Intrauterine system

What is the intrauterine system (IUS)?

A small, flexible piece of soft plastic that fits inside the womb. It’s sometimes called a hormonal or contraceptive coil.

It’s easily inserted by a trained healthcare professional.

How does the IUS work?

The IUS releases a hormone progestogen into the womb which thickens the mucus at the entrance of the womb making it difficult for sperm to pass through and also thins the lining in your womb, making it difficult for an egg to implant there. It can stop ovulation (an egg being released) in some women.

How effective is the IUS?

It’s over 99% effective 1. Less than 1 in 500 people will become pregnant using the device.

Are there any side effects of the IUS?

Some people might experience side effects with the IUS, these can include:

  • Your periods may become much lighter, less frequent, irregular or stop altogether.
  • Occasionally the hormonal coil can cause temporary side effects which include spotty skin (acne), breast tenderness and mood swings. These tend to stop within a few months.

How long does the IUS last?

There are several types of IUS – Mirena, which provides protection from pregnancy up to 5 years and Levosert which is effective up to 6 years.

There are lower dose IUS options: Kyleena which is effective for 5 years and Jaydess which is effective for 3 years.

You can have the IUS removed at an earlier time should you want though.

Fitting, removing and changing the IUS

Speak to your GP or sexual health clinic who may offer you a preliminary consultation. You may be advised to screen for sexually transmitted infections (STIs).

Your appointment for fitting will last between 20 and 30 minutes. You’ll be given an internal examination to fit the device in the right place. It takes around 5 minutes to insert. It can be a little uncomfortable or painful so you may be given a local anaesthetic.

Once fitted, you’ll be shown how to check it’s still in place by your doctor or nurse.

You may have some pain and/or a little bleeding after getting your IUS fitted, this should settle within a few days but if it doesn’t, call your doctor or sexual health clinic. There’s a small risk you could get an infection within the first 3 weeks of having your IUS fitted. Getting tested for STIs before will help avoid this. There’s a small chance your IUS could be pushed out or displaced (move) and you’ll no longer be protected against pregnancy. Regularly checking it’s in place will help.

When you’re ready to have it removed this can be done by a trained healthcare professional. They can also put a new one in then, if you would like. Your fertility returns to normal once it is removed.

Things to consider when getting the IUS

  • A hormonal coil doesn’t prevent you from getting STIs so you may want to use condoms too.
  • The effectiveness of your IUS isn’t affected by other medications.
  • Your fertility returns to whatever is normal for you once it is removed.
  • In the first 6 months you may experience irregular bleeding and spotting. Bleeds or periods usually become lighter, less frequent and may stop altogether. There is no evidence to suggest this is harmful.
  • There is a 1 in 500 risk of the device perforating (making a hole in) the womb lining.
  • If the device fails and you become pregnant, the pregnancy may more likely be an ectopic pregnancy.

Difference between IUD and IUS

An IUD (copper coil) is non-hormonal whereas an IUS works by releasing hormones. An IUD could be better for you if you don’t get along with hormonal methods. The IUD can also be used if you need emergency contraception too.

Where can I get the IUS?

You can get the IUS for free at NHS sexual health clinics, contraception clinics and some young people’s services. Some GP surgeries may be able to fit it but not all can.

Other contraception options

If an IUS isn’t right for you there are other forms of long-acting reversible contraception available including the intrauterine device (IUD), the injection and the implant. After starting these methods you’re protected from pregnancy for months (injection) to years (implant/IUD).

If you’d prefer something a bit more flexible, that gives you the ability to manage your periods, you could choose from contraceptive pills, the contraceptive patch or the vaginal ring (NuvaRing). If you live in an eligible borough you can order these for free from SHL, Register or Login to find out more.

Reviewed by our clinical team: December 2020 (next review date: April 2022)

1. Source: NHS How effective is contraception at preventing pregnancy? - NHS (