There are fears the holiday season will exacerbate a drop in the number of people donating blood.

The Australian Red Cross Blood Service says it needs about 200 more Tasmanians to donate in the next few days to ensure there is enough to meet patient demand.

Spokesman Shaun Iguanzo says there is normally a dip over Christmas, but it is especially bad this year.

"One blood product in particular, platelets, is incredibly vital to helping them make it through chemotherapy," he said.

"It's also the most short-lived blood product in terms of lifespan, only lasting five days.

"The public holidays fall during the middle of the week, people are inclined to take the days between the weekend and the public holiday as annual leave.

"In the case of platelets, the product lasts five days, so anything collected up until the end of today will expire by mid next week.

"If we don't have people coming in on New Year's Eve to give that blood product, there's a very real risk stocks of platelets will run low."

Mr Iguanzo says one-in-three Australians will need blood during their lifetimes, but only about one-in-30 regularly donates.