Fast Relief, and Simple

From Surgeon's Blog:

...the subject was a simple procedure bringing rapid and dramatic relief, commenters have mentioned other similar interventions. Seems like a fun topic. Here's a list I can think of (a couple of which are those mentioned in the comments, by readers.) Anyone want to chime in with others?

Giving "Narcan" to an overdose patient: within seconds a moribund and blue, pin-point-pupilled addict is transformed to a yelling and screaming maniac.

Similarly: Dextrose IV for hypoglycemia rapidly raises from unconsciousness to lucidity.