system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does medicine such like anaesthetic and painkillers make you constipated? What are the chemicals doing to your body to stop the poopin'?
gpt
Opiates (like morphine) basically act on the gut to reduce the movement of the gut that moves your poops along, reduces the secretions that the gut makes, and absorbs more fluid from the poop.

So it dries them out, and keeps them in a long time.