I've also used suggestion to help stop my girlfriends bleeding to surprising success (the doctor asked why the cut hand was so cold!).

If you do things like that I would take care to revisit the issue a few days or a week later to make sure that the blood flow in the hand is alright and the experience didn't taught your girlfriend to permanently have less blood flow in that hand. You might even measure the temperature in both hands with a thermometer.

Physical trauma + specific suggestion that solves a problem is a straightforward way to install long term behavior.