-term use. This is because your supplement provided an amount of B6 close to the upper limit (and much more than normally needed) and there is an allowable manufacturing overage, as noted above. However, side effects have generally been reported with daily intakes above 200 mg and, more typically, above 1,000 mg, so, although possible, it would be unusual for the B6 in your supplement alone (if properly made) to cause the side effects you reported. Foods also contribute B6, but non-fortified foods would be unlikely to put you over the UL since foods naturally rich in B6 (like liver, other meats, potatoes, and bananas) provide about only about 0.25 to 1 mg of B6 per serving. Be aware that energy drinks may include large amounts of vitamin B6 and have been implicated in cases of vitamin B6 toxicity.

Be aware that Europe uses a more conservative daily upper limit (25 mg) than in the U.S., so even your "75 mg" B6 supplement would exceed the limit in Europe.  

Unless you have been diagnosed with a deficiency in vitamin B6, there is no good reason to take more than 2 mg of B6 per day and certainly no more than 25 mg.

For more about vitamin B6 see the B Vitamin Supplements Review >>

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April 2, 2020

My understanding is that neurological damage does not manifest until high doses of B-6 have been taken for 3 or more years - one of the reasons it has not typically been associated with such damage until fairly recently.
April 2, 2020

Yes, neurological symptoms from too much vitamin B6 may take over a year to develop.

June 19, 2019

I am experiencing very painful neuropathy in my feet and have been taking a multi with 50 mg of B6. My blood test came back extremely high in that vitamin and I was advised to stop it.
So far the pain is better after 4 months and I hope it continues to improve.

It's now been over 6 months and the neuropathy is gone. I will not be taking B6 again.
I have the MTHER Gene according to 23andMe which can makes me absorb toxic levels of the vitamin.

November 4, 2018

About 30 years ago, I experienced painful tingling and numbness in my feet and tingling in my spine when I bent my head. I went to many neurologists and a major neurological hospital in New York City, but despite painful tests no one diagnosed the problem. The internet did not exist but one day I read an article in a health magazine which described my symptoms and attributed them to Vitamin B-6 overload. The article even labelled my spine issue Lhermitte's Syndrome, named for a doctor. I had been taking too much B-6 due to the advice of a popular health author of the 80's. I immediately stopped B-6 and months later the symptoms disappeared except for a permanent minor residual numbness and pain in the toes of one foot.

March 29, 2017

I suffered from a large B6 deficiency. It caused symptoms from temperature regulation to mental function. Something circulating in the blood was compounding it to take it out. Cure was to take 50 to 100 mg/day. Really made a big difference. It seems we don't know much about this vitamin if some people are reporting toxic effects at these levels.
April 7, 2017

Hi Arch - Higher doses may be appropriate to correct a deficiency, but if you are not deficient and get too much B-6, adverse effects can occur.

April 9, 2017

I think the EU, Great Britain and Canada are way ahead of the US, in considering safety issues. I had been taking 100mg of B6 daily, and now take only 25mg. I changed several months ago, when a saw an article on this issue.
April 10, 2017

That's good. Just for others who may be reading this, keep in mind that this is an upper limit. If you are not deficient, it's still way above the amount most people need.

July 5, 2015

Re companies putting in on overage of an ingredient to maintain 100% of the required amount over time: Hard to imagine they feel the need to do this when the expiration date is typically 2 or 3 years after manufacture, similar to what drugs makers list as the shelf life in the original bottle a pharmacist receives. While I know it's not recommended -- and may vary by drug -- I have taken ibuprofen, as well as several blood pressure medicines, more than 5 years past the expiration date, and they were just as effective as they were originally. It would be interesting for CL to test some passing supplements that expired years ago, and see what kinds of results you get re degradation (or not).

July 5, 2015

I just noticed this article in the new issue of J of Nutrition. The genetic stuff is technically a bit over my head but it may be relevant to this discussion if anyone wants to take a look -

"Common Variants at Putative Regulatory Sites of the Tissue Nonspecific Alkaline Phosphatase Gene Influence Circulating Pyridoxal 5'-Phosphate Concentration in Healthy Adults" J. Nutr. July 1, 2015vol. 145 no. 7 1386-1393

(Pyridoxal 5'-Phosphate is the biomarker of B6 as measured in plasma)

July 2, 2015

I know another patient who had a very similar experience. She was taking a standard B supplement with 100% the daily value of B6, and no other supplements or other products containing B vitamins. She rapidly developed neurological symptoms, which resolved when she switched to taking B1 and B2 supplements without any B6. I would love to gather more reports of this response -- I suspect that there may be some people who are hypersensitive to B6, or who have a variation in B6 metabolism that allows them to reach toxic levels at "normal" supplement doses.
July 2, 2015

Hi Michael - Please note that it would be very unusual to develop B-6 toxicity from a supplement claiming 100% of the Daily Value (which is 2 mg), unless there was a significant manufacturing error.

July 2, 2015

I agree that this would be unusual; the question is whether it's impossible (barring a manufacturing error, as you noted), or whether there's a small subset of people who are hypersensitive to B6 supplementation. If such people do exist, it would be important for doctors and consumers to know that they shouldn't categorically rule out normal levels of B6 supplementation as a possible cause of neurological symptoms.

July 1, 2015

I had a similar experience. My B-Complex only had 50mg of B6, but when my PCP tested by B6 levels, they were 5x what they should have been. He told me to immediately stop my supplement - permanent damage can occur if the B6 levels are too high for too long. I stopped the supplement and my symptoms resolved over time.

July 2, 2015

If you wouldn't mind sharing, what were the side effects you were experiencing?
July 2, 2015

Hi Catherine - The side effects the CL Member reported experiencing were neurological symptoms, tingling & buzzing of feet, skin crawling sensations, balance problems, dizziness, brain fog, fatigue, skin allergies and acne.

July 1, 2015

Are you drinking energy drinks? They're full of B-Vitamins. Like 1200% of daily requirement.

Enid Marie5826
July 1, 2015

I thought the B vitamins were all water soluble and did not build up in the body so you would not build up toxic levels,
July 7, 2015

Hi Enid - Thank you for your question. We've now answered it here:

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