P1

itamin B12 is found in seafood, dairy, and eggs. The body uses B12 to keep nerve cells and blood cells healthy. Vitamin B12 has been used for pregnancy support and to improve mental well-being. It has also been used to improve bone, lung, and heart health. It is used to manage vitamin B12 deficiency. Vitamin B12 can be taken as a pill, powder, or tincture. It can also be injected into the bloodstream or muscle by a healthcare provider.

Dosages

2.4 micrograms for adults

3000 to 5000 micrograms daily for vitamin B12 deficiency

P5

Likely effective

May be effective

  • Shingles—likely to improve quality of life in those with postherpetic neuralgia F1

Unlikely to be effective

Not enough data to assess

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

P6

It is likely safe to take vitamin B12 in small doses for a short time. Not enough studies have been done to say whether it is safe to take for a long period.

Weakness, skin tingling, and headache may happen in some people. Women who are pregnant or breastfeeding should not take large doses of vitamin B12.

Interactions

Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse, such as:

  • People taking nasal medicines or bone marrow suppressants should talk to their doctors before taking this vitamin.
  • People with infection, iron deficiency, Leber disease, megaloblastic anemia, renal impairment, or blood in their urine should talk to their doctors before taking this vitamin.
  • Talk to your child’s doctor before giving this vitamin to a premature infant.