How to Give B12 Injections at Home to Yourself PA Relief How to Give a B12 Injection: Step By Step Instructions 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 How To Give a Subcutaneous (SubQ or SQ) Injection OncoLink How to Give a Subcutaneous Shot: Care Instructions B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics