Intrauterine system (IUS)

The intrauterine system (IUS) is:

  • 99% effective 

What is it?

IUS stands for intrauterine system. It is a small plastic device placed in the woman’s womb that releases the artificial progestogen hormone called levonorgestrel.

There are three different kinds of IUS or hormone coil available in Ireland: Mirena, Kyleena and Jaydess.

How does it work?

It works in several different ways. It:

  • stops the man’s sperm from reaching the woman’s egg
  • delays the egg getting to the womb
  • prevents the egg from implanting in the womb

Before you decide if you would like to try an IUS, it is important that you talk to a doctor. They will help you assess what contraceptive option is best for you.


  • It does not interrupt sex.
  • If you take medication, the hormone coils will NOT be affected as they work locally.
  • It works as soon as it is inserted and within one week. 
  • You can use the IUS even if you have never been pregnant or if you have delivered a baby by C section.
  • The IUS can be used by young women.
  • It can stay safely inside you for three years (Jaydess) to five years (Mirena & Kyleena).
  • It can be left inside you until after a menopause if you are 45 years old at the time it is fitted.
  • The Mirena coil is a common alternative to surgical correction of heavy periods in older women.
  • If you have menopause symptoms and are older you can use the Mirena coil as part of your hormone replacement treatment.
  • The coil may cause irregular bleeding for the first few months, but after that time you may have lighter and often no periods.


  • Inserting and removing an IUS must be done by a specially trained doctor.
  • It does not protect you against sexually transmitted infections.
  • It may be uncomfortable for you to have one inserted. This varies from woman to woman.
  • If you do not have a medical card, you will have to pay to have the coil inserted.