birth control
"I've been taking Trivora for a couple of years now. It's great except I have an EXTREMELY noticeable decrease in sex drive. There is a huge difference between the three weeks I'm taking active pills and the one week that I'm not. Then again... Maybe that's just me. 

Kind of a catch 22, isn't it? If I wanted my normal sex drive back, I'd have to go off of the pill."