If you prick yourself with a needle from an insulin syringe that had not been inside anybody in the last six months, the risk of infection is still present, but different compared to if it had recently been inside somebody. I am picturing in my head a syringe with needle that has been sitting on some counter. If this is the case, then the risk of infection is probably there because the needle is slightly dirty. The first question I would have for you is if you recently had a tetanus shot. If you have not had a tetanus shot in the last five years, then I would suggest that you consider getting one that your primary care doctor
's office. Most viruses that can be transmitted with the dirty needle required transmission shortly after the needle has been used. I do not think that most viruses can survive on the needle for six months outside of any body. However, I would probably consider asking the individual use the needle if they have ever been tested for HIV. Depending on that individual's risk factors for HIV, I might consider getting tested. Since you had no bleeding
or scratch marks from the stick, the depth of penetration is likely small and you are likely to get better with no intervention at all. However, I would suggest that you schedule an appointment with your primary care doctor so you can have the area examined to be sure.