Understanding The Benefits of B12 Shots for Weight Loss Vitamin B12 injections deliver high doses of this essential vitamin directly into your bloodstream for better absorption than oral supplements to boost energy, support red blood cell production and maintain nerve function. Cyanocobalamin vs Hydroxocobalamin (Vitamin B12 forms) Key Clinical Differences Hydroxocobalamin is preferred in: Pernicious anemia Severe vitamin B12 deficiency Neurological symptoms (subacute combined degeneration, neuropathy) Cyanocobalamin is Should I increase the dose or frequency of monthly 1000mg (milligrams) vitamin B12 injections for a patient with persistent low vitamin B12 levels?