Has medication with benzodiazepines a beneficial or detrimental effect on car drivers, or is alcohol still the villain?

There are groups in the community who claim that road safety can be improved if patients who receive benzodiazepine tranquilizers are prevented from driving a car. These groups disregard the fact that there exists no study to show that these drugs are a causal factor in crashes. This paper -will mainly review the effect of diazepam which is one of the older compounds.