It's usual seven day supply has fallen to four.
The Irish Blood Transfusion Service says it's struggling to maintain blood stocks and is under pressure to fill clinics.
It usually holds a seven day stock of blood, however after the Bank Holiday weekend, the reserve fell to just four.
The IBTS was forced to import 390 units of blood from the UK after a shortage at the end of last year.
Regular donors who are contacted by text are being asked to book an appointment as soon as possible.
Clinics will be held in Durrow in Laois, Edenderry, Birr and Tullamore later this month.
Barry Doyle of the IBTS says this is the first time this year that blood stocks have dipped to this point: