An urgent appeal has been issued for an additional 2,000 blood donations over the next four weeks.
The Irish Blood Transfusion Service (IBTS) says most groups in the national blood supply have fallen to under three days of stock.
The IBTS aims to have seven days supply but current levels - including O negative, A negative and B negative - are under three days supply.
O positive is also very low at 3.5 days.
IBTS Director of Donor Services Paul McKinney said August was a particularly busy month.
“There has been a consistently high hospital demand for blood over the summer months and in August we issued the highest amount of blood units to hospitals in over a decade," he said.
"This high demand has continued through September and with a bank holiday fast approaching we need to boost our collections by nearly 500 donations per week in all blood groups to be able to continue to meet the demand.
"High sickness levels, holiday travel combined with the traditional back to school demands, have all had an impact on donor availability throughout the summer and now into autumn".
A blood donor making a donation, 14-5-14. Image: Matej Kastelic / AlamyThe IBTS is asking regular donors who are texted for upcoming clinics over the coming weeks to make "an extra effort" to attend, especially in Dublin and Cork.
Potential new donors are being asked to visit giveblood.ie and take a quick eligibility test.
Mr McKinney said they would "particularly encourage new donors of African Heritage to join the national blood donor panel to help us diversify the donor base and get better blood type matches for patients."
A pre-amber alert letter was issued to all hospitals on September 27th restricting issues of certain blood groups.
This alert allows the IBTS to manage the limited blood supply available more effectively across the health service.
The IBTS says the need to issue an amber alert letter "would have an immediate implication for hospitals and for elective surgical procedures requiring blood support."
