IUS (intrauterine system)

The IUS works in three ways to prevent the egg being fertilised by sperm. The IUS interrupts this process by:

• Thickening the mucus around the cervix, which makes it harder for sperm to get through and reach an egg
• Makes the lining of the womb thinner so that a fertilised egg cannot implant
• In some women it can also stop ovulation (when ovaries release an egg), although most women continue to ovulate.

The IUS needs to be fitted by a doctor or nurse who has been specially trained. It is available free from a range of services including contraceptive clinics, your GP and Brook. Find your nearest using our find a service tool.

Contraception and sexual health services such as Brook are free and confidential, including for people under the age of 16. Health professionals work to strict guidelines and won’t tell anyone else about your visit unless they believe you’re at serious risk of immediate harm. Find out more about Brook’s confidentiality policy.

An appointment will typically include:

• A few questions about your medical and family history, to work out what method would suit you best.
• You will need to have an internal examination – a doctor or nurse will look inside your vagina to check the position and size of your uterus before the IUS can be fitted
• They will also check for any signs of infection, sometimes you may also be given antibiotics.

Some services may be able to fit it at the same appointment, or you may need a second appointment.

Fitting the IUS (shouldn’t take longer than 5 minutes):

1. You’ll be asked to lay on the bed
2. Remove the lower half of your clothing (e.g. trousers/skirt and underwear)
3. Open your legs and bend your knees so the doctor or nurse can use a speculum to slightly widen your vagina to help insert the IUS into your uterus.

The doctor or nurse may discuss painkiller tablets and/or using local anaesthetic to make the fitting more comfortable.

Currently there are four brands of IUS – Mirena, Kyleena, Levosert and Jaydess. Some brands work for five, four or three years.

You may get period-type pain and possibly some light bleeding for a few days afterwards.

The IUS has two threads which hang through the opening at the entrance of your uterus (cervix). You should check the threads a few times during the first month and then at least once a month.

It is very unlikely that the IUS will come out but if you are worried or cannot feel the threads you should see a doctor or nurse straight away. You will then only need to go back when the IUS needs to be replaced (3 to 5 years depending on the type of IUS).

The IUS can be fitted any time in your cycle if it is certain that you are not pregnant. If fitted in the first seven days of your menstrual cycle you will be immediately protected against pregnancy. If it is fitted at any other time, you will need to use an additional method of contraception (such as condoms) for the first seven days.

If you have a short menstrual cycle, where your period normally comes every 23 days or less, you will have to start the IUS in the first six days (because you might ovulate early in your menstrual cycle).

The IUS must be removed by a trained doctor or nurse. The procedure should be less painful and quicker than when the IUS was inserted. If you are not going to have another IUS you’ll need to use additional contraception, such as condoms, for the seven days before the IUS is taken out if you do not want to become pregnant.

Your fertility should return to normal as soon as the IUS is removed.