A coroner's court in London ruled that Winehouse was most likely killed by accidental alcohol poisoning, the Associated Press reports.
Three empty bottles of vodka were lying in Winehouse's flat, the court heard. She was found with 416mg of alcohol per 100ml of blood, the BBC reports. The UK's legal limit for driving is 80mg.
That amount was sufficient to kill her, the inquest ruled.
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Coroner Suzanne Greenway said:
"the unintended consequence of such potentially fatal levels was her sudden and unexpected death."
Winehouse's doctor, Christine Romero, told the inquest that the singer had been trying to quit drinking and not consumed any alcohol in the three weeks before her death.
The night before she died Winehouse was "tipsy but calm", according to Romero. The singer made no reference to suicide, the doctor said.
The inquest into Winehouse's death was initially opened in July, but then adjourned. It resumed on Wednesday.
A spokesman for the Winehouse family, Chris Goodman, said they were relieved to "finally find out what happened to Amy":
"The court heard that Amy was battling hard to conquer her problems with alcohol and it is a source of great pain to us that she could not win in time."
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