93% with typical use
99% if used perfectly.
$45 each month, however, this method may be free or at a reduced charge based on your household income!
Do not have to take a pill everyday (leave it in for 3 weeks)
Does not require a doctor to put it in
Reduces risk of ovarian cysts and breast tumors
Reduces risk of "female" cancers
Eases PMS symptoms
Regulates menstrual cycle
May cause breast tenderness, headaches, or nausea
May cause irritation, discharge, or vagina infections
Antibiotic reduce the effectiveness