Emergency department (ED) nurses plan to strike next week after rejecting proposals brokered by the Workplace Relations Commission to resolve the overcrowding issue.
Members of the Irish Nurses and Midwives Organisation (INMO) rejected the proposals by a margin of 58pc to 42pc.
These were aimed at tackling staffing and patient safety issues in these departments.
Beaumont and Tallaght hospitals in Dublin will now be included in the first day of rolling strike action.
The INMO's executive council sanctioned the first day of strike action, involving two-hour rolling stoppages, for Thursday, January 14 - with subsequent days of action following later.
INMO General Secretary Liam Doran said it was quite clear that, in rejecting these proposals, its members - who work in 26 EDs nationwide - were stating that they had no confidence in senior management, at local level, to implement the proposed measures on a continuous basis.
"It was also obvious that members believe that there is a complete lack of awareness within senior management as to the compromising of patient care and safe nursing practice occurring on a daily basis - from the continuous presence of trolleys and overcrowding generally," he said.
"We will now consult with our ED representatives and strike committees on Thursday and prepare for the first day of strike action in seven hospitals, now scheduled for Thursday, January 14.
"Our campaign for a safer environment - for patients and staff - in the country's emergency departments will continue until our members are satisfied the necessary measures will be applied on a 24/7 basis."
Separately, Beaumont Hospital has asked the public and GPs to avoid visits to its ED where possible.
A statement from the hospital said that the ED is experiencing an unusually high level of patients presenting, combined with a higher than normal admission rate from EDs in the period since December 28.
Monday saw the highest daily number of attendances to the department in the past 18 months - almost double the average daily attendance rate.
The hospital said that all available inpatient beds are open, though six of these are closed because of nursing staff shortages.
"Beaumont Hospital is engaged in an active recruitment campaign," it added.
The HSE said last night that it remains hopeful that further discussions and clarifications over the next number of days, regarding the implementation of the escalation policy at local level, may help to resolve matters and prevent industrial action.