5 things
1) DRICLOR roll-on solution which u can buy from pharmacy - use it thhe day b4 and on the day of gig.
2) Surgery - sympathectomy which means removing the nerves that supply the sweat glands - pretty safe but small chance of puncturing your lungs if u r obese. Works for sweaty palms NOT feet (if u play footsy and want that cleared too? forget it)
3) Electrophoresis - supposed to work and these devices are sold on the internet... but dun waste your money. Not a permanent cure and u have to ue them regularly. Unless u have lots of time to do it 45min/day every day....
4) Medication - yes, can help but dries your mouth, eyes, etc too. So not recommended.
5) The cloth in your pocket.
BTW, we sweat for 2 reasons,
A) Perspiration - heat, etc (Function of the sweat glands to cool body down)
B) Cold Sweat - fear, fright (eg. stage fright) - (Function of the nerves for fright & flight)