Driving with a heavy cold could be as dangerous as getting behind the wheel when you're drunk.
A new study showed that those who were under the weather had slower reaction times than people who had drunk up to four pints of beer.
A cold not only caused drivers to take longer to stop a car but made them drive too close to the vehicle in front and made them less aware of the danger of a collision.
And when they sneezed, they took their eyes off the road for up to three seconds.
"Having a cold is equivalent to drinking three or four pints and being over the limit," says Professor Andy Smith, of Cardiff University, who led the study.
"People with a cold had slower reaction times than those associated with drinking," he says.
"Colds slowed reaction times by 36 milliseconds. Yet consuming the amount of alcohol that would lead to a driving ban slows reactions by just 15 milliseconds."
While the physical symptoms of a cold are well known, researchers are increasingly looking at the effects it has on mental functioning.
In the study, 50 people with a cold were tested and the results then compared to results for a group who were not infected over the same three-month period.
Results show that alertness was reduced by a third in cold sufferers. The effects did not seem to be altered by the severity of the cold.
Other studies have suggested that when the body fights infection, it may affect the levels of key chemicals in the brain, causing changes in mood, memory and movement.
Prof Smith says: "People who drive when they have a cold need to know the risks."
- DAILY MAIL