My left wrist had been sweating at random times for a couple of years or so now. It is very counterproductive, especially since I write with my left hand and I usually end up getting sweat on the paper. (Not sure if this will help, but: I'm 15, 145 pounds, about 5'9 and I'm in good shape from exercise.)
When it first started happening it would only do it a little and I just didn't pay attention to it, but now it's gotten at least 5 times worse. When it started getting real bad I tried to come up with a remedy and went through a lot of self-treatments. I realized that my wrist wasn't just sweating, it was that my wrist was insanely hot. Whenever I would wipe away the sweat with a napkin, it would just come back about 30 seconds later. Even when i'm in a normal or cold room, my wrist will still sweat at times(which makes me even colder).
Some things I tried were: Putting ice on my wrist which cooled down my wrist, but as soon as I took the ice off of my wrist, it would begin to sweat again after about 30 seconds later. Another thing I did was putting Fast Orange hand cleaner on my wrist, which actually did work pretty nice, but wore off after about a half-hour. The Fast Orange not only stopped the sweating, but also cooled down my wrist A LOT. It actually kind of made my wrist a little cold (Probably just from the sweat.
Another thing that I have noticed is that when I keep a good flow of exercises everyday, my wrist won't sweat as much. I try to exercise everyday, but sometimes I can't.
Also, I've noticed that when I have to urinate and I hold it in instead of going to the bathroom while my wrist is sweating, sometimes once I've relieved myself my wrist will have stopped sweating. But that is only sometimes. And I'm almost positive that not using the bathroom when I have to is not what's causing the sweat.
I've researched it and some things I've read suggest I have focal hyperhidrosis. But I have researched focal hyperhidrosis too and usually those with it, have it symmetrically. And from what I've read on it is that they usually have it on their hands, feet, and armpits. But none of what i've read had pictured anyone with it on just one side of their body or on their wrist.
Thanks for your help.