Could we potentially....

I know this may sound stupid but if given enough time would humanity grow immune to the harmful effects of drugs?

I dot think so... but I have one question... what king of drugs are you talking about?

Doctors are constantly having to try and find anti-biotics for like the cold and things because the bacteria slowly adapts to the antibiotic causing it to become immune to it... I think humans will become extinct due to bacteria... They will soon become immune to whatever w throw at them... causing all sicknesses to become more dangeros... actually it's more of a thought... So actually... Instead of us becoming immune to the drug.. the bacteria does... I'm not sure about the other drugs though, like cigarettes and stuff.

I think intoxicants of any kind will generally have long term effects because of the way they actually work on centers of the brain.

The strength of this kind of effect is unlikely to be diminished through natural selection (Darwinism).

What is evolving in our species, though, is quite disturbing. Maybe another time.