Deb - Actually Mirena would be more than suited to those who can't take the pill - the hormones in a Mirena are released straight into the uterus in small doses (rather than larger doses that course throughout your body).
It also doesn't contain estrogen, which is where most of the side effects come from.
Maybe it was unsuitable for your particular situation (there are always exceptions) but it is definitely an option for most people.
ETA - the website has really good information -
link
Edited by nikkiwhyte