B12 Injections East Valley Urology Center of Arizona Oral vs. Intramuscular Vitamin B12 in Vitamin B12 Deficiency The Blood Project Vitamin B12 Injection Dose for Weight Loss: What Does the Science Say? AlabamaAgeline.gov Cyanocobalamin (B12) Injection 1000 mcg mL, Multiple Dose Vial 30 mL McGuff 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.