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. B12 Shots & B12 Injections: The Good, Bad and Alternative! 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) B12 Shots vs. IV Infusions: What is the difference? Integrative Medicine, Laser and Aesthetics How Quickly Does B12 Shot Work? Does It Help to Lose Weight?