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Intrauterine devices & systems (IUDs & IUSs)

An intrauterine device (IUD) is a plastic and copper device that's placed in your womb through the natural opening in your cervix at the top of your vagina. It works by stopping sperm reaching your egg and may also stop a fertilised egg implanting in your uterus. It doesn't contain any hormones.

An intrauterine system (IUS, Mirena or Jaydess) is a plastic IUD that also releases a small amount of the hormone progestogen into your womb. This thins the lining of your womb and thickens your cervical mucus, so that an egg can't be fertilised or implant into your womb and grow. It prevents some women from ovulating (releasing eggs).

Because an IUS thins your womb lining, most women using one have much lighter periods or no bleeding at all. This means it can also be used to control heavy periods.

An IUD can be inserted as emergency contraception up to five days after unprotected sex. This is the recommended option for women who weigh over 70 kg.

An IUD or IUS is effective for at least five years and you can get it taken out at any time. It's a suitable long-term contraception for most women.

A trained GP, practice nurse or gynaecologist fits an IUD or IUS in a simple procedure. See Inserting an IUD or IUS (Mirena or Jaydess) for details of how this is done.

A IUD can cause cramps, and heavier periods.

An IUS may give you irregular, or light periods.

Very rarely there can be a problem when the IUD or IUS is inserted. Also rarely, the device can fall out without you noticing.

You can check if the device is still present by feeling for the soft strings that sit in the top of your vagina.

See your GP, or Family Planning Clinic to find out if an IUD or IUS is right for you.

If you're 21 or younger, this visit may be free.

  HealthInfo recommends the following pages

On the next page: Inserting an IUD or IUS

Written by HealthInfo clinical advisers. Last reviewed February 2019.

Page reference: 54617

Review key: HICAS-53138