Mel, many with tics/tourette use magnesium sulfate creme too.
it really seems to calm tics.
I make my own but I know a lot of people use the Kirkman's (it just has other stuff in so I go the purist route like mrsD's recipe )

the creme also a good quick way when one doesnt have time to do a full tub epsom salts soak or footbath.

The magnesium and sulfur really do work wonders for my arthritis in feet and are an almost instant relaxant and soother for my son's tics and the musculo-skeletal aches that come from them, and I believe there are also detox benefits from the tubs and footbaths