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IUS (intrauterine system)

A woman can get pregnant if a man’s sperm reaches one of her eggs (ova). Contraception tries to stop this happening by keeping the egg and sperm apart or by stopping egg production. One method of contraception is the IUS, or intrauterine system (sometimes called the hormonal coil).

At a glance: facts about the IUS

How the IUS works

Who can use the IUS

Advantages and disadvantages of the IUS

Risks of the IUS

Where to get the IUS

An IUS is a small, T-shaped plastic device that is inserted into your womb (uterus) by a specially trained doctor or nurse.

The IUS releases a progestogen hormone into the womb. This thickens the mucus from your cervix, making it difficult for sperm to move through and reach an egg. It also thins the womb lining so that it's less likely to accept a fertilised egg. It may also stop ovulation (the release of an egg) in some women.

The IUS is a long-acting reversible contraceptive (LARC) method. It works for five years or three years, depending on the type, so you don't have to think about contraception every day or each time you have sex. Two brands of IUS are used in the UK – Mirena and Jaydess. 

You can use an IUS whether or not you've had children.

At a glance: facts about the IUS

  • It's more than 99% effective.Less than one in every 100 women who use Mirena will get pregnant in five years, and less than one in 100 who use Jaydess will get pregnant in three years.

  • It can be taken out at any time by a specially trained doctor or nurse and your fertility quickly returns to normal.

  • The IUS can make your periods lighter, shorter or stop altogether, so it may help women who have heavy periods or painful periods. Jaydess is less likely than Mirena to make your periods stop altogether.

  • It can be used by women who can't use combined contraception (such as the combined pill) – for example, those who have migraines.

  • Once the IUS is in place, you don't have to think about contraception every day or each time you have sex.

  • Some women may experience mood swings, skin problems or breast tenderness.  

  • There's a small risk of getting an infection after it's inserted.

  • It can be uncomfortable when the IUS is put in, although painkillers can help with this.

  • The IUS can be fitted at any time during your monthly menstrual cycle, as long as you're definitely not pregnant. Ideally, it should be fitted within seven days of the start of your period, because this will protect against pregnancy straight away. You should use condoms for seven days if the IUS is fitted at any other time.

  • The IUS does not protect against sexually transmitted infections (STIs). By using condoms as well as the IUS, you'll help to protect yourself against STIs.

How the IUS works

How it prevents pregnancy

Having an IUS fitted

How to tell whether an IUS is still in place

Removing an IUS

How it prevents pregnancy

The IUD is similar to the IUS (intrauterine system) but works in a different way. Instead of releasing the hormone progestogen like the IUS, the IUD releases copper. Copper changes the make-up of the fluids in the womb and fallopian tubes, stopping sperm surviving there. IUDs may also stop fertilised eggs from implanting in the womb.

There are types and sizes of IUD to suit different women. IUDs need to be fitted by a trained doctor or nurse at your GP surgery, local contraception clinic or sexual health clinic.

An IUD can stay in the womb for five to 10 years, depending on the type. If you're 40 or over when you have an IUD fitted, it can be left in until you reach the menopause or until you no longer need contraception.

Having an IUD fitted

An IUD can be fitted at any time during your menstrual cycle, as long as you are not pregnant. You'll be protected against pregnancy straight away.

Before you have an IUD fitted, you will have an internal examination to find out the size and position of your womb. This is to make sure that the IUD can be put in the correct place.

You can get contraception at:

  • most GP surgeries

  • community contraception clinics

  • some GUM clinics

  • sexual health clinics

  • some young people's services

Find a clinic near you

You may also be tested for infections, such as STIs. It's best to do this before an IUD is fitted so that you can have treatment (if you need it) before the IUD is put in. Sometimes, you may be given antibiotics at the same time as the IUD is fitted.

It takes about 15 to 20 minutes to insert an IUD. The vagina is held open, like it is during a cervical screening (smear) test, and the IUD is inserted through the cervix and into the womb.

The fitting process can be uncomfortable and sometimes painful. You may get cramps afterwards. You can ask for a local anaesthetic or painkillers before having the IUD fitted. An anaesthetic injection itself can be painful, so many women have the procedure without.

You may get pain and bleeding for a few days after having an IUD fitted. Discuss this with your GP or nurse beforehand.  

The IUD needs to be checked by a doctor after three to six weeks. Speak to your doctor or nurse if you have any problems before or after this first check or if you want the IUD removed.

Speak to your doctor or nurse if you or your partner are at risk of getting an STI. This is because STIs can lead to an infection in the pelvis.

See your GP or go back to the clinic where your IUD was fitted as soon as you can if you:

  • have pain in your lower abdomen

  • have a high temperature

  • have a smelly discharge

These may mean you have an infection.

How to tell whether an IUD is still in place

An IUD has two thin threads that hang down a little way from your womb into the top of your vagina. The doctor or nurse who fits your IUD will teach you how to feel for these threads and check that it is still in place.

Check your IUD is in place a few times in the first month, and then after each period or at regular intervals. 

It's very unlikely that your IUD will come out, but if you can't feel the threads, or if you think the IUD has moved, you may not be fully protected against getting pregnant. See your doctor or nurse straight away and use an extra method of contraception, such as condoms, until your IUD has been checked. If you've had sex recently, you may need to use emergency contraception.

Your partner shouldn't be able to feel your IUD during sex. If he can feel the threads, get your doctor or nurse to check that your IUD is in place. They may be able to cut the threads to a shorter length. If you feel any pain during sex, go for a check-up.

Removing an IUD

An IUD can be removed at any time by a trained doctor or nurse.

If you're not going to have another IUD put in and you don't want to get pregnant, use another method (such as condoms) for seven daysbefore you have the IUD removed. This is to stop sperm getting into your body. Sperm can live for up to seven days in the body and could make you pregnant once the IUD is removed.

As soon as an IUD is taken out, your normal fertility should return. 

Who can use an IUD

Most women can use an IUD. This includes women who have never been pregnant and those who are HIV positive. Your doctor or nurse will ask about your medical history to check if an IUD is the most suitable form of contraception for you.

You should not use an IUD if you have:

  • an untreated STI or a pelvic infection 

  • problems with your womb or cervix 

  • any unexplained bleeding from your vagina – for example, between periods or after sex

Women who have had an ectopic pregnancy or recent abortion, or who have an artificial heart valve, must consult their GP or clinician before having an IUD fitted.

You should not be fitted with an IUD if there's a chance that you are already pregnant or if you or your partner are at risk of catching STIs. If you or your partner are unsure, go to your GP or a sexual health clinic to be tested.

Using an IUD after giving birth

An IUD can usually be fitted four to six weeks after giving birth (vaginal or caesarean). You'll need to use alternative contraception from three weeks (21 days) after the birth until the IUD is fitted. In some cases, an IUD can be fitted within 48 hours of giving birth. An IUD is safe to use when you're breastfeeding and it won't affect your milk supply.

Using an IUD after a miscarriage or abortion

An IUD can be fitted straight away or within 48 hours after an abortionor miscarriage by an experienced doctor or nurse, as long as you were pregnant for less than 24 weeks. If you were pregnant for more than 24 weeks, you may have to wait a few weeks before having an IUD fitted. 

Advantages and disadvantages of the IUD

Although an IUD is an effective method of contraception, there are some things to consider before having one fitted.

Advantages of the IUD

  • Most women can use an IUD, including women who have never been pregnant.

  • Once an IUD is fitted, it works straight away and lasts for up to 10 years or until it's removed.

  • It doesn't interrupt sex.

  • It can be used if you're breastfeeding.

  • Your normal fertility returns as soon as the IUD is taken out

  • It's not affected by other medicines.

There's no evidence that having an IUD fitted will increase the risk ofcancer of the cervixendometrial cancer (cancer of the lining of the womb) or ovarian cancer. Some women experience changes in mood and libido, but these changes are very small. There is no evidence that the IUD affects weight.

Disadvantages of the IUD

  • Your periods may become heavier, longer or more painful, though this may improve after a few months. 

  • An IUD doesn't protect against STIs, so you may have to use condoms as well. If you get an STI while you have an IUD, it could lead to a pelvic infection if not treated.

  • The most common reasons that women stop using an IUD are vaginal bleeding and pain.

Risks of the IUD

Complications after having an IUD fitted are rare. Most will appear within the first year after fitting.

Damage to the womb

In fewer than one in 1,000 cases, an IUD can perforate (make a hole in) the womb or neck of the womb (cervix) when it's put in. This can cause pain in the lower abdomen, but doesn't usually cause any other symptoms. If the doctor or nurse fitting your IUD is experienced, the risk of this is very low.

If perforation occurs, you may need surgery to remove the IUD. Contact your GP straight away if you feel a lot of pain after having an IUD fitted as perforations should be treated immediately.

Pelvic infections

Pelvic infections can occur in the first 20 days after the IUD is fitted. The risk of infection is very small. Fewer than one in 100 women who are at low risk of STIs will get a pelvic infection.

Rejection

Occasionally, the IUD is rejected (expelled) by the womb or can move (this is called displacement). This is more likely to happen soon after it has been fitted, although this is uncommon. Your doctor or nurse will teach you how to check that your IUD is in place.

Ectopic pregnancy

If the IUD fails and you become pregnant, your IUD should be removed as soon as possible if you're going to continue with the pregnancy. There's a small increased risk of ectopic pregnancy if a woman becomes pregnant while using an IUD.

Where to get an IUD

Most types of contraception are available free in the UK. Contraception is free to all women. Places where you can get contraception include:

  • most GP surgeries – talk to your GP or practice nurse

  • community contraception clinics

  • some genitourinary medicine (GUM) clinics

  • sexual health clinics – these offer contraceptive and STI testing services

  • some young people’s services (call the sexual health line on 0300 123 7123 for details)

Find your nearest sexual health clinic by searching your postcode or town.

If you're under 16 and want contraception, the doctor, nurse or pharmacists won't tell your parents or carer, as long as they believe you fully understand the information you're given, and your decisions.

Doctors and nurses work under strict guidelines when dealing with people under 16. They'll encourage you to consider telling your parents, but they won't make you. The only time that a professional might want to tell someone else is if they believe you're at risk of harm, such as abuse. The risk would need to be serious, and they would usually discuss this with you first.  

IUS

IUS