I am a woman and I really do perspire excessively in my armpits to the point where I plan my clothing to hide perspiration. It is embarassing! It diminished considerably when I was on acne medication (Acutane) for 6 months. I am tall and thin and measure 5ft 9" and weigh 130lb. Could it be hyperactive thyroid? It is worse on certain days of my cycle when there are big changes in hormones levels.