There are serious risks in taking medication if you happen to drive a lot. In many cases psychotropic medications have been the cause of accidents, since they tend to induce a state of somnolence, even though you may not consciously feel tired.
Barbiturates and tranquilizers affect motor coordination and reaction time, and severely limit your driving ability.
Neuroleptic drugs inhibit your ability to process information.
Analgesics reduce vigilance and reaction time, and affect memory. Doctors advise patients who have been anaesthetized to wait 24 to 48 hours before driving.
Antidepressant drugs have not been shown to have a significant impact in driving ability.
Amphetamine-type drugs, which are often used by persons who drive for long periods of time, also reduce vigilance and concentration, especially if taken for extended periods.
Even non-prescription drugs (cough remedies, pain killers, allergy medication, pills to fight nausea, hypotensors and drugs to treat diabetes) are suspected of inhibiting the alertness of persons behind the wheel.
And finally, alcohol, which as you probably know is a danger to driving in itself, can multiply the harmful effects of any of these drugs. (Tobacco does not seem to have any negative effect on driving skills).
Driving ability can be improved by ingesting more polyunsaturated oils and most B-complex vitamins.