How Long Does It Take Vitamin B12 Injections to Work? B12 Injections for Weight Loss: Spa Black's Guide Gym goers spending monthly on vitamin B and C injections Have a f*cking word with yourself. Both are water soluble, so don't stick around for long in your system (12 14hrs) hence How to Boost Immune System with Vitamin B12 Injections Main benefits of B12 injections 1) Increased energy & reduced fatigue B12 helps convert food into usable energy Deficiency often causes tiredness, weakness, and low stamina 2) Healthy red blood cells Prevents Vitamin B12: How Frequently Should I Get It? URBAN Medical Fishersville, VA and Gilbert, AZ