Do You Need a Prescription for B12 Injections? OmegaQuant The B12 Shot: What Every Human Needs to Know About Injectable Vitamin B12 Types of Injections, Same Needle Different Depths IV, IM, SC, and ID look similar but act very differently inside the body. This visual shows where each injection goes, how deep it travels, Syringes and Needles Medical Syringes Luer Lock B12 Shots Needle Size 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