from Hacker News

High vitamin B6 doses over a long period could cause irreversible nerve damage

by l8rlump on 5/30/25, 5:55 AM with 64 comments

• by pelorat on 5/30/25, 7:06 AM

  Happened to me too. I had been consuming two energy drinks per day for a week or so and then my SO (who's addicted to vitamin supplements) gave me some multivitamins that I took just to be nice. Apparently that pushed me over the edge.

  After one night and day of sweating profusely and feeling really bad, and me thinking I've cached a bug on my daily public commute, I didn't think about it any more, until days later when I began shedding the top layer of skin on my palms. Like, big flakes just started to fall off. Similar to what happens when you've had a severe sun burn.

  Once that was over, any my palms were back to normal, it was then I noticed that compared to previously, my sense of touch wasn't what it used to be. Also, I noticed that I wasn't sweating as much any more. It was at this point I went to see my GP who confirmed elevated levels of B6 but didn't give any other diagnosis. This was two weeks later though and I was still sporadically consuming energy drinks, but it made me remember reading about B6 toxicity, so I began looking into it.

  My own suspicion is that overconsumption of B6 damaged the nerve endings under my skin leading to a reduction in touch and the ability to sweat.

  So now I live my life with about a 25 to 50% reduction (subjective) of my sense of touch. Plus I barely sweat any more (which has it's upsides). Before, I was an "easy sweater" and would begin to sweat if I walked a kilometer to the train station in the summer (20C or so), but now I can be out all day in 30+ weather (~90F) without as much as a drop of sweat.

  I still sweat if I do actual prolonged physical exercise, like when I'm at the gym or exercise bike, but during daily life, not really any more. Also my hands are always dry and as a side effect quite slippery.

  So yeah, stay clear of vitamin supplements and overconsumption of energy drink. I'm just happy it wasn't worse in the end, as I've read about many life changing cases of B6 toxicity.

• by gloxkiqcza on 5/30/25, 6:35 AM

  The title mentions high doses and long periods, but let’s quantify it more accurately:

  Cases of toxicity have been reported at doses as low as 21 mg per day, the recommended daily intake is 1.3 to 2 mg. The person in question was diagnosed with issues possibly caused by this after 2 years.

  Edit: Clarification, the 21 mg figure isn’t from this article but from a related document released by Australian Therapeutic Goods Administration.

  https://consultations.tga.gov.au/medicines-regulation-divisi...

  Another news source: https://www.theguardian.com/australia-news/2025/jan/05/simon...

• by MassPikeMike on 5/30/25, 7:01 AM

  The article is quite one-sided. My experience is certainly that B6 has an effect on nerves, but in my case that's been a good thing.

  I started a software job in 1995, writing a lot of code. By mid-1997, I had severe nerve pain in both wrists, even with ice, stretching, and ibuprofen.

  I went to an excellent orthopedist who prescribed two things: a Kinesis Advantage keyboard to mostly immobilize the wrists while typing, and 50 mg of Vitamin B6 per day.

  The combination saved my career. I sometimes get out of the habit of taking the B6 for a week or two, out of sheer forgetfulness. After a couple of weeks, I'll start noticing very minor nerve pain if I'm using the Kinesis Advantage keyboard (I'm typing this on one right now.) But if I'm typing on a normal keyboard at a client site, a week or so is enough to bring back noticeable nerve pain, which reminds me to start the B6 regimen again. After a few days on B6, the pain recedes.

  I was a little nervous at taking 2500% of the RDA, so I researched the medical literature, and the studies I found showing problems caused by excessive B6 all described people taking 200mg or more per day.

  The article notes that "since 2022 the TGA has required a warning label for listed medicines with more than 10mg of B6." So maybe studies showing the potential for harm have come out since then; I don't know. On the other hand, has anyone ever gathered data to show whether supplemental B6 actually does improve cases like mine? Vitamin B6 can't be patented, so there's no money to be made, so who is going to fund that study?

• by viraptor on 5/30/25, 6:25 AM

  This is a tricky one with most cases I could find not actually documenting how much people were taking. With some cases mentioning people taking 500+mg, it's hard to tell how much causes problems. The original threshold was set by basically "we haven't seen issues with under 500mg, so set it to half that - 250mg it is".

  Btw, if you take more than 100mg, the serum level will easily go out of range for usual labs. (400+ nmol)

• by rapsey on 5/30/25, 7:06 AM

  I've had on and off insomnia for 20 years, mostly on and quite severe. If I exercised it got way worse, if I got sick sleep was practically impossible. B6 and magnesium have done absolute wonders for my well being.

  I also had problems with irritability. Especially if I got hurt in some way (like sprained wrist). If I get this way now, it is a clear sign I need to take B6. It fixes it right up.

  Both elements are something the body requires in the diet and does not store much. If you go to doctors most will tell you magnesium and b6 have nothing to do with sleep and give you melatonin, which is utterly useless to take regularly. It is very unfortunate how the medical profession is useless regarding fixing well being issues.

• by zingababba on 5/30/25, 7:34 PM

  Happened to me, took me three years to fully recover. After 2.5 years my blood test was FINALLY showing levels under the top of the range for B6 serum. At the worst I had full body muscle spasms that would go on 24/7, all the big and tiny muscles in my arms, face, legs. The worst however was I had esophageal spasms constantly which I confused for heart issues for the longest time. I completely lost feeling in my fingertips and toes. The list goes on.

  In all though I had pretty much every symptom listed here: https://understandingb6toxicity.com/b6-toxicity/symptoms/

  It's actually pretty crazy, I tested recently because I was curious and for the first time since I completely stopped B6 I took a 10mg dose and that evening my muscle spasms came back, my nervous system is so whacked out from this. This experience is what turned me off from supplements, it's horrible.

• by Elaris on 5/30/25, 8:00 AM

  It's kind of unbelievable that something that sounds so “harmless” like vitamins can actually pose serious risks when taken in high doses over a long period. The word “supplement” tends to give us a false sense of security, as if it must be safe by default. A lot of friends have told me that taking multivitamins is good for your health, but I’ve always been hesitant. I’ve felt that fresh fruit and a balanced diet are the more natural ways to nourish the body. Reading this article and the shared experiences here really surprised me. I had no idea vitamin B6 could affect different people in such dramatically different ways. Some seem to benefit, while others suffer from nerve issues. It makes me think maybe we’re too quick to assume more is better, and forget that what fits you is probably the most important thing.

• by antman on 5/30/25, 6:49 AM

  Looked it up on google and it provided me with this summary above the search:

  "Ultra Muscleze® P5P," a product by BioCeuticals, contains 53.7 mg of the active form of vitamin B6 (pyridoxal 5-phosphate monohydrate) per tablet. This equates to 34.2 mg of pyridoxine (vitamin B6).

• by drewbitt on 5/30/25, 6:04 PM

  I just looked at several B complexes and I don't see any above 20mg where it could be concerning. That's the only B vitamin, other than niacin, that I have ever taken or seen often recommended.

• by comrade1234 on 5/30/25, 7:41 AM

  Can you get your blood tested for vitamin, mineral, enzyme levels? You don't have to do it very often.

  I was borderline low on D and B12, but everything else was normal. So I take B12 and only take D in the winter. I would never take a general vitamin.

  There's some people on the internet that advocate taking massive doses of D. But the side effects (short term and long term) are just as nasty as having a deficiency.

  Anyway, get your blood tested and only take what's necessary.

• by Havoc on 5/30/25, 10:21 AM

  Just checked the supplement I've got around (solgar). 50mg with an asterisk that says long term use may lead to tingling and numbness.

  Holy hell...how is that even sold like that. That's going in the bin I guess

  Luckily I haven't been taking it regularly. Been leaning more & more towards taking a multi-vit every 2-3 days instead of daily.

• by Aziell on 5/30/25, 8:17 AM

  I actually take vitamin B6 every day and never thought it could have side effects. Reading this, I realized that taking too much for too long might damage your nerves , and it might not even be reversible. It's the kind of thing that's really easy to overlook.

• by cameldrv on 5/30/25, 3:12 PM

  B vitamin supplements are also linked to higher lung cancer rates, especially in male smokers.

• by 3eb7988a1663 on 5/30/25, 6:43 AM

  As someone taking magnesium, now I suddenly need to check my bottle.

• by gukov on 5/30/25, 7:31 AM

  Ugh, B6 a is part of the very popular ZMA...

• by looofooo0 on 5/30/25, 8:12 AM

  Why do people take multivitamin any how?