Should I get B12 injection or use oral spray? : r B12_Deficiency Methylcobalamin B12 Injection in Beverly Hills, Arcadia and Los Angeles County California Infusion Centers Efficacy of different routes of vitamin B12 supplementation for the treatment of patients with vitamin B12 deficiency: A systematic review and network meta analysis Irish Journal of Medical Science (1971 ) 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.