An anti-psychotic drug may have contributed to the death of a woman at a private hospital, an inquest heard.
Katharine Stamp, 30, died at The Dene Hospital, West Sussex, in March 2015.
It is "more likely than not" the drug Clozapine may have been an underlying cause of death, a toxicologist told a coroner's court in Crawley.
The drug's risks only came to light within the past seven years and advice to medics should be updated, Professor Robert Flanagan said.
A post mortem gave Ms Stamp's cause of death of aspiration pneumonia, the court heard.
Professor Flanagan, an expert in Clozapine, said it is a "complicated drug," adding: "It is only in the last six or seven years we have become aware of the risks of pneumonia and the possible consequences caused."
Ms Stamp, who had been sectioned and admitted to the hospital in September 2012, had a history of periodic chest infections and coughs, the court heard.
It was "incredibly poor practice" that there were not measurements of the levels of Clozapine in Ms Stamp's blood, he said.
However, he said he was content with the dosages of the drug she received.
Clozapine was not found in excessive levels in her blood, the court heard.
Prof Flanagan said it is "easy" to look at records in the aftermath, but added: "It is much more difficult for a team on the ground to understand it all."
At the time her death The Dene was run by Partnerships in Care Ltd, but following a corporate merger in 2016 management was assumed by the Priory Group.
Ellie Stamp, 31, said her sister, known as Kate, had been her "comrade."
"I'm speaking to remind you all that Kate was a person with hopes and dreams and love," she said.
The inquest continues.