What needle size is best for injec Pernicious Anaemi Treating Severe Vitamin B12 Deficiency B12 IM Injection What is the recommended needle size and gauge for intramuscular (IM) injections? Needle and Syringe Combos 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, 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