12 Week Steroid Injection Cycle Pack BD Needles, 2ml Syringes & Swabs Purchase Needles (PrecisionGlide) 1 inch or 1 2inch at BiosenseClinic 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 vitamin Store Needle and Syringe Information for injecting vitamin B12 and vitamin C. Find out what needle sizes are recommended. Dr. prescribed B12 injections. Pharmacy only gave me vials. Where do you get your needles and syringes? What size?? Where do I inject? : r B12_Deficiency