oral cyanocobalamin (Vitamin B-12)

Medically Reviewed on 10/28/2022

Generic Name: cyanocobalamin 

Other Names: Vitamin B12, B12

Drug Class: Vitamins, Water-Soluble

What is cyanocobalamin, and what is it used for?

Cyanocobalamin or vitamin B12 is an essential B-vitamin that is classified as a water-soluble vitamin. Food sources of vitamin B12 include fish, shellfish, meats, and dairy products.

Vitamin B12 is necessary for growth, reproduction of cells (for example, production of red blood cells, and the production of myelin that protects nerves and proteins within the nucleus of cells. Vitamin B12 also plays an important role in the breakdown or metabolism of fats and carbohydrates and production of proteins. Vitamin B12 deficiency may result in anemia, gastrointestinal problems, and nerve damage.

What are the side effects of cyanocobalamin tablets?

Common side effects of cyanocobalamin include:

Other possible side effects of cyanocobalamin include:

What is the dosage for cyanocobalamin?

  • The recommended dose for treating vitamin B12 deficiency is 1000 mcg daily.
  • The recommended dose for preventing vitamin B12 deficiency is 1500 mg or 2500 mcg (sublingual tablets) daily.
  • The dose for treating hyperhomocysteinemia is 400 mg daily in combination with folic acid.

What drugs interact with cyanocobalamin?

  • Chloramphenicol may decrease the effectiveness of cyanocobalamin.
  • Cancer drugs may reduce the response to cyanocobalamin treatment.
  • Use of colchicine and heavy alcohol intake for longer than 2 weeks may decrease the absorption of vitamin B12.

Are cyanocobalamin safe to take if I'm pregnant or breastfeeding?

  • Cyanocobalamin has not been adequately evaluated in pregnant women. However, vitamin B12 is an essential vitamin and requirements are increased during pregnancy.
  • Cyanocobalamin is excreted into human milk and is safe to use while nursing. Vitamin B12 requirements are increased in nursing mothers.

What else should I know about cyanocobalamin?

Do I need a prescription for cyanocobalamin tablets (Vitamin B-12)?

  • No, they are available over the counter.

What preparations of cyanocobalamin tablets are available?

  • Tablets: 100, 250, 500, and 1000 mcg
  • Tablet (extended release): 1000 mcg; Tablet (sublingual): 2500 mcg
  • Capsules: 250 and 500 mg

How should I keep cyanocobalamin tablets stored?

  • Tablets should be stored at room temperature, 20 C to 25 C (68 F to 77 F).


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Oral cyanocobalamin (Vitamin B12) is prescribed to prevent or treat vitamin B12 deficiency and to treat hyperhomocysteinemia. Side effects, drug interactions, dosing, storage, and pregnancy and breastfeeding information should be reviewed prior to taking this product.

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Medically Reviewed on 10/28/2022
Medically reviewed by John P. Cunha, DO, FACOEP; Board Certified Emergency Medicine


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