Copper
"I've had my Paragard for over a year.  I chose Paragard because I can't use hormonal birth control.  I've never had children or been pregnant.  The insertion was painful, but not that bad.  I'd rank it as a 5/10 on the pain scale.  The cramps following insertion were awful, I'd rank them as a 7/10.  Those lasted about 24 hours.  The entire first month I had almost constant cramps.  Over the counter pain killers wouldn't even TOUCH the pain.  The first period after insertion was really hard.  The cramps were so bad.  After the first period ended things were almost normal.  I still get much more painful crampy periods, but that is diminishing.  My cervix is still sensitive and can hurt during sex. Discharge during ovulation is normal. Increased sex drive."