fortunately there is really nothing specific you have to avoid. the mirena has two modes of contraceptive protection. the first is the mechanical presence of the iud inside the uterine cavity. this has been the mechanism of action of all the earlier iuds which were just inert plastic. mirena also has the the slow infusion of synthetic progesterone into the area of the uterine lining. this makes the lining very thinned out (hence lighter or absent menstrual periods). most importantly would be to check your strings at the end of each period (or calendar month) and to stay within a monogamous sexual relationship. if you do have multiple partners then use of a condom would be suggested to avoid infections like gonorrhea or chlamydia. .
is there anything that can interfere with the effectiveness of the mirena iud?