Safety experts found a dramatic increase in poor driving when victims of a cold were subjected to scientific tests.

Reactions times dropped sharply and sudden braking became much more frequent, as the motorist was less aware of surrounding traffic, while cornering also became erratic.

Driving ability was estimated to drop by over 50%, the study found. This is the equivalent of downing over four double whiskies,* a level of driving ability that an insurance company would expect to lead to an accident.

Insurance company Young Marmalade carried out the research in association with Halfords using a black “telematics” box, which records drivers’ speed, braking, and cornering.

“This small-scale trial provides a warning for motorists,” said Nigel Lacy, Co Founder of Young Marmalade. “ A heavy cold can impair a driver’s mood, concentration and judgement.”

There aren’t official figures for accidents caused by sneezing, colds and flu symptoms but the insurance industry suspect motorists are responsible for a thousands of prangs when they are under the weather.

The findings back up work done by Cardiff University Common Cold Unit** which showed that those with colds and flu suffered from poor reaction times and alertness and were a third more likely to hit the roadside kerb.

Halfords Winter Driving Expert Mark Dolphin said: “We want our customers to stay safe. You shouldn’t drive if you are not feeling well. The best place to be when you have flu or a heavy cold is at home, but if you really must go out, get someone else to take you and avoid driving.

“Other drivers should be aware of those around them.”

Added to this Police warn that drivers getting behind the wheel while suffering from a heavy cold could be prosecuted.

PC Steve Rounds, of the Central Motorway Police Group said: “Sneezing can be very violent, especially with a severe cold and causes the sufferer to close their eyes temporarily.

“Commencing a journey in such a state would certainly be irresponsible and could be held as an aggravating factor in any accident that lead to a death or serious injury, turning a careless act into a dangerous one and thereby exposing the driver to a charge of causing death by dangerous driving.

Police also warn that some over the counter medications can cause drowsiness and hamper driving ability. If a person is rendered unfit to drive because they have taken medication, then they commit the same offence as if they had taken illegal drugs such as cocaine.