The temporary nervousness you experience is likely a mild side effect of Bluvit injection (Mecobalamin, Nicotinamide, and Pyridoxine). It may occur when the body responds to B vitamins, particularly Pyridoxine or Nicotinamide, which can briefly stimulate the nervous system or cause flushing and restlessness. In some people, anxiety related to receiving an injection may also contribute to these symptoms. Since it resolves within a couple of hours and you return to normal, it is generally not concerning, but you should inform your doctor if it becomes more frequent or severe.