Queensland's mental health services have come under fire after multiple deaths at a Brisbane hospital.

An independent review has been launched after three people died by suicide in the past 16 months at Prince Charles Hospital's mental health unit.

Another two patients harmed themselves at the 60-bed unit during that period, most recently in April, according to an ABC News report.

The Royal Australian and New Zealand College of Psychiatrists (RANZCP) said Queensland's public mental health sector could not keep up with a rise in more complex cases.

"The public sector services are just so overwhelmed that unless you're very psychotic or dangerous or suicidal, your chances of them being able to handle and manage your case is reduced," Queensland branch chair Brett Emmerson told AAP.

"Some of these incidents arise not due to staff incompetence but it arises due to inadequate staffing, increased complexity and indecision by governments to provide the amount of resources needed to actually do their jobs."

Health Minister Shannon Fentiman on Wednesday confirmed the review was under way and set to be finalised mid-year.

She said Queensland Health would be ready to implement recommendations from the investigation.

"It's always incredibly distressing to lose a loved one and we're working very closely with those families as part of this review," she told reporters.

Ms Fentiman said there had been a clinical review into the deaths and some improvements had already been made.

She said frontline staff numbers had been bolstered and a new short-stay, crisis stabilisation unit was set to open at Prince Charles Hospital in September.

However, Professor Emmerson said poor planning had led to a lack of experienced public mental health staff.

"We're seeing more people, they're sicker and they're riskier," he said.

"There's also a shortage of mental health staff, particularly psychiatrists, leaving the public sector.

"I don't think governments have adequately planned the mental health workforce."

He said Queensland had a mental health planning unit from 2007 to 2012 that successfully recruited from medical schools.

"But that was lost around 2013 in the (then premier) Campbell Newman cutbacks and it's never been revived," Prof Emmerson said.

"Around 10 to 15 years ago we had a lot of inpatient nurses with 15 to 20 years' experience.

"You go into the mental health units now and their most experienced staff will have three or four years."

Ms Fentiman said there was an increasing demand for mental health services in Queensland.

However, she said the state's mental health care had come "an extraordinarily long way".

"I think for many decades there was a whole lot of stigma and shame around talking about mental health," she said.

"That meant that governments, I don't think, kept up with funding the services appropriately but that has really turned around here in Queensland."

Opposition Leader David Crisafulli said mental health was in crisis.

"The pressures that have built in society have reached the point where people are falling through the cracks," he told reporters.

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