Blood supplies are running low in all of Sweden's three biggest cities, Stockholm, Gothenburg, and Malmö.
"The situation is serious," said Anna Wiberg, chief physician for transfusion medicine in the Västra Götaland region, which is home to Gothenburg, in a statement.
"When blood stocks get too low, large parts of the healthcare system are affected," she said.
The region is in short supply of blood types A and O, both negative and positive, as well as AB negative.
Because it is the peak summer holiday season, fewer people are donating blood. If levels continue to fall, planned surgeries may have to be postponed, according to Wiberg.
The situation is even worse in Skåne, home to Malmö, where there is an "acute shortage" of blood types O and A negative, according to the blood centre network Geblod.
Meanwhile, Stockholm requires urgent replenishment of types O and AB negative within the coming days.
English-speakers are only able to donate blood in Stockholm, Uppsala and Gothenburg.
The reason it's only possible to donate blood in Swedish in most regions is because the donor must fully understand the health declaration they must sign, which ensures the blood is safe.
In 2019, Stockholm became the first region in Sweden to translate the relevant material and train staff in medical English. But as healthcare is run at a regional level, it is up to individual regions to decide whether to make this possible in their regions.