The IUS works in the same was as an IUD, but it also releases a hormone very slowly in the woman’s body, providing additional protection by causing the cervical mucus to become thicker, blocking the sperm’s travel to the egg and for some women, stopping ovulation altogether. 

The IUS also provides protection for up to five years, but it is even more effective than the IUD (over 99%) and it often decreases blood loss and cramps, sometimes stopping menstruation (periods) altogether.  

It may also increase sexual pleasure by removing the fear of pregnancy.

It does not provide any protection against sexually transmitted infections (STIs).