Common side effects of the hormonal IUD include irregular bleeding, heavier bleeding and spotting, especially within the first six months of use. In addition, some women may stop having menstrual cycles altogether in about two years. Other possible side effects are related to the hormone secreted by the IUD, progestin. These can include headache, nausea and breast tenderness. Some women may develop cysts on their ovaries. While these tend to go away without treatment in a month or two, they can cause some pain.
There are also some serious, albeit rare, risks associated with IUDs. In about one in every 1,000 IUD insertions, for example, the IUD pierces the uterine wall, and there is also a chance that the IUD will slide out of the uterus and into the vagina. Pelvic inflammatory disease, an infection of the uterus and fallopian tubes, is also a risk. And if a woman does become pregnant while using an IUD, there is a chance the pregnancy could be ectopic, meaning it occurs outside the womb. This is fatal to the fetus, and potentially life threatening to the mother.