King Harald was admitted to the hospital on Thursday when he had developed a fever. There it was established that he had an infection which was treated with intravenous antibiotics over the weekend.
The 85-year-old regent recently competed in the World Sailing Championships in Geneva, where he was skipper aboard the boat Sira. The Norwegian team finished tenth in the 8-meter class.
The next item on his official calendar is a meeting with the government on August 12.