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 B12 Injections at Allura Skin, Laser & Wellness Clinic Purchase Needles (PrecisionGlide) 1 inch or 1 2inch at BiosenseClinic like, swipe, and save for when it's your turn to do an injection on a patient Intramuscular (IM) Angle: 90 Needle Size: 2225G, 11.5 inch Med Examples: Vaccines (e.g. Tdap, Vitamin B12 10 Week Injection Cycle Kit: Syringes & Needles & Alcohol Wipes only 5.22