When is it advised not to drive before getting behind the wheel?

Driving should be avoided when experiencing side effects that affect vision or reaction time because these factors significantly impair a person's ability to operate a vehicle safely. When side effects, such as those from medication or illness, cause blurred vision, delayed reflexes, or decreased awareness, the risk of accidents increases dramatically. A driver needs to have full control over their cognitive and physical functions to make snap decisions and react promptly to changing road conditions.

Feeling tired can also impair driving ability but is not as immediate as the side effects that specifically hinder vision or reaction times. The excitement, while potentially distracting, does not have the same immediate and severe effects on driving capabilities. Consuming food, in general, does not typically impair one's ability to drive effectively; in fact, staying nourished can be important for maintaining focus and energy on the road. Thus, the presence of side effects that directly compromise essential driving skills makes that choice the most critical scenario in which one should refrain from driving.