A vitamin B12 injection is a shot that delivers B12 directly into your muscle, helping your body absorb it quickly (especially if your body struggles to absorb it from food or tablets) Vit B12 INJECTIONS vs B12 Tablets ? Name Dose & Duration of B12 Tablets Dr Rupal Explains 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 ) 1 Energy You Can Feel Vitamin B12 helps your body turn food into usable energy. Low levels can leave you feeling constantly drained, no matter how much sleep you get. 2 Brain Doctor Reveals Facts About B12 Injections Vitamin B12 injections vs tablets: which is better for you?