Hormonal intrauterine devices (IUDs) are long-acting reversible contraceptives and are considered one of the most effective forms of birth control. They may cause minor side effects. Once your body adjusts to the change in your uterus the cramping will slowly disappear. Hormonal IUD side effects aren't hazardous, but there are some risks associated with IUD use. If you're experiencing any discomfort, speak with your doctor about it.