Murphy died of pneumonia, but could have survived if she had seen a doctor in time, a Los Angeles coroner has ruled.
Coroner's spokesman Craig Harvey added that iron-deficiency anaemia and "multiple drug intoxication" were secondary factors in her death.
The drugs were all prescription medicines. More details are due in two weeks when a complete report is ready.
The Clueless actress died in December, aged 32.
Source: Press Release