Common IM Injection Sites Deltoid (Upper Arm) Location: About 23 finger widths below the acromion process (shoulder bone). Best for: Vaccines and small volume injections (1 mL). Notes: Easy to access but limited Best Vitamin B12 Injection Site: Administering B12 Shots Choosing the Right Needle and Syringe for B12 Injections: A Complete Guide 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 Administration of vaccines The Australian Immunisation Handbook B12 vitamin Store How to Perform a Subcutaneous Injection of Vitamin B12