The Queen, who celebrated her 73rd birthday on Thursday, was taken to the Karolinska University Hospital in Solna late last night.
Royal Court press chief Margareta Thorgren said that the Queen had been suffering with a cold for some time and had reported feeling dizzy during the evening, reports news agency TT.
As of two o'clock on Saturday afternoon, Queen Silvia is still at Karolinska and the court does not yet know how long her stay will last.
“The latest report from the doctors is that the Queen is feeling well, but she will stay at the hospital overnight as a precaution,” Thorgren said.
The Queen's youngest daughter Princess Madeleine accompanied the her to the hospital and was also there during the night.
The rest of the royal family has been informed, with a number of family members already gathered together, according to TT.
As of two o'clock on Saturday afternoon, the Queen is still at Karolinska and the court does not know how long she will remain.