Kissing an injured area can reduce pain by activating touch fibers and positive emotional salience.

“Well, OK, I think an important point to ground here when it comes to the experience of pain is that everything, when we say psychological, means neuroscience. I know you know. But it is accurate still. It is psychological, but it is neuroscience based. I mean, they're really becoming one and the same. But to answer your question, yes, by kissing it, you're activating touch fibers. We can also agree that there's a positive emotional salience that's associated with that. And that positive emotional salience is reducing pain too.”