How Quickly Does B12 Shot Work? Does It Help to Lose Weight? Does Vitamin B12 Keep You Awake at Night? When to Take It Performance Lab Vitamin B12 Injections: What You Need To Know Your body needs vitamin B12 to keep blood cells healthy and to make your nerves work right. But what happens when you run low? Here are some signs: https: wb.md 3OUOc1J B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics