Driving with a cold of flu can significantly impair driving, according to research done for Lloyds TSB Insurance Company. In the study, 100 drivers with colds, stress or headaches were put through a hazard simulator, and compared against 50 who were healthy, the BBC reports. Those with colds scored 11 per cent worse on average, about equal to the effect of driving after a double whisky. In a separate poll of 4,000 respondents, 22 people said they’d had an accident while they had a bad cold, and five while they had the flu. Cold symptoms are often aggravated when combined with medication, fatigue, or even a small amount of alcohol. “Safe driving requires concentration and good reactions, both of which are significantly reduced, even by just a mild cold,” says Dr. Dawn Harper, who suggests sufferers avoid driving until they feel better.