Police said in a statement that the driver, identified as a 53-year-old man from Lakemoor, will not be cited or charged. McHenry police spokesman Patrick Polidori told The Associated Press that he could not release more information about the man's medical issue.
Police said the pickup truck ran off the roadway in McHenry, about 50 miles (80 kilometers) northwest of Chicago, and struck a vehicle at the drive-thru window before colliding with the building.
Police said one person was trapped under the truck. Four people, including the truck driver, were taken to hospitals. A fifth person was treated at the scene.
The driver of the truck was treated for minor injuries and remained hospitalized Friday morning for observation, Polidori said.
A person in the car that was struck by the pickup was treated at a hospital and released, police said.