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 Know Your Needles A Quick Nursing Guide! Today, let's understand the different types of needles and their clinical purposes Green Needle (21G) For IM injections like Needle Sizes Explained: Choosing the Right Gauge for Different Injections For subcutaneous injections, using shorter needles (4 5mm) is the safest choice to ensure medication stays in the fatty layer and avoids muscle injury. A 4mm needle is ideal, minimizing pain while keeping B12 Injection Needle Size B12 Syringes Is b12 im or sq