The city coroner has urged people who have evidence of people dealing drugs to go to the police.
He made his comments following the death of 20-year-old Paul Adams, who was found dead at a friend's home last October.
Aidan Cotter said Mr Adams, of no fixed address, died from bronchial pneumonia associated with multiple consumption of drugs including methadone and morphine.
In recording that he died from abusing drugs. Mr Cotter told family members: "If you know who supplied them it is your civic duty to tell the police so that can prosecute.
"There are people who deal in drugs and get away with it because the police do not have the evidence to prosecute them.
"If you have the evidence tell the police and have them prosecuted. If you go out and tell people what happened to Paul perhaps it will help stop someone else taking drugs."
In a statement, mother-of-two Emma Toms said Mr Adams, a carpet fitter, had come to her home in Moors Lane, Northfield, on October 3 last year and after eating a meal together he had gone to sleep on the settee.
She said the following day she was unable to wake him and paramedics called to the address found that he was dead.
She said that Mr Adams had previously admitted to her that he had taken some anti-depressants as well as taking a couple of lines of heroin.
Pathologist Dr Joseph Newman said there was evidence that Mr Adams had taken ecstasy, cocaine and cannabis.