Why Do I Feel Worse After My B12 Injection The look of surprise never gets old when we do B12 injections and it doesnt hurt , B12 is a great vitamin to increase energy, reduce fatigue, improve nerve function, and so much more! Thank you to Feeling exhausted, run down, foggy or low this winter? Cold weather, darker days and busy schedules can drain your energy fast and that's where a B12 injection can make all the difference Understanding the B12 Vitamin Shot: Benefits, Risks, and Dosage Guide