TweetI GOT A BAD ONE SPENT A WEEK IN THE HOSPITAL.ITS A INFECTION WICH HAS ALOT OF PUSS IN IT .ITS CAUSED FROM BACTERIA WETHER THE NEEDLE WAS DIRTY OR THE SITE WHERE YOU INJECTED GOT INFECTED OR YOU HAD GEAR THAT HAD BACTERIA IN IT. ALWAYS SWAB THE AREA BEFORE YOU INJECT AND AFTER YOU PULL OUT PUT THE ALCOHOL SWAB ON THE AREA AND PUT A BAND AID ON IT.JUST BE CLEAN AND KNOW WHAT TYPE OF GEAR YOU ARE USING. THE AREA WILL SWELL UP BE RED AND HARD AND USUALY GET A FEVER.