To dream that you are being injected for medical reasons indicates that you need to develop yourself on a mental and spiritual level. You are looking for an emotional uplift or need some time to heal. Alternatively, the dream may be a metaphor that you need to “inject” more energy into your walking life.
To dream that someone is forcibly injecting you represents your negative attitudes about a particular situation/person. It also indicates the influence of peer pressure working against you. You are recognizing that someone is forcing their negative and unwelcome views/values on you.