For no obvious reason, this occurred to me today: that there's no real mention of drug addiction in the classical world.
It's not because of ancient drug laws, because there weren't any. Nor is it necessarily due to lack of drugs, although the choice was a lot more limited. Herodotus mentions that the Scythians used to throw hemp seeds on the hot stones of their steam baths. But nowhere does anyone mention Scythians becoming so addicted to their baths that they refused to leave them.
Alcohol was in plentiful supply, to put it mildly. In fact wine was probably safer to drink than the water. There were many drunken parties every week. But you're hard pressed to read of anyone being described as a drunkard until you get to Roman times.
The men of Alexander's army are described as frequently and copiously drunk, but this didn't stop them from conquering the entire known world. They performed very well indeed and don't seem to have craved drink so much as consumed it whenever it was available. Alexander did, in a drunken rage, kill one of his friends, but notice that even while blind drunk he was functioning quite well.
Men like Alcibiades were famed for their dissolute lifestyles, but no one suggested for a moment that their bad habits impaired their function. Quite the opposite in fact; men marveled that Alcibiades could live as he did and not only still stand up, but also be a great leader.
Painkiller abuse was possible. Hemlock is a powerful painkiller if you don't mind teetering on the brink of death. (Sort of like a lot of modern drugs, really.) The number of people reported for hemlock abuse is, as far I know, zero.
Ditto for poppy juice, which is much closer to modern drugs. They knew how to make it, and there's speculation it may have played a part with some oracles, yet I can't think of an instance where anyone wrote, "So-and-so was addicted to the juice of the poppy."
Why the lack of junkies? It might be because junkies don't tend to make it into history books. Yet there are other periods when such people did. It might be because natural selection eliminated addictive personalities very quickly in the ancient world. My own theory, formed after at least ten minutes of deep thought, is that the ancient Greeks were simply so into looking after themselves physically, and worshiped good physical condition to such an extent, that anyone who deliberately neglected their own health was simply lower than low. I can't imagine a classical Greek forgiving anyone for substance abuse. The society pressure to not do it was just that much greater.
(Of course, now that I've mentioned it, someone will probably come up with a hundred famous classical junkies...)