Vitamin B12 shots Prescription injections used to treat severe deficiency, pernicious anemia, or absorption issues (e.g., Crohn's, gastric bypass). They provide rapid, 100% absorption directly into the bloodstream, bypassing the digestive system. B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics Thinking of a B12 injection for wellness? Here's what you need to know Vitamin B12 injections are prescription only medications and for good reason. They're intended to treat a clinically How to Give a B12 Injection: Step By Step Instructions