According to the study,
such as a stuffed-up head, grogginess and sneezing have the same impact on people’s abilities as a level of alcohol close to or at the drink-drive limit.
In the research, for Lloyds TSB Insurance, one hundred drivers with a range of conditions including colds, stress and and 50 who were healthy were put through a hazard simulator test, reports the BBC.
From the analysis, the study revealed that drivers with colds scored, on average, 11 percent worse - equivalent to the effect of a double whisky.
The study, carried out by PCP research agency, looked at 60 people with colds and flu as well as 40 with other conditions including premenstrual syndrome.
They said that applying the 11percent effect to reaction times would add 1m (3.3ft) to stopping distance if travelling at 30mph (48km/h) - on top of a normal distance of 12m (40ft).
It would add 2.3m (7.5ft) onto the normal stopping distance of 96m (315ft) if travelling at 70mph (113km/h).