A coroner is warning people on medication not to exceed their prescribed dosages.
A Dunedin woman, Heather Blackmore, was found dead in her bed in May 2010, the morning after her flatmate saw her taking large quantities of pills.
A report by Dunedin coroner David Crerar says pathologists found enough anti-depressants in Ms Blackmore's body to cause her death.
She was also taking prescribed anti-convulsant and anti-psychotic medication.
Mr Crerar says Ms Blackmore was not considered to be suicidal by her doctor and it is unlikely she took her own life.
He says she may have deliberately taken more pills because of severe symptoms, or swallowed the higher dose by accident.