Oral vs. Intramuscular Vitamin B12 in Vitamin B12 Deficiency The Blood Project B12 Shots Dosage for Adults: How Much, How Often, and Key Injection Guidelines Liv Hospital Cyanocobalamin is the preferred supplemental form of vitamin B 12 as there is insufficient evidence to support the efficacy of the other forms like methylcobalamin. Michael Greger MD, How Not to Die. A Guide to Vitamin B Complex Injection Benefits and Dosage Cyanocobalamin (B12) Injection 1000 mcg mL, Multiple Dose Vial 30 mL McGuff How Vitamin B12 Injection Dosage and Frequency Influence Weight Loss AlabamaAgeline.gov