Intrauterine System (IUS or hormonal coil)

(Mirena / Levosert / Kyleena / Jaydess)

The hormonal coil (IUS) provides long acting, reversible and reliable contraception.

What is the IUS?

The IUS is a small T shaped plastic device which slowly releases a low dose of the hormone progestogen into the lining of the womb.

How does the IUS work?

It makes the lining of your womb thin so it is less likely to accept a fertilised egg. It also thickens the mucus in your cervix which will stop sperm reaching your egg. In some women it also stops ovulation.

How effective is the IUS?

The failure rates for IUS are less than 1% per year.

Advantages of the IUS

  • It is extremely effective contraception
  • It works for 3-5 years (depending on which device is fitted)
  • Your periods will become much lighter and shorter and they may stop after first year
  • It is not affected by other medicines
  • It doesn’t interfere with sex.

Disadvantages of the IUS

  • You will need to have an internal vaginal examination to have it fitted
  • Sometimes you can get irregular light bleeding in the first few months; this usually settles by 6 months
  • Some women develop small cysts on their ovaries; these usually do not need any treatment but some women may have some pelvic pain
  • It does not protect you from sexually transmitted infections (STls) so you may need to use condoms as well.

Are there any risks?

If you are at risk of STls then you may be more at risk of getting a pelvic infection - this is more likely in the first 3-6 weeks after the IUS is fitted. To try to prevent this happening we offer a test for Chlamydia and Gonorrhoea to all women prior to the fitting.

Occasionally, a women’s body might push the IUS out of her womb (expulsion); this is more likely to happen in the first few months after fitting.

On rare occasions the IUS may go through (perforate) your womb or cervix. Sometimes this causes pain but it may cause no symptoms at all. If this happens then the IUS may have to be removed by surgery.

If you do become pregnant while you are using an IUS there is a small risk that the pregnancy may be an ectopic pregnancy. However, the risk of an ectopic pregnancy is less in women using an IUS than in women using no contraception.

How do I get an IUS?

Ask the nurse or doctor in clinic and they will talk to you about the advantages and disadvantages of having an IUS and they will also recommend an STI screen.

How is an IUS fitted?

An IUS is fitted inside the uterus (womb). The nurse or doctor will examine you internally to check the size of your womb before they fit the IUS. The fitting usually takes between 15 to 20 minutes.

On the day of your fitting appointment please have something to eat and one hour before take a dose of a mild painkiller (paracetamol or ibuprofen).

After the IUS fitting

After the fitting you may get some period type pain and some light bleeding for a few days. It is a good idea to take a mild painkiller (paracetamol or ibuprofen) to help with this.

If you have any problems or feel unwell (with pain or discharge from your vagina) then please seek medical attention.

How do I check my IUS?

The IUS has two threads attached to it, which hang through the neck of the womb (cervix) into the vagina. You can check that your IUS is in the right position by putting your finger in the vagina to feel the threads from the IUS coming out of the cervix.

You should not be able to feel the IUS itself. It is advisable to check your IUS threads once a month. If you are unable to feel your threads, please attend the clinic.

I’ve just had a baby. Can I use an IUS?

An IUS can be fitted within 48 hours of delivery OR from 4 weeks after vaginal or caesarean delivery. The IUS is safe to use whilst breastfeeding.

Will an IUS affect my periods?

Yes, your periods will become lighter and shorter and may stop altogether. In the first few months you may experience irregular bleeding but it should be lighter than your usual periods. It is safe to use tampons.

Having an IUS removed

An IUS can be removed at any time by a trained nurse or doctor. If you do not want to become pregnant you need to start using an alternative method of contraception 7 days before you have your IUS removed. Ask the clinic nurse or doctor for advice about this.

Do I need to have my IUS checked by a nurse or doctor?

No. if you have no problems, and you can feel your IUS threads, then you do not need to have regular IUS checks.

If you have any of the following problems, then please seek medical attention:

  • You cannot feel your IUS threads especially if you usually feel them every month
  • You develop unusual lower abdominal pain
  • You develop an unusual vaginal discharge
  • You feel unwell with a high temperature in the first few weeks after fitting.

Emergency Contraception

An IUS cannot not be used as emergency contraception.

Does the IUS protect me from sexually transmitted infections (STls)?

No, the IUS only protects you from pregnancy. If you want to avoid STls including chlamydia, gonorrhoea and HIV, it is important to use condoms as well.

Condoms are available free from clinic.

This information should not replace the information that accompanies your IUS which will be given to you after the fitting.

Sometimes there may be a trainee doctor or nurse in clinic, fitting your IUS. All trainees are closely supervised by experienced doctors.

Need further help/advice?

Please make an appointment for one of our clinics.

Did this information help you?

  • Page last reviewed: 23 January 2023
  • Next review due: 23 January 2024