Skip to content

Coming soon. The store is not open yet.

Menu
Full Measure

Ingredient guide

Vitamin B6 side effects: when too much becomes a problem

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

Vitamin B6 from food has not been reported to cause harm. From supplements, large amounts taken for months or years can damage nerves, and can also cause painful skin patches, sensitivity to sunlight, nausea and heartburn. The US upper limit is 100 mg a day; Europe's, set in 2023, is 12 mg.1,2,3

Key facts

  • The best documented harm is to sensory nerves, at 1 to 6 g of pyridoxine a day taken for 12 to 40 months.1
  • The nerve effects usually stop when the supplement is stopped soon after they appear.1,2
  • Europe's 12 mg limit starts from 50 mg a day, a level linked to nerve effects in a case-control study, with a margin for uncertainty.3
  • The US limit does not apply to people taking B6 for medical reasons under a doctor's care.2

Nerve damage from too much B6

Taking 1 to 6 g of pyridoxine a day for 12 to 40 months can cause severe, progressive sensory neuropathy, with loss of control of body movements. The symptoms usually stop if the supplement is stopped as soon as they appear.1,2

Some reports describe sensory neuropathy at less than 500 mg a day, while studies of people taking about 200 mg a day for up to 5 years found none. The European panel took 50 mg a day, from a case-control study, as its reference point for nerve harm.1,3

If you notice changes in sensation or balance while taking vitamin B6, stop it and see a doctor, and bring the labels of everything you take.

Other effects of too much

Other effects of too much vitamin B6 include painful, disfiguring skin patches, sensitivity to sunlight, nausea and heartburn.1,2

Why the two limits differ

The US upper limit for vitamin B6 is 100 mg a day for adults, counting food and supplements together. It is 80 mg for ages 14 to 18, 60 mg at 9 to 13, 40 mg at 4 to 8 and 30 mg at 1 to 3. In 2023 the European Food Safety Authority set a lower adult limit of 12 mg a day, including during pregnancy and breastfeeding. The US limit does not apply to people taking B6 for medical reasons under a doctor's care.1,2,3

The US board noted reports of nerve damage below 500 mg a day but found none in studies of people taking about 200 mg a day for up to 5 years, and halved that figure to reach 100 mg. The European panel started from 50 mg a day, the level a case-control study pointed to, and divided it by 4 for uncertainty, which gave 12.5 mg; together with an animal study, that led to 12 mg.1,3

EFSA expects only regular users of high-dose supplements to go over its limit.3

In pregnancy

Isolated case reports describe birth defects in babies whose mothers took pyridoxine supplements in the first half of pregnancy. A later observational study of women who took an average of 132 mg a day from week 7 of pregnancy found no link.1

NIH advises pregnant women to consult a doctor before taking a vitamin B6 supplement, because the amounts used could approach the upper limit.1

Medicines that interact

Some medicines and vitamin B6 affect each other. NIH and the carbidopa and levodopa label describe effects with levodopa, anti-seizure medicines such as phenytoin, the antibiotic cycloserine and theophylline. If you take one of these, ask your doctor before taking B6.2,4

What's in ours

What’s in ours

If you take more than one of these, add up the vitamin B6 on the labels.

Questions people ask

Is vitamin B6 safe in the first trimester?

Ask your doctor before taking more than a prenatal vitamin provides. Isolated case reports raised concerns about pyridoxine early in pregnancy, but a later observational study at an average of 132 mg a day found no link with birth defects. NIH notes that amounts used in pregnancy under medical care can approach the upper limit.1

How much vitamin B6 is too much?

In the US, more than 100 mg a day for adults from all sources; in Europe, more than 12 mg. Nerve damage is best documented at 1 to 6 g a day over a year or more, but has been reported below 500 mg a day.1,3

Is it safe to take vitamin B6 every day?

Food supplies vitamin B6 every day, and the upper limits are daily amounts considered unlikely to cause harm over the long term: 100 mg in the US and 12 mg in Europe. The trouble comes from high doses taken daily for months or years.1,3

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure lineAshwagandha ComplexImmune SupportMen's Multi

Sources

  1. National Institutes of Health, Office of Dietary Supplements. Vitamin B6: Fact Sheet for Health Professionals. Updated June 16, 2023. Opened 2026-10-07.
  2. National Institutes of Health, Office of Dietary Supplements. Vitamin B6: Fact Sheet for Consumers. Updated June 16, 2023. Opened 2026-10-07.
  3. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Scientific opinion on the tolerable upper intake level for vitamin B6. EFSA J. 2023;21(5):e08006. Opened 2026-10-07.
  4. Carbidopa and levodopa tablets: prescribing information (Advagen Pharma). DailyMed, U.S. National Library of Medicine. Published September 28, 2026. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.