Nursing staff who work with substance abuse in Boden, in the far north of Sweden, made a house call on Wednesday to meet with a 25-year-old man, wrote the Norrbottens-Kuriren newspaper (NK).
The man prepared a table of coffee, muffins, and buns, known in Swedish as a fikabord, however after consuming the sweet treats the staff members began to feel ill, and were later taken to hospital.
The 25-year-old is now suspected of spiking the coffee and the cakes, with local police raiding the man's house later on Wednesday and confiscating his muffins.
"Staff members have even had to take blood tests to see if there are drugs or any other foreign substances in their blood. It will take a few weeks before we get an answer," Per Finnberg of the local police told NK.
"If someone poisons someone by putting drugs in their coffee or buns it's classified as abuse."
Finnberg added that the suspect was already known by police.
Samples of the cakes have been sent to the Swedish National Laboratory of Forensic Science for analysis.