I don't think there is any real answer to the question, because there are just too many depends...what they use, how long they use, etc. I know for me my brother died in his early 40's due to hepatitis which he contracted from dirty needles. I am now dealing with my daughter who recently turned 19 and is now 7 months clean. I pray she is able to conquer her deamons and lives a long productive life. She has multiple problems (physical and mental) which complicate things. I was hard enough to lose my brother, I can not imagine losing my daughter.