If in a dream to you give an injection, then in real life you need to give more time to own health. If dreamed you that you very much are afraid to give an injection, especially, if at the same time you see the huge syringe, then you are outright frightened of the state of health. However, most likely, your alarms are exaggerated. The dream in which you give to someone an injection, means that in the near future will ask you for the help and you will not be able to refuse.
Be sure and keep any other thoughts out of your mind before drifting to sleep as a cluttered mind can decrease the chances that you will remember your dreams upon waking. Also, focusing on remembering your dreams upon waking in the morning is another very important thing. This sounds very easy, but is often hard for some to do. Interpret a dream by "dictionary dream of interpretation"
When you very first wake up, simply think about your dreams. Don't allow your mind to drift off to other things, just lay there and think about the things you dreamt about the night before - dictionary dream meaning.