Aspecial danger of drug use is that you

A special danger of drug use is that you can never know when it's unsafe to drive, and may not realize you are impaired.

Explanation:

The use of drugs represents a damage to health by several factors. On the one hand, it generates addiction, that is, the need to consume more and more often and in greater quantities the addictive substance. On the other, it is well known that these substances cause damage to the organism, in very different ways depending on which substance is ingested. But also the use of drugs generates indirect damages, since by altering the mental faculties of the person who consumes, it generates a behavior that can be reckless or violent by the addict, with the consequent situations generated by this type of behavior and its implications for the addict and for other people.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

answer; scientific;