Intrauterine system (IUS)

The intrauterine system (IUS) is:

  • Over 99% effective.

What is it?

It is a small T shaped plastic device that is put into the womb. 

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

It can only be inserted and removed by a specially trained doctor.

How does it work?

The IUS contains progestogen, an artificial form of the hormone progesterone.

It works by:

  • stopping the sperm from reaching the egg
  • thinning the lining of the womb to help prevent a fertilised egg from settling (implanting) in the womb

It is important that you talk to a doctor who will assess what contraceptive option is best for you.


  • It does not interrupt sex.
  • It protects you for 3-6 years depending on the device. But you can get it taken out sooner.
  • If inserted after the age of 45 it may stay in place until the menopause.
  • Periods often become lighter, shorter and less painful. 


  • You may have irregular bleeding or spotting in the first 6 months.
  • It does not protect you against sexually transmitted infections.