Dreaming of injection is a bad dream as per dream interpretation and meaning. It means you will have to soon face something that you might have dreaded or was running away from. It also means the task is simple but you are thinking it is very difficult and not doing it.
Dreaming of injection also means that you have to depend on someone else to do some ugly work of yours. You do not want others to know about it.
The dream also means that if you can withstand small pressures and pain then there will be progress and happiness. You are not taking that small risk which might change your life.