I started Yaz 18 mos ago to regulate mentrual cycle that was getting out of control (when I had my period for 21-24 days out of 30 for 3 mos I gave in to dr's suggestion that I use low dose birth control). I have experienced an increase in back pain, bruising, and total body achiness. Also get occasional pins/needles or feeling of numbness in my left arm. I had not connected any of this to the Yaz until reading several posts on this site, most from young women. A recent mammogram showed several new cycsts on my left breast which will require f/u in 6 mos. Guess what I'd like is to hear from anyone else who has been prescribed YAZ for premenopausal issues and what type of side effects, if any, you have experienced? At this moment, though it definitely aided in controlling the menstrual cycle, I'm ready to just stop taking it. One thing that I noticed almost from the start was that I was passing heavy clots when I got my period and my dr said that was not something to worry about. Posts here suggest otherwise.