Drug user and Doper

Drug user noun - A person who takes drugs.

Doper and drug user are semantically related in junkie topic. In some cases you can use "Doper" instead a noun phrase "Drug user", when it comes to topics like person addicted to narcotics.

Doper noun - A person who regularly uses drugs especially illegally.

Drug user and doper are semantically related in junkie topic. You can use "Drug user" instead a noun "Doper", if it concerns topics such as person addicted to narcotics.