More than 500 public hospital workers from across the Illawarra Shoalhaven Local Health District will join 22,000 of their colleagues across the state taking part in the industrial action.

The timing will be different across the state, with Health Services Union members at the district's hospitals - including Wollongong, Shellharbour and Shoalhaven - choosing to take the action from 10am to 2pm.

Hospital security, allied health, catering and administration staff, plus paramedics, are among the health workers taking part in the strike, with rallies planned at each site.

HSU NSW secretary Gerard Hayes said members had voted to take the action as a last resort, as part of their ongoing fight for increased security at the state's hospitals.

"The action will have an impact for hospitals, but we're trying to minimise the impact on patients," he said.

"It will mean for instance that no financial billing will be done during those hours; there will be a delay in cleaning beds once patients leave hospital; there will be delays in catering and security won't be on site.

"It will slow down the processes in each hospital, although patients needing care will receive that care."

Read more: Shellharbour Hospital security guard speaks out ahead of strike

Medical staff are not part of the action, although the NSW Nurses and Midwives' Association is publicly supporting the HSU campaign.

Paramedics will still respond to emergencies, but will remove billing information from paperwork during the four hours.

The union wants at least 250 more security officers stationed at hospitals across the state, as well as better training and enhanced powers for those staff.

"We want extra workers, extra training and a different approach to how security responds," Mr Hayes said. "We want people trained and educated to actively intervene and de-escalate situations.

"So if they see someone who's agitated they can talk to them and calm them down. If someone's on ice and aggressive they'll have the power to restrain or detain. If someone's drunk and abusive, they can remove them from the premises.

"At the moment, they don't have the training or the powers to do any of those things and need to call in the police."

Mr Hayes said escalating violence in hospitals was an issue not just for union members and other health workers, but patients too.

"It's traumatic for patients having to watch very ugly situations unfolding - and to sometimes become a victim themselves," he said.

"A healthy hospital is a safe hospital, and we are going to continue our campaign until this is resolved."

NSW Health Minister Brad Hazzard is calling on the Health Services Union to reconsider this week's strike action.

"I think the truth is anyone in the community would be concerned at members of the HSU going out on strike," Mr Hazzard told the Mercury on Monday.

"The HSU is one of the biggest unions in the country with members including paramedics, allied health staff and cleaners - a lot of very important staff who keep our health system running.

"So I'll be telling (HSU NSW secretary Gerard) Hayes that I'd be grateful if he could reconsider and allow the process to take place.

"I've also instructed the Ministry of Health to work with the union and try and find a way forward."

Mr Hazzard said he had a good relationship with the union and shared its concerns about violence in hospitals.

However, he would like to await the final recommendations of a state government review into hospital security before implementing further measures.

"The government appointed Peter Anderson - a former Labor health and police minister - to review security in our hospitals," he said.

"Mr Anderson is uniquely placed to understand the complex interface between health and security, and he provided an interim report in February.

"It makes sense to me to wait for the final report, within the next few months."

On July 16, HSU members voted unanimously to strike over fears about workplace safety.

A NSW Health spokesman said the department continued to engage with the HSU in relation to the issues that have been raised about workplace safety.

"NSW Health has sought the assistance of the NSW Industrial Relations Commission to reach a compromise position prior to planned industrial action by the HSU going ahead on August 1, particularly in light of the current winter volume of presentations at our public hospitals," he said.

"Local Health Districts and Networks have also put processes in place to minimise any disruption to services as a result of any industrial activity by support staff."

The matter is listed in the IRC on Tuesday for further hearing.