Laws prohibit possession or use of many drugs while on duty. However, possession and use of a drug given to a driver by a doctor is permitted if the doctor informs the driver that it will not affect safe driving ability. Pay attention to warning labels of legitimate drugs and medicines and to doctor's orders regarding possible effects. Stay away from illegal drugs. Don't use any drug that hides fatigue - the only cure for fatigue is rest.
Alcohol can make the effects of other drugs much worse.
The safest rule is don't mix drugs with driving at all. Use of drugs can lead to traffic accidents resulting in death, injury, and property damage. Furthermore, it can lead to arrest, fines, and jail sentences. It can also mean the end of a person's driving career. Once in a while, you may become so ill that you cannot operate a motor vehicle safely.