Health authorities are anticipating a major shortfall in blood donations when people are taking holidays between Christmas Eve and New Year's Eve.
The Australian Red Cross is running a "blood blitz" in the lead-up to Christmas and will open on   December 27 for the first time this year in an attempt to head off the annual shortfall that occurs over the holiday period. 
It needs more than 5000 Australians to give blood for platelets, including 1500 people in NSW, in order to prevent a critical shortage.
NSW spokeswoman Jemma Falkenmire said the service still needed ongoing donations as platelets only had a shelf life of three days and could not be stockpiled.
"A lot of people came in at the beginning of   December, so they're trying to do the right thing, but because we can't store platelets it doesn't help us all that much," Ms Falkenmire said.
Transfusions were prioritised in favour of people with threatening injuries, so the shortage would most impact cancer patients, she said.
These patients, who used about 35 per cent of all blood collected, needed platelets to prevent internal bleeding during chemotherapy.
"It's usually in quite severe cancer, where chemotherapy has wiped out all the bone marrow," Ms Falkenmire said. "If they don't have [transfusions] they're not going to die, it just means they're not very well."
There is a forecast demand for 9600 people to give of all types of blood, while only 7501 people have booked in.
Last year, the number of people booked in to give blood over the same period was 600 short of the required donations.
Bateau Bay resident Dee Edmondson, 20, will not be among those patients sweating on blood donations this year, following 12 consecutive Christmas holidays spent anxiously waiting on transfusions.
Diagnosed with aplastic anaemia at the age eight, she needed transfusions twice a week, but she could not count the number of times she was sent home because there was no blood available.
"It would always stuff up around this time," she said. "If I hadn't had transfusions I would feel quite tired and lethargic and I would get more symptoms. I bruised and bled really easily."
Last   November, she had a bone marrow transplant and has not had a transfusion since.
To give blood between   December 24 and 31, please call 13 14 95 or visit donateblood.com.au.