Receiving an injection is read as something being put into you from outside — help, influence or change you did not fully choose. Dream books also see in it a hard moment accepted for the sake of healing. Fear of the needle points to dread of a small pain that stands between you and something better. Giving someone an injection is read as wanting to fix or influence them. Being injected against your will suggests feeling that others are pushing their ideas into your life.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.