Narco-mist

Narco-mist was sprayed on the body of an injured to help speed their recovery. It was a reddish mist of chemicals. The patient does not feel any pain when used. This spray was once used on Han Solo after his gladiator fight: The Big Game staged by Simon Greyshade, during his stay on the space station The Wheel.

Source

 * Marvel Star Wars 21: Shadow of a Dark Lord