The Irish Nurses Organisation (INO) has said A&E staff are facing into their worst time of the year.
The nurses union said up to 70% of all A&E cases over the Christmas period are alcohol related.
It said security must be stepped up to combat drunk patients who intimidate nurses, by shouting and spitting at them as they wait to be seen.
Liam Doran, chief executive of the INO, said health employers are not doing enough to protect staff.
He said that aggressive behaviour is particularly threatening for females.