Lynda Clifford, 30, died in the lounge room of her mother's Port Kembla home in November 2009, just months after she was prescribed new anti-psychotic and anti-depressant drugs by Wollongong Hospital's mental health unit.

Deputy state coroner Ian Guy found the mother of three had died from respiratory depression, as a result of the interaction of the cocktail of medications in her system.

Delivering his findings earlier this month, Mr Guy noted there had been no substantive communication between the hospital or the Lake Illawarra Community Mental Health Service (CMHS) with Ms Clifford's private psychiatrist and general practitioner.

He also found the unit had failed to adequately communicate with Ms Clifford's family or divulge her treatment plan, particularly the intention to reduce the anti-psychotic drug Clopixol as another took effect.

Mr Guy told the inquest it was not a case of Ms Clifford inappropriately accessing medication intended for others, ruling out that she had accidentally overdosed or planned to take her own life.

"The methadone, anti-psychotic and anti-depressant medications ... had been prescribed for her," he said.

Ms Clifford, who had long battled with mental illness and illicit drugs, was admitted to the mental health unit in August 2009.

She was prescribed new anti-psychotics and anti-depressants at the end of her stay and was ultimately taking six different medications.

A treatment plan, explaining the drugs, was created but the treating psychiatrist at the hospital failed to communicate the document to other practitioners responsible for Ms Clifford's care, the inquest found.

Ms Clifford returned to her family but her mother, Lyn Rogers, soon saw a significant decline in her health, noting that she appeared heavily sedated and needed help with basic tasks.

The inquest heard it was unusual for an outpatient to be simultaneously taking three anti-psychotic drugs, as Ms Clifford was for a significant period of time, despite her care plan indicating she was to stop the Clopixol and slowly lower the dosage of another drug.

But Ms Clifford was given Clopixol another four times after she was discharged and the other medication was never reduced as the CMHS, which had since taken over her treatment, was never given the plan, the inquest was told.

Mr Guy said the absence of communication was symptomatic of the compartmentalised approach to medical care apparent in the case.

"It runs counter to a most important aspect of patient care - namely communication - not just to the patient but also to other doctors."

Mrs Rogers was also not provided with a discharge summary for her daughter and was merely told Ms Clifford would be a "different person" with the new medication.

Mr Guy said the failure to provide the summary directly contradicted a state health policy directive requiring the development of a care plan and its distribution to the patient and, with consent, their family.

He called for a review of the directive, particularly given that the region's local health district also indicated it did not provide plans to patients.

Mr Guy also found the Wollongong methadone clinic, which had been treating Ms Clifford since 2008, was not sent a copy of the care plan, despite the fact that there was a moderate risk of interaction between the medications and the methadone.

Both Ms Clifford's GP and former psychiatrist also did not receive the treatment summary and failed to adequately communicate with the hospital about her prognosis, the inquest found.

Mr Guy made several recommendations, including asking the state minister for health to consider a review of care-plan procedures and the creation of a standard document about treatment for patients and their families.