Patients abusing staff at Royal Melbourne Hospital's emergency department are often fuelled by methamphetamines, or ice, according to a new study.

Methamphetamines are fuelling violence against Melbourne hospital staff more than any other drug, according to a new study.

The world-first study by Melbourne Health and the University of Melbourne involved taking 229 saliva samples from patients responsible for attacking staff at the Royal Melbourne Hospital emergency department over a six-month period.

The tests uncovered 40 per cent of patients tested positive to drugs and of those, 92 per cent were positive for methamphetamines.

Researchers had to get ethical approval to collect the saliva as they tested unconscious patients as well as those who had been chemically or physically restrained.

Professor George Braitberg from Melbourne Health said he wasn't shocked by the results.

"We've always been aware that there is an increasing prevalence of methamphetamines and patients with agitated behaviour coming into emergency departments but I guess this is the first time we've been able to quantify how big the problem is," he told reporters on Wednesday.

"I wasn't surprised but I thought it would be a surprising result for the community."

Despite working during the heroin epidemic of the late 1990s, Prof Braitberg has found ice users more violent than other drug users.

"When someone takes methamphetamines they get hyperactive and hyper-vigilant and that's when the aggression and agitation can come out," he said.

Of the 80,000 admissions to the Royal Melbourne Hospital annually, researchers said it could be that up to 3500 patients who present with acute behavioural disturbance such as aggression are on illicit substances.

To coincide with the research, the Royal Melbourne Hospital released horrifying footage showing drug-affected patients throwing chairs, hitting hospital staff with computer monitors, punching them and spitting in their faces.

Nurse Ben Smith said while he enjoys working in the emergency department, he has been confronted by frightening and dangerous situations.

"I've been threatened, people throwing punches. I'm lucky to have never been injured," he said.

"It can also be really challenging to be told that someone's going to come and kill you. The verbal threats for our staff are often as distressing as some of the physical threats."

Premier Daniel Andrews said tackling the ice scourge remains a priority for the government, which has already upgraded security at some hospitals and provided additional treatment beds for drug-affected patients.

"(Ice) turns people into violent offenders that often bear no relation to the way they would conduct themselves normally ... it effectively turns people into absolute monsters. It is a wicked drug," he told reporters.