From Longman Dictionary of Contemporary Englishdrug/dope/cocaine etc fienddrug/dope/cocaine etc fiendsomeone who takes a lot of illegal drugs → fiend
Examples from the Corpus
drug/dope/cocaine etc fiend• It was bad to see him that way, angry and shivering a little like a dope fiend.• We pour another glass and vent our spleen on drug barons and dope fiends. 