Is It Okay To Use A B12 Injection With Insulin Syringes? 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 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 body but not all injections are the same. What Happens If You Inject B12 Wrong: 6 Red Flags