How to Give a B12 Injection: Step By Step Instructions VITAMIN B12 INJECTION Not all shots are the same here's a guide Injections are a fast, effective way to deliver medications, nutrients, and vaccines directly into the bodybut not all injections are the B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics Dr. prescribed B12 injections. Pharmacy only gave me vials. Where do you get your needles and syringes? What size?? Where do I inject? : r B12_Deficiency