An IUS (intrauternine system) is a small, T-shaped plastic device that is inserted into your womb (uterus) by a specially trained doctor or nurse. The IUS is a long-acting reversible contraceptive (LARC) method. 

What are the benefits of using an IUS?

  • It's more than 99 per cent effective.
  • It works for five years (Mirena).
  • It's one of the most effective forms of contraception.
  • It doesn't interrupt sex.
  • It can be taken out at any time by a specially trained doctor or nurse.
  • It can make your periods lighter, shorter or stop altogether.
  • It can be used by women who can't use combined contraception (such as the combined pill).
  • You don't have to think about contraception every day or each time you have sex.
  • It can be used safely if you're breastfeeding.
  • It's not affected by other medicines.
  • It may be a good option if you can't take the hormone oestrogen.

Things to consider

  • It does not protect against sexually transmitted infections.
  • Some women may experience mood swings, skin problems or breast tenderness.
  • There's a small risk of getting an infection after it is inserted.
  • It can be uncomfortable when put in. Painkillers can help with this.
  • It can be fitted at any time during your monthly menstrual cycle, as long as you're definitely not pregnant.
  • Periods may become lighter and more irregular or, in some cases, stop completely.
  • Irregular bleeding and spotting are common in the first six months after having an IUS fitted.
  • An uncommon side effect of the IUS is the appearance of small fluid-filled cysts on the ovaries.
  • Most women who stop using an IUS do so because of vaginal bleeding and pain.

Where can I get more information?

The Family Planning Association provides a range of helpful information.

My contraception tool

The FPA has developed an interactive tool that can help you find out which methods of contraception may be best for you.

The tool asks questions about your health, lifestyle and contraceptive preferences. All your answers are completely confidential and can't be linked back to you. The tool is available on their website.

Find out more