How your B12 injection is given and what it does for your body In this reel, I talk through the wonderful benefits of B12 for energy, focus, and overall How to self administer subcutaneous B12 injection. 1. Withdraw proper dosage from vial into an insulin syringe 2. Clean site of injection (abdomen or other proper site) 3. Pinch the skin where Best Vitamin B12 Injection Sites: Where to Inject B12 PA Relief B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics