Under what circumstances are you permitted to use drugs while driving?

Using drugs while driving is strictly governed by safety regulations due to the potential impairment they can cause. The correct understanding is that drivers should not use drugs, whether prescription or over-the-counter, when operating a vehicle. This is because any substance that affects your ability to drive, regardless of its legal status or whether it's obtained with a prescription, can compromise safety on the road.

Even over-the-counter medications can cause drowsiness or other side effects that degrade your driving capabilities. Therefore, it's essential to understand that driving under the influence of any such substances is not permitted. This means that there is no circumstance where using drugs while operating a vehicle is legally acceptable; hence, the correct answer reflects the stringent regulations regarding drug use and driving safety.