How Long Do the Benefits of Vitamin B12 Injections Last? Vitamin B12 Injection Dosage Guide: 7 Essential Dosage Facts for Adults Liv Hospital B12 Vitamin Shot The Saint Louis Med Spa Vitamin B12 shots: Uses, benefits, and side effects B12 injections have lots of benefits from just 1 dose. A dose can be given every 6 months to boost benefits, unless you have a b12 deficiency or pernicious anaemia with proof 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