A friend? Just say its yourself.. probably not serious are you sure wasnt a miss? If it continues to swell and have pain id go check it out. Other drugs has more information, do a search this is a pretty common thread topic...
Edit: please avoid shooting in your wrist!! Your wrist and hands are the most nerve dense areas in your body considering how they are capableof such delicate motor functions. I got an infection in my wrist and had to have a plastic surgeon do the surgey to scrape the infection off the tendons due to the fact the plastic surgeons are specialized in dealing w delicate areas.
You may have hit a nerve, next time try different spots. Why are you shooting in your hands? Other veins blown?