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. Vitamin B12 Injections vs. Supplements: Which is Right for You? Benefits of a Vitamin B12 Injection, Vitamin B12 injections are commonly used for people who are deficient, struggle to absorb B12 from tablets, or require a faster and more effective boost., Helps Compounded Methylcobalamin (Vitamin B12) Injection, 5mg mL How Often Can I Take B12 Injections?