5+ Ultimate Tips On How To Give B12 Shot You Must Follow How Quickly Do Vitamin B12 Injections Work? Prime Aesthetics Ivy Grove Surgery : Self administration of B12 injection Subcutaneous (SC) and Intramuscular (IM) Injections Must Knows for Subcutaneous administration: Pinch skin with non dominant hand and hold syringe with dominant hand Always inject: 2 inches away from umbilicus (for abdomen) 3 inches Intramuscular Injection (IM) OSCE Guide IM Injection Geeky Medics 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