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 Vitamin b12 infographic needle injection syringe medical Premium Vector VanishPoint 29 Gauge x 5 16 inch Retractable Insulin Syringe with Needle 1 mL, Regular Wall, 100 Box Is this the right size needle for im injections? : r B12_Deficiency