Okay here is the thing ....ur friend have a painkiller addiction .....this kind of medicine create a sense of euphoria....meaning u will crave it......just like any addiction ...alcohol or drugs....actually they are called drugs right?........so ur frnd need to rehab...but not necessarily rehab center but try to withdraw from it as soon as possible....chances are he/she started it to get rid of stress and anxiety ....so get treated for that.......here in ethiopia awareness abt mental health is little so people are getting in trouble each day.....anyways u can make sure of its addiction here https://www.webmd.com/pain-management/features/painkiller-addiction-warning-signs and see how to withdraw from it on google