glaucoma
"I only had side effects for the first 2 weeks. The most annoying side effect was the tingling in my feet and knees. Luckily, my hand were fine. I also had to go pee at least 20 times a day and each time I would pee a hell lot of water. This was mostly disturbing when I was at work and had to get up every 30 minutes to go to the bathroom. My head also felt pretty light and I fell asleep easily during the day. Other than that, it isn't AS bad as the other comments say. I was pretty scared after reading a couple of those. 
In all, this medicine does require some getting used to. Luckily for me, it passed after two weeks or so. Except for the tingling in my feet. But I got used to it."