Treating patients experiencing delirium with antipsychotic medication is doing "more harm than good", according to the findings of an eight year trial.

Antipsychotic medication typically used to treat seriously ill or dying patients with delirium is ineffective at best and hastens death at worst, suggests new research.

Such medications are commonly prescribed for patients with delirium but a world-first trial has raised concerns about their safety and efficacy.

The eight-year trial of patients with delirium in hospice and palliative care found patients were better off taking no medication for delirium than taking either of the commonly prescribed antipsychotic medicines risperidone and haloperidol.

"We found that not only do the drugs not work, but they actually make people worse by prolonging their delirium," said Professor Meera Agar, a palliative medicine physician in the UTS Centre for Cardiovascular and Chronic Care who led the study.

Two hundred and forty-seven patients with a mean age of 79 took part in the trial. Most (88.3 per cent) had cancer.

Thirty-four participants died during the study period, nine in the placebo group, nine in the haloperidol group, and 16 in the risperidone group.

For overall survival, those receiving risperidone were 29 per cent more likely to die versus those receiving a placebo, while while those receiving haloperidol were 73 per cent more likely to die.

Published in the journal JAMA, the trial was not designed to determine links with mortality.

But given how many patients in hospital have delirium, many people are at risk, said Prof Agar.

Professor Agar said the findings are a call to action on one of the most important, yet under-recognised, medical emergencies in Australia.

Delirium is an acute, and often frightening, condition causing changes in behaviour, communication and perception.

Often people will see things that are not there, like spiders crawling up walls.

Up to one in six patients with an advanced illness will experience delirium during a hospital stay and the figure is even higher for people in palliative care.

Most patients recall the traumatising experience long after the event and relatives who witness their loved ones suffering from delirium report its devastating effects.

Professor David Currow from Flinders University, principal investigator for the Palliative Care Clinical Studies Collaborative (PaCCSC) which conducted the study, says the practices currently used to treat people with delirium are "causing more harm than good."

Identifying delirium early and treating the underlying causes reduces symptoms of distress better than an antipsychotic medication does, the researchers suggest.

They say simple things such as ensuring people wear their glasses and hearing aids, are regularly oriented to the hospital environment, are kept hydrated and well-nourished, and have enough sleep can prevent or better treat delirium in many people.