There are only a few situations in which "no-harm torture" is used, for example, when the victim(s) will be released after torture and there must be no obvious signs of torture that could be shown to police or whoever. If you go to police after a "no harm" interrogation, most likely you will be seen as insane or delusional. In no harm cases the victim will likely be given scopolamine and/or some other drug. There is lots of info on this drug in the usual places. BTW, your captors are not going to tell you whether you are getting the "no harm" version and there are plenty of ways to hurt you that do not leave a trace.

If you're unlucky enough to fall outside the "no harm" category, your captors can do whatever they like to you and robably will. I believe that some agents are told in training something like, "Everyone talks in the end so go ahead and tell some previously concocted story that reveals as little damaging info as possible. You are fucked anyway at this point and will either be killed or held in case you might reveal/confirm something useful later. Thank you for your service.

A word about waterboarding: It's not going to kill you but you will be convinced that it will. Good luck.