How to self inject intramuscular vitamin B12 Overview Guy's and St Thomas' NHS Foundation Trust Where Does B12 Injection Go TikTok 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 Needle Injection Techniques Every Nurse Should Know! Whether you're prepping for your NCLEX or brushing up on your skills, here's a quick breakdown of the most common injection routes you'll encounter Best Vitamin B12 Injection Sites? ThinWorks