Most traffic crashes are the result of human error. Statistics aren't kept for innocent people injured or killed in accidents involving impaired driving. Because the presence of other drugs is not routinely assessed, the total percentage of those killed with a combination of alcohol and other drugs would be even higher. At highest risk are young people. Those between the ages of 16 and 19 are in the most danger.
Alcohol is the most widely used drug and the one most often linked to motor vehicle accidents.
Other drugs, however, and especially when they are combined with alcohol, can also interfere with a person's ability to drive. Proof of this was found in an Addiction Research Foundation study published in 1992 and based on research done at the Sunnybrook Health Science Centre's regional trauma unit in Toronto. Best advice for anyone taking any kind of medication is to ask a pharmacist or doctor about the effects on driving and whether even a small amount of alcohol will increase the drug's effect. DON'T, and certainly not if you intend to drive. Illicit drug users usually can't be sure what drug or drugs they are taking or of the dose they are receiving.