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 ) Sublingual B12 vs Injection WhyNotNatural 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 ) Still taking vitamin B12 injections? Move over shot. A pill may be just as good. Dr. Leslie Greenberg's Blog Compounded Hydroxocobalamin (Vitamin B12) Injection