abnormal uterine bleeding
"I had no trouble the first month, but had a very heavy period at the end of it and then had breakthrough bleeding all month (varying in quantity) for the second month.  I thought I'd be all bled out after that and have a light period, but it was heavy again.  That was enough for me, and I switched to Ortho Tri-Cyclin Lo (which is what ended up working).  No side effects other than the breakthrough bleeding, but that was enough."