Was it injected by itself? If so it is the Benzyl Alcohol that causes that. I started mixing mine 50/50 with some other oil that doesn't have BA in it and it was virtually painless. But I have had an abess before that was from dirty gear. It wasn't T-400 it was some well known not so well made Vet. testosterone blend. I sterile filtered it and never had a problem with it since.