Does size matter? Historically, a bigger needle gauge was considered better to prevent damage to red blood cells. However, our recent guidelines recommend using smaller gauge needles (2325 G) for all Cyanocobalamin (Vitamin B12) Injection 1000 mcg mL, Multiple Dose Vial 1 mL, 25 Tray McGuff Vitamin B12 Injections Vitamin B 12 intramuscular injections are also used therapeutically to help restore energy and combat various symptoms related to such deficiencies. Vitamin B 12 is essential to the development of healthy blood cells, nerve