Hi Wingnut,
Here is a link to the mirena coil. Scroll down to it, and read the product monograph aswell as the patient information.
This information will not be relayed to you by the doctor and it is important you get this information before you go ahead with it.
I gained 2 stone in weight, looked permanently pregnant, totally got put off sex as I had no libido, got bad acne and my hair became very thin and begun to fall out. My periods became very heavy, where as the patient leaflet states it stops your periods..... maybe.
I got it removed and it has taken over a year to recover from the experience.
Some people however do get on with it.
http://www.bayerhealth.com/BayerHC/display.cfm ?Object_ID=272&Article_ID=56&expandMenu_ID=53& prevSubItem=5_52