How Often Should I Take Vitamin B12 Injections How Often Can You Get a B12 Shot for Maximum Health? 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 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 Injections for Aging and Longevity InVita Wellness