Vitamin B6
Vitamin B6 is the B vitamin with the clearest harm from taking too much. Months to years above the intake limit can damage the nerves in the hands and feet, and recovery is not guaranteed. Many "energy" and "stress" B-complex formulas contain far more than the European limit.
Keep your total vitamin B6, from food and supplements together, under 12 mg a day. Check the label of any B-complex, and stop it at once if you notice tingling or numbness in your hands or feet.
What it is
Vitamin B6 is one of the eight B vitamins: small molecules that enzymes need to run the body's chemistry. Together with folate and vitamin B12, it is one of the cofactors that clear homocysteine, an amino acid that builds up when B-vitamin status is poor. It is sold as pyridoxine or as pyridoxal-5-phosphate (P5P), the active form. A healthy adult eating animal products and a reasonable variety of plants gets plenty from food.
More is not safer: the nerve damage
Taking more than the intake limit for months to years can cause a sensory peripheral neuropathy: damage to the nerves that carry sensation, felt as tingling and numbness in the hands and feet. Symptoms usually stop if the supplement is stopped as soon as they appear.[1]
Recovery is not guaranteed, though. In Australia's 2025 review of vitamin B6, 103 people reported severe and sometimes permanent effects, including nerve damage and muscle weakness. Australia's medicines regulator, the Therapeutic Goods Administration, concluded that neuropathy can occur at 50 mg a day or even lower.[2]
Taking the active form does not change this. P5P is sometimes preferred, but the same dose caution applies.
Which limit to use
The limits differ by country, so use the most cautious one.
- Europe: 12 mg a day. The European Food Safety Authority (EFSA) sets the tolerable upper limit for adults at 12 mg a day, counting food and supplements together. That is far below the doses in many B-complex products.[3]
- Australia: 50 mg a day, and under review. Australia has required a nerve-damage warning on products with more than 10 mg a day since 2022.[4] From 1 June 2027, products with more than 50 mg per daily dose will need a pharmacist's advice to buy; above 200 mg they already need a prescription. Australia's own 50 mg limit is itself under review, due by early 2027.[5]
Two weaker signals: lung cancer and hip fracture
Two large observational studies add reasons to be wary of high-dose B6. Both are associations, open to confounding, and not proof of harm.
- Lung cancer, in men. In a cohort of 77,118 people, long-term use of individual B6 supplements at more than 20 mg a day was tied to about 1.8 times the lung-cancer risk in men. The result was strongest in current smokers. There was no link in women, and none from multivitamins.[6] High-dose B12 showed a similar signal in the same study.
- Hip fracture. In 75,864 women in the Nurses' Health Study, a combined high intake of B6 and B12 was linked to more hip fractures. B12 alone carried no such signal.[7]
What to do
- Add up the B6 in everything you take — B-complex, multivitamin, "energy" or "stress" formulas — and keep the total under 12 mg a day.
- Skip stand-alone high-dose B6 products.
- Stop at the first tingling or numbness in your hands or feet, and tell your doctor.
- Don't treat P5P as a safer form. The same limit applies.
Further reading
- Brasky TM, White E, Chen CL. Long-Term, Supplemental, One-Carbon Metabolism-Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort. J Clin Oncol 2017.[8]
- Meyer HE et al. Association of High Intakes of Vitamins B6 and B12 From Food and Supplements With Risk of Hip Fracture Among Postmenopausal Women in the Nurses' Health Study. JAMA Netw Open 2019.[9]
- EFSA. Overview on Tolerable Upper Intake Levels. EFSA, version 11, August 2025.[10]
- Therapeutic Goods Administration. Notice of final decision to amend (or not amend) the current Poisons Standard in relation to pyridoxine, pyridoxal or pyridoxamine (vitamin B6). 2025.[11]