THE family of a mother of two plans to sue a Melbourne hospital, alleging the 50-year-old started suffering a rare life-threatening condition after being given sedatives against the family's wishes.

Sunilta Prasad, who has a nervous-system disorder affecting her co-ordination and movement, was admitted to Broadmeadows Health Service last month so she could be assessed for a Department of Human Services home-care package.

But within three days of her admission in June and receiving the sedative olanzapine, her family says she has lost her independence and can no longer dress, feed or shower herself.

But the hospital denied the allegations of mismanagement and said she was receiving "the best possible care".

Her daughter Ravineetha said she feared her mother, who has cerebellar ataxia, would die in hospital. "she could still dress and shower herself, get in and out of bed before she came to hospital, and now she can’t even sit up by herself," Ms Prasad said.

"She’s traumatised, she hits herself, and is in pain every day.

"I’ve been ready to say goodbye to her because I don’t believe she can live through this."

Ms Prasad said after the family questioned doctors about their mother’s rapid decline, they were told the symptoms – including shaking, restlessness and fevers – were a result of her disease.

"I’ve seen her decline over the 15 years since she was diagnosed, but she’s never been like this," she said.

Ms Prasad said they had been given inconsistent explanations of their mother’s decline from the hospital, with a neurosurgeon admitting their mother was showing symptoms of neuroleptic malignant syndrome, a rare and life-threatening reaction to antipsychotic medication.

The family has filed a complaint with the Health Services Commissioner and has been through the hospital’s internal complaints process. A Northern Health spokeswoman said while she could not comment on the specific case there were "major inaccuracies" in the family’s claims.

Specialists had regularly updated the family about their mother’s condition.

Australian Patients Association chief executive Stephen Mason, whose organisation is supporting the Prasad family, said medical staff ignoring the advice of family members had been a common problem.