What Happens If You Inject B12 Wrong: 6 Red Flags Common Injections Cheat Sheet Save for Ward Rounds! Insulin Diabetes Subcut 0.51 unit kg Vitamin B12 Deficiency Neuropathy IM 1001000 mcg Tetanus Toxoid How to Give a B12 Injection: Step By Step Instructions 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 Created Equal Your Quick Guide to Injection Types , Ever wondered why some shots go in your arm muscle and others just under the skin? Heres the breakdown:, Intramuscular (IM)