Not all vitamins are created equal. Oral supplements have to pass through your digestive systemlosing potency along the way. IM injections deliver nutrients directly to your bloodstream for faster, more Vitamin B12 Injection Dosage for Adults: 7 Key Medical Guidelines Liv Hospital B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics How Often Can I Take B12 Injections? B12 Injections at Home Safety Guide for Self Administration Infusion For Health How to self inject intramuscular vitamin B12 Overview Guy's and St Thomas' NHS Foundation Trust