An 18-wheeler truck driver was injured when his vehicle overturned on the Garden Route, said Western Cape paramedics on Tuesday.

ER 24 spokesperson Tristan Wadeley said the truck was travelling towards George on the N2 freeway on Monday night when the driver apparently "blacked out" between Knysna and Sedgefield due to an allergic reaction to an unidentified allergen.

He was taken to the Life Knysna Hospital's intensive care unit with allergic shock and a fractured pelvis.

Two lanes on the N2 towards George were closed for several hours as a result of the accident.