The IUS is a small device that is put into a woman’s uterus (womb) by a doctor or nurse. It is made from plastic and contains progestogen hormone. Therefore, it is called an intrauterine system (IUS) and not just an intrauterine device (IUD). An IUS works for five years before it needs replacing.

Mirena® is the only IUS available in the UK, although others will probably become available in the future.

It is more than 99% effective.

Side-effects are uncommon. Possible side-effects include: mood swings, reduced sex drive, fluid retention, increase in acne and breast discomfort.