The Irish Blood Transfusion Service (IBTS) is asking blood donors to attend donation clinics this week, as blood stocks are very low after the bank holiday weekend.
It said it has added five extra clinics around the country for this Sunday, 12 April.
The IBTS said it aims to have a seven-day supply at all times.
It currently has just over two days supply of O positive and just over three days supply of other key blood groups.
The IBTS said clinics this week are in: D'Olier Street, Stillorgan, Cork Centre, Naas, Kells, Stamullen, Tullycorbet, Newbridge, Tullamore, Westport, Galway City, Kanturk, Glanmire, Abbeyfeale and Limerick City.
It has contacted hospitals to advise that stock levels are very low and for them to actively manage stock to ensure blood is available for those who need it most.
The IBTS said that hospital demand for blood has been high, particularly during March.
This has coincided with bank holidays around St Patrick’s day and Easter, with some donors taking advantage of the holidays and good weather, meaning they have been unavailable for clinics during that period, it added.