A young mother and her partner who were found dead had low levels of drugs in their systems, an inquest heard.
Gaynor Robinson, 19, and Billy Applegate, 23, were discovered lifeless in the living room of their home in Providence Place, Norwich, on 1 June.
The inquest in Norwich heard a "get together" had been held there the night before during which drugs were taken.
The coroner said the amount of drugs in their bodies was too low to be fatal but the cause of death was unknown.
Mr Applegate and Ms Robinson were found to have small amounts of pregabalin (a drug used to treat epilepsy), methadone and alcohol in their blood.
Mr Applegate also had a small amount of cocaine in his blood.
Jacqueline Lake, senior coroner for Norfolk, said: "Because the levels are so low they are not expected to cause toxicity.
"I do not accept the cause of death to be mixed drug toxicity."
She said the witnesses' statements about the sharing of drugs at the property were inconsistent and unreliable.
She concluded with a narrative verdict which said the causes of the deaths could not be ascertained.
Correction 26 February 2020: An earlier version of this story stated that Ms Robinson had a small amount of cocaine in her blood. This has been amended to make it clear cocaine was found in Mr Applegate's blood.