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 B 12 (Methylcobalamin) Therapy MedClub by Dr Jenn How to Give B12 Injections at Home to Yourself PA Relief Places for Intramuscular Injection: 4 Safe Spots B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics