A drug user died after taking more than four times the potentially fatal amount of methadone, an inquest heard.
Thomas Horgan, 46, died at a flat in Sutton in November last year having taken a huge dose of the heroin-replacement drug.
An inquest at Croydon Coroner's Court on Thursday heard Mr Horgan, originally from Cork in Ireland, was found by his partner slumped on a sofa at a flat in Violet Close, North Cheam, on November 9.
His partner called for paramedics but they could not save Mr Horgan's life and he was pronounced dead at the scene.
Mr Horgan, who had been living with his sister in Chelsea and did not work, was largely clear of drugs but had been prescribed daily doses of methadone.
South London Coroner Roy Palmer said an autopsy revealed he had 1.79mg per litre of blood when anything above 0.41mg is considered potentially fatal.
He added: "That's more than four times the potentially fatal level. It's pretty high levels. With that amount of methadone in his blood there's not a lot anyone could have done.
"I guess he must have got an extra supply from somewhere."
Mr Palmer concluded Mr Horgan died from dependence on drugs.