How to Give a B12 Injection: Step By Step Instructions B 12 (Methylcobalamin) Therapy MedClub by Dr Jenn What is the best route for administering vitamin B12: intramuscular injection or subcutaneous 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 body but not all injections are the same. How to self inject intramuscular vitamin B12 Overview Guy's and St Thomas' NHS Foundation Trust