Reviewed on 8/26/2021

What Is Cyanocobalamin and How Does It Work?

Cyanocobalamin is a prescription and over-the-counter (OTC) man-made form of vitamin B12 used to prevent and treat low blood levels of vitamin B12. Most people get enough vitamin B12 from their diet. Vitamin B12 is important to maintain the health of your metabolism, blood cells and nerves. Serious vitamin B12 deficiency may result in a low number of red blood cells (anemia), stomach/intestine problems, and permanent nerve damage.

  • Vitamin B12 deficiency may occur in certain health conditions, such as intestinal/stomach problems, poor nutrition, cancer, HIV infection, pregnancy, old age, alcoholism. It may also occur in people who follow a strict vegetarian (vegan) diet.
  • Cyanocobalamin is available under the following different brand names: Vitamin B12, Nascobal, Athlete, Calomist, Cobalamin, Cobex, Crystamine, Prime, Rubramine PC, Vibisone, and Eligen B12.

What Are Dosages of Cyanocobalamin?

Dosages of Cyanocobalamin:

Adult and pediatric dosages:


  • 100 mcg
  • 250 mcg
  • 500 mcg
  • 1,000 mcg

Tablet, extended-release

  • 1,000 mcg

Tablet, sublingual

  • 2,500 mcg

Injectable solution

  • 1,000 mcg/ml

Nasal spray

  • 500 mcg/spray

Dosage Considerations – Should be Given as Follows:

Nutritional Supplementation


  • Adults over 19 years: 2.4 mcg
  • Pregnant women: 2.6 mcg
  • Breastfeeding women: 2.8 mcg
  • Dietary supplement: 50-6,000 mcg/day


  • Infants 0-6 months: 0.4 mcg
  • Infants 7-12 months: 0.5 mcg
  • Children 1-3 years: 0.9 mcg
  • Children 4-8 years: 1.2 mcg
  • Children 9-13 years: 1.8 mcg
  • Children over 14 years: 2.4 mcg

Pernicious Anemia

Adult Dosages

  • Manufacturer recommendation: 100 mcg intramuscularly or subcutaneously once daily for 6-7 days, then every other day for 7 doses, then 3-4 days for 2-3 weeks, then monthly
  • Alternative parenteral dosing: 1,000 mcg intramuscularly or subcutaneously once daily for 7 days, then weekly for 1 month, then monthly
  • Nasal spray: 500 mcg (1 spray in 1 nostril) weekly; if the patient is taking hot meals, the spray should be administered 1 hour before or after a meal

Pediatric Dosages

  • 30-50 mcg intramuscularly or subcutaneously once daily for 2 weeks or more for a total dose of 1,000 mcg to 5,000 mcg administer concomitantly with 1 mg/day of folic acid for 1 month
  • Maintenance: 100 mcg intramuscularly or subcutaneously monthly

B12 Deficiency

Adult Dosages

  • Initial: 30 mcg intramuscularly once daily for 5-10 days
  • Maintenance: 100-200 mcg intramuscularly monthly
  • Nasal dose: 500 mcg once weekly

Dosing considerations:

Pediatric Dosages

  • 0.2 mcg/kg for 2 days; follow by 1,000 mcg/day for 2-7 days; follow by 100 mcg/day for 2-7 days; then 100 mcg/week for 1 month


Next to red peppers, you can get the most vitamin C from ________________. See Answer

What Are Side Effects Associated with Using Cyanocobalamin?

Side effects of cyanocobalamin include:

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Cyanocobalamin?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Cyanocobalamin has no known severe interactions with other drugs.
  • Cyanocobalamin has no known serious interactions with other drugs.
  • Moderate interactions of cyanocobalamin include:
    • Dichlorphenamide
  • Cyanocobalamin has minor interactions with at least 71 different drugs.

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more information about this medicine.

What Are Warnings and Precautions for Cyanocobalamin?


  • This medication contains cyanocobalamin. Do not take Vitamin B12, Nascobal, Athlete, Calomist, Cobalamin, Cobex, Crystamine, Prime, Rubramine PC, Vibisone, or Eligen B12 if you are allergic to cyanocobalamin or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


  • Hypersensitivity to the product; sensitivity to cobalt
  • Effects of Drug Abuse
  • No information available

Short-Term Effects

  • See "What Are Side Effects Associated with Using Cyanocobalamin?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Cyanocobalamin?"


  • Intensive treatment of B12-deficient megaloblastic anemia may cause hypokalemia and sudden death
  • Nasal disease; defer use until symptoms resolve
  • Use with caution in patients with Leber optic nerve atrophy
  • The injection is incompatible with some common drugs (warfarin and several phenothiazines) but is compatible with vitamins B and C
  • Vitamin B12 deficiency for over 3 months results in irreversible degenerative central nervous system lesions
  • Thrombocytosis (too many platelets) may occur with the treatment of severe vitamin B12 megaloblastic anemia
  • Oral and intranasal routes are not indicated for the treatment of pernicious anemia until systems resolve

Pregnancy and Lactation

  • Cyanocobalamin is generally acceptable for use during pregnancy
  • Controlled studies in pregnant women show no evidence of fetal risk
  • For cyanocobalamin doses exceeding the recommended daily average, and for intranasal products during pregnancy, use with caution during pregnancy if benefits outweigh risks
  • Animal studies show risk and human studies are not available, or neither animal nor human studies were done
  • Cyanocobalamin is distributed in breast milk; it is safe to use while breastfeeding


Vitamin D Deficiency: How Much Vitamin D Is Enough? See Slideshow
Medscape. Cyanocobalamin.
RxList. Cyanocobalamin Side Effects Center.

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