Police are investigating after a truck left the road on the Owaka Highway, outside Balclutha, at about 12.10pm.
Bystanders who saw the incident said the truck's driver, a lady in her 30s, appeared to lose consciousness at the wheel in a 30kph roadworks safety zone near Silver Fern Farms Finegand freezing works.
The resulting low-speed crash into swampy ground on the opposite side of the road had left the driver dazed, but without obvious injury, they said.
Ambulance, police and two fire appliances from Balclutha were quickly on the scene, where treatment was given by Balclutha St John after removing the driver from her vehicle.
Police said no other vehicles were involved, and nobody else was injured during the incident, which they would continue to investigate.
