system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does it hurt to rub salt into a wound?
gpt
Your nerves literally send signals to one other through salt, specifically sodium and potassium.  Adding a bunch of salt to the wound overloads local neurons with tons of sodium and they fire off like crazy.  That message travels to your brain, and the large amounts of stimuli are perceived as lots of pain.