I may be willing to try a beta-blocker, or even a drink or valium, but I lean more toward thorough preparatrion. I like the one person who practiced while stone cold so that jittery hands would not be a new experience on stage. Thank you for that suggestion!
During my better years of performing concerts I used all the tricks in the bag that I picked up from various mentors. Practicing in a pitch black room (i.e. isolating motor memory), on silent keyboards, left hand memorized by itself, copying scores and cutting them to pieces and making a pile on the left side of the piano, starting on the measure I pull out from memory, then redoing the pile starting on the measure BEFORE the one I pull, a great deal of mental practice (hours of it!) - if you cannot play through all your pieces slowly mentally while feeling and hearing every single note, finger, and key, slowed down if need be, then you do not know all of it thoroughly!, and last but not lears schedule enough try-outs and run-up performances before more important ones. Also perform all pieces on as many different instruments as you can and in as many different sounding rooms and halls accoustically as you can under all kinds of lighting conditions, including no lights. Also do recording sessions before an important recital. Knowing that you already have it all well done on CD will take some pressure off the live recital that follows. Then record the live recital. If you do it in that order, most likely the live recital will be the best recording after all. And indeed play a lot for people and keep doing so on a regular basis. Performing will become routine, and that is what you need.
I once saw an organist get a relatively low grade due to sheer poor preparation. He scheduled a Bach Triosonata at the end of the program (not wise mentally...) and did not do any tryouts or smaller concerts before his conservatory final exam. He was worth a high grade qua talent, but got stuck with a lower grade, very unfortunate.
If in spite of preparations as thorough as possible as described above you still end up with anxiety (if I am not mistaken Arrau, doubtless among others, was known for serious performance anxiety) one last thought you must always keep in the back of your mind in the end: do not ever stop playing, keep going, jump to practice points, or improvise, but do not ever give up during a live performance, audition, or competition. Always go all the way through it and take that bow. Then later go to the recording with the score and fix the weak spots in your momory. Also take some moments for quieting yourself down, slowing down breathing, and focusing concentration, before you start playing. One great teacher I had also suggested not programming fragile things at the beginning of a recital. A good solid fortissimo opening makes it a lot easier to get used to the piano, the accoustics of the hall, the audience, and buys you time to get settled in on the stage before you do the more intricate and other difficult things.