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A Hidden Risk: Could Excess Vitamin B6 Damage Nerves?

When vitamins hurt: The link between excess vitamin B6 and nerve damage. How much pyridoxine is safe and how much could lead to neuropathy?

Whether you utilize pharmaceutical medicines or look to natural remedies such as vitamins and minerals, you must make sure the treatment is not worse than the ailment. People who consult health care providers about medication side effects might assume that dietary supplements are completely safe. That is a significant danger if someone takes excess vitamin B6 to try to boost immunity, improve mood or treat neuropathy or carpal tunnel syndrome.

Vitamin B6 (Pyridoxine):

Why Overdosing Can Lead to Painful Nerve Damage:

Q. For some time, I’ve had weird tingling feelings in my feet that have been diagnosed as idiopathic peripheral neuropathy. I’m not diabetic, and nobody seems to know why I got this or what to do about it. All the neurologists I saw gave a big shrug.

A blood test showed that my level of B6 was ten times higher than normal, but nobody seemed to think that was relevant. Then a doctor friend of mine sent an article about vitamin B6 causing peripheral neuropathy. The usual source is supplementation. After that, I found corroborating evidence (not anecdotes).

I know a lot of people who have developed this condition. They should take a look at the supplements they are taking to see if they are getting too much vitamin B6–and then stop taking it! It seems the bad effects may be reversible.

A. Scientists have known for more than 20 years that excess vitamin B6 from supplements could harm the nervous system. This was associated with prolonged intake of doses of 50 mg/day or more. The Food and Nutrition Board has established a tolerable upper limit of 100 mg vitamin B6 for adults.

More recently, nutrition experts have found that vitamin B6 supplements at much lower levels can cause neuropathy (Drug Safety, Sep. 2018). However, the vitamin dose isn’t always linked to the blood levels of the patients. Even a multivitamin may be too much for some people (Journal of Nutrition, Health & Aging, Jul-Aug. 2007).

We hope that you have stopped your supplement and will soon find your neuropathy lessening. Foods such as chickpeas, tuna, salmon and chicken breast appear to be safe ways to get the vitamin B6 you need.

Easing Carpal Tunnel Syndrome:

Q. I believe my friend has carpal tunnel syndrome from doing repetitive work at his job. Is there anything he can take for it that’s a natural anti-inflammatory?

A. Carpal tunnel syndrome occurs when the median nerve in the wrist is pinched, often from repetitive motions. Symptoms can include numbness, tingling, burning and weakness in the hand or arm.

Doctors often recommend anti-inflammatory drugs like ibuprofen. Acupuncture was shown in one small study to be as good or better than ibuprofen for relieving pain, numbness and tingling at night (Hadianfard et al, Journal of Acupuncture and Meridian Studies, Oct. 2015). A review concludes that acupuncture “may be beneficial for CTS” [carpal tunnel syndrome] (Cox et al, Journal of Orthopaedic and Sports Physical Therapy, June 2016).

Physical Therapy for Carpal Tunnel Syndrome:

When doctors want to treat this painful problem without surgery, they often recommend a brace or splint. A recent study found that people who did hand exercises squeezing a foam ball with rubber cords attached had slight improvement in their symptoms (Unver & Akyolcu, Asian Journal of Neurosurgery, Jan-Mar. 2018). A physical therapist would be able to instruct your friend on the best exercises for this problem.

Does Vitamin B6 Help Carpal Tunnel Syndrome?

Vitamin B6 (pyridoxine) has been a controversial treatment for carpal tunnel syndrome. Some clinicians maintain it is ineffective (Wipperman & Goerl, American Family Physician, Dec.15, 2016). Others say it works to ease symptoms (Talebi et al, Advanced Pharmaceutical Bulletin, online Aug. 20, 2013).

Beware Excess Vitamin B6:

We offer a word of caution about this nutrient, though. Large doses or prolonged treatment can cause nerve damage, as this reader discovered:

“I found out 30 years ago that taking Vitamin B6 helped me get rid of carpal tunnel syndrome. However, I made the mistake of continuing to take it for decades.

“I eventually developed B6 toxicity. By then it was having the opposite effect of making my hands AND feet numb. It took me a long time to figure out what was going wrong, since my doctor insisted there was no such thing as B6 toxicity. By trial and error I found that stopping the B6 made the numbness go away.”

Doctors have written about numerous cases of excess vitamin B6 causing nerve damage (Bacharach, Lowden & Ahmed, Journal of Clinical Neuromuscular Disease, Sep. 2017; Scott, Zeris & Kothari, Electromyography and Clinical Neurophysiology, Jun-Jul. 2008).

Usually any damage to the nerves caused by excess vitamin B6 is reversible once the vitamin is stopped. That is not always the case, however (Kulkantrakorn, Neurological Sciences, Nov. 2014). According to the Office of Dietary Supplements, adults should not take more than 100 mg a day. The recommended daily allowance is much less–1.3 mg per day for adults up to age 50 and a little bit higher than that for people over 51.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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