Depends on the drugs. If you think anyone who is reasonable in their head takes fentanyl (which is 50 times stronger than heroin and can be incredibly easily overdosed on because they are packaged in 24 hour slow release plasters and additionally is either stolen from the healthcare system, sometimes actually ripped off from elderly patients, or bought from mexican drug cartels) then you'd be wrong.
Fentanyl is a last resort painkiller that is extremely heavily regulated in other countries and prescribed for things like tumor pain and heavy burns. It's not a regular painkiller, it's a narcotic. If you dose it high enough it can be used during anesthesia.
