Cyanocobalamin (B12) Injection

(Commercial Product)

Available Dosage Strengths

1,000 mcg/mL

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Product Overview

Description

Cyanocobalamin, synthetic compound of vitamin B12, supports several methylation reactions in the body. It is essential for growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. Cells characterized by rapid division (epithelial cells, bone marrow, myeloid cells) appear to have the greatest requirement for cyanocobalamin.¹

Cyanocobalamin has many approved indications (many that lead to a deficiency of cyanocobalamin through an impairment of absorption of cyanocobalamin) including:

Pernicious anemia
Malabsorption
Atrophic gastritis
Long-term metformin use
Chronic acid-reducing medication use
Small bowel bacteria overgrowth
Total or partial gastrectomy
Diphyllobothrium latum infection
Helicobacter pylori infection
Pancreatic insufficiency
Malignancy of the pancreas or bowel
Dietary deficiency of vitamin B12
Transcobalamin II deficiency

Cyanocobalamin can be administered via intramuscular (IM) or subcutaneous (SC) routes.

Mechanism of Action

Vitamin B12 is important for division and growth of the cell. It is converted to coenzyme B12 in the body and in this form facilitates the conversion of homocysteine to methionine (methylcobalamin) and plays an important role in converting methylmalonyl-coenzyme A to succinyl-Co-A (fatty acid and amino acid metabolism). Without coenzyme B12, tetrahydrofolate cannot be produced from 5-methyl tetrahydrofolate leading to folate deficiency. In addition, vitamin B12 is needed to produce myelin and is important for axon and nerve development. Gastrointestinal absorption of vitamin B12 depends on the presence of sufficient intrinsic factor and calcium ions.^1-3

Adverse Reactions

Common:^1-3

Pruritus, transitory rash and a feeling of swelling (edema) of the entire body
Pain or redness at injection site
Headache

Contraindications & Precautions

Contraindications:^1-3

Hypersensitivity or intolerance to cyanocobalamin or cobalt or its excipients
Aluminum; toxic aluminum concentrations may be seen with high doses, prolonged use, or renal dysfunction

Precautions:^1-3

Monitor for hypokalemia, after initial treatment, an increased red blood cell production may occur which may lower serum potassium levels
Use with caution in individuals with polycythemia vera or renal disease .

Storage

Store at 20°C to 25°C (68°F to 77°F). Do not freeze. Protect from light and moisture. Keep in original packaging and out of reach of children [13].

References

Vasavada A, Patel P, Sanghavi DK. Cyanocobalamin. StatPearls. January 31. 2024. Accessed August 10, 2025. https://www.ncbi.nlm.nih.gov/books/NBK555964/
Clinical Pharmacology Cyanocobalamin clinical monograph 2025 https://www.clinicalkey.com/pharmacology/ 
Cyanocobalamin package insert. American Reagent January 2021. https://www.americanregent.com/media/3187/cyanocobalamin-insert-in0031-rev-1-2021.pdf Accessed August 10, 2025.

Disclaimer

This sheet is a summary. It may not cover all possible drug information about this product. Call your doctor for medical advice and/or about side effects. You may report side effects to the FDA at 1-800-FDA-1088. A Wells Pharmacy Network pharmacist will be happy to answer any questions. For consultation, please call 1-800-622-4510.