How Quickly Does a B12 Shot Work? Benefits & What to Expect Why Do I Feel Worse After My B12 Injection: 6 Body Reactions Feeling tired, low on energy, or just not yourself? A B12 injection could be just what you need. Vitamin B12 helps support energy levels, reduce fatigue, boost concentration, and support your nervous How Quickly Do Vitamin B12 Injections Work? Prime Aesthetics Why Do I Feel Worse After My B12 Injection? PA Relief