Infections can come from many forms.. Dirty needles, poor grade drugs, and an area that was not cleaned properly. I have noticed that I can take all the precautions and I still get infected from time to time. The last time I got infected was about 4 hours after an injection, I jumped into a hottub and the next day it was sore as hell. I am assuming that the water was dirty. The thing you want to watch out for is a lump that hurts like mad. If a lump does not go away after a week, you might have to take some antibiotics. I have actually drained an absess by myself using an injection needle (clean one) and have taken out 10cc of puss. The next day it felt much better. But I would advise you that if you do drain it yourself, use a clean pin each time you drain, because the infection can get worse by using the same needle. Good luck.