The Irish Blood Transfusion Service is calling on donors to make appointments to give blood as stocks run low across the main blood groups.
IBTS say there is currently three days supply and have issued a 'pre-amber alert letter' to all hospitals advising them of the situation and asking them to use blood "conservatively".
In a statement today the service said "bank holiday weekends are always difficult as our capacity to collect blood is reduced, the increased incidence of Covid-19 in the community as well as seasonal illness is having an adverse effect on donor attendance".
It said there had been an increased demand for blood over the summer months and into autumn, adding that Covid-19 had impacted donor blood collections.