The IUS helps to reduce heavy periods and is also very good at preventing pregnancy. If 1,000 women use an IUS for five years, the chances are, only about seven will get pregnant. The IUS isn’t thought to be affected by other medicines and is safe to use if you’re breastfeeding. The IUS doesn’t protect you against sexually transmitted infections – for that you need to use a condom.
The two types of IUS available in the UK are the Mirena® and Jaydess®. Although both work as contraceptives, only Mirena® is approved to treat heavy periods. The Mirena® IUS can be placed in your womb for up to five years. Your GP will only usually recommend the IUS if you’re happy to have it for at least a year.
During each menstrual cycle, the lining of your womb (endometrium) thickens and gets ready for a fertilised egg to grow. If you don’t become pregnant, your endometrium breaks down and you have a period.
The IUS releases levonorgestrel very slowly into your womb. This hormone stops your endometrium from growing as much. This means your endometrium is thinner than usual, so there is less to shed during your period. Many women find their periods become shorter and lighter with the IUS, but it doesn’t work for everyone.
The IUS prevents pregnancy by making it difficult for a fertilised egg to grow in your womb. It also thickens the mucus made by your cervix (the neck of your womb), which makes it difficult for sperm to enter. The IUS may stop your ovaries from producing eggs (ovulation), but this doesn’t happen in all women.
Your GP or a health professional at a family planning clinic will look at your medical history. They’ll also consider any conditions that your close family members have when advising whether or not the IUS might be suitable for you.
The IUS might not be suitable if you have had certain medical conditions, which include:
You’ll usually have your IUS fitted within seven days of the start of your last period. If you’re sexually active and the IUS is fitted later than that, make sure you use another form of contraception for at least a week.
Your doctor or a specialist nurse will fit your IUS. The procedure can take up to 15 minutes. You might want to take over-the-counter painkillers around 30 minutes before you have your IUS fitted.
Your doctor or nurse will open your vagina using a speculum to make it easier to see your cervix. They will then pass a thin tube containing the closed IUS through your cervix into your womb. They will open up the IUS into a T-shape when it's in your womb, so that it stays in place.
The IUS has two soft threads that come through your cervix and sit at the top of your vagina. These are to make it easier for your doctor or nurse to remove your IUS at a later date. You can also use them to check your IUS is in place. The threads of the IUS are trimmed once it’s in place, so that they can be felt but not seen externally. After that, your doctor or nurse will remove the tube and speculum.
You may notice that your periods change. Most women find that their periods become lighter, less frequent or stop altogether. It may take up to six months for your periods to settle. During your period, it’s safe to use tampons if you want to.
Sometimes, women can develop an infection in the days after their IUS is fitted. Contact your GP or family planning clinic if you feel unwell, have a high temperature or a smelly discharge from your vagina. These are possible signs of an infection.
You’ll need to have your IUS checked about six weeks after it’s fitted. Your doctor or nurse will check its position and ask if you’re having any problems.
After your IUS is fitted, your doctor or nurse will explain how you can check that your IUS is in place. You can do this by feeling in the top of your vagina for the threads. Be careful not to pull the threads. Check your IUS a few times in the first month and then monthly from then on.
It’s unlikely that your IUS will come out of your womb, but contact your GP or family planning clinic if you:
- feel part of the IUS in your vagina
- can't feel the threads of the IUS
- have severe pain or bleeding
If you think your IUS has moved, use another contraceptive until you’ve seen your GP or family planning clinic.
Your IUS will usually be removed within a couple of days of your period starting. If it’s removed at another time during your menstrual cycle and you don’t want to get pregnant, use another contraceptive for at least a week before your appointment. You’ll need to consider what contraception you want to use after your IUS is removed.
If you want to continue using an IUS, you can usually have a new one fitted at the same appointment. If you do this, you’re protected from pregnancy and won’t need to use another contraceptive.
To remove the IUS, your doctor or nurse will examine you and then remove the IUS by gently pulling the threads. Don’t try to remove the IUS yourself.
Side-effects are the unwanted but mostly temporary effects you may get after having a procedure. Side-effects of having an IUS inserted are listed below.
- You may feel faint while the IUS is being inserted, although this is unusual.
- You may have some pain, discomfort or bleeding when the IUS is fitted or removed, and a feeling similar to period pain afterwards. If you need pain relief, you can take over-the-counter painkillers such as paracetamol or ibuprofen.
You might have some side-effects during the first few months of having the IUS. These include light bleeding (spotting), tender breasts, acne, headaches and mood changes, but these should settle with time. See your GP if any of these side-effects are affecting your day-to-day life.
Complications are when problems occur during or after a procedure. Possible complications of the IUS are listed below.
- You may develop cysts on your ovaries. These are usually harmless and disappear after a few months without treatment.
- There’s a small risk you’ll develop pelvic inflammatory disease. This is usually caused by an infection and clears up with antibiotics.
- The IUS could damage (perforate) your womb or cervix. This is uncommon, and happens in about one in every 1,000 women having an IUS fitted. If this happens, the device will need to be removed immediately, and you may need surgery to repair the damage.
- There is a chance that your IUS will come out. Over five years, this happens to about one in 20 women.
- It’s possible for the threads to become lost. They may have broken off, or have moved inside your womb. If this happens, your doctor or nurse will need to double check that your IUS is still in place. You may need an ultrasound or X-ray for this.
If you can’t feel the threads, use another form of contraception and contact your doctor.
If you have heavy periods, the IUS is usually the first option to help, provided you don’t want to get pregnant. It’s not your only option though. Alternatives include:
- other types of hormone contraception
- a drug called tranexamic acid
- some types of painkiller
If other treatments haven’t worked or aren’t suitable for you, surgery might be an option. Some women find that endometrial ablation works well for them. This procedure destroys the tissue in your womb (your endometrium) that’s a source of heavy periods.
Another option is to have your womb removed (a hysterectomy). This is major surgery and comes with risks and complications, so it may be worth exploring other options first. Your GP can explain which options may be suitable for you and can refer you to a specialist if needed. You can find out more about other treatment options on our page about heavy periods.
If you become pregnant
It's very unlikely that you’ll become pregnant if you have an IUS. It’s very important to see your GP as soon as possible if you think you may be pregnant. They will recommend that your IUS is removed.
They will also check that the fertilised egg is in the right place. This is because there is a small risk that it may be growing outside your womb, most often in one of your fallopian tubes. This is called an ectopic pregnancy. If this happens, you may need urgent treatment, as an ectopic pregnancy can be dangerous.
If your pregnancy is in your womb as normal, your doctor will advise you to have your IUS removed immediately. This is to reduce your risk of having a miscarriage or premature labour. However, removing the IUS also carries a risk of miscarriage. It’s important to discuss this fully with your doctor so you understand the risks.
Yes, you may be able to have an IUS fitted after six weeks.
An IUS can be fitted from six weeks onwards after you give birth. If you’re bleeding from your vagina or have pain, your doctor will need to find the cause before you have an IUS fitted. An IUS may not be suitable for you if you have:
- a history of fibroids
- liver disease
- breast, cervical or endometrial cancer
- pelvic inflammatory disease
- bleeding from your vagina for no known reason
You’ll need to use another method of contraception from three weeks after you give birth until you have an IUS fitted.
It’s safe for you to use an IUS if you’re breastfeeding. It won't affect your ability to breastfeed or reduce your breast milk supply.
If you aren't sure about whether an IUS would be suitable for you, speak to your GP.
Heavy periods are ones where you have a lot of bleeding. They can affect you both physically and emotionally. As well as affecting your physical health, you may find that you avoid going out, running daily errands or socialising.
If you have heavy periods (menorrhagia), you’ll typically lose more than 80ml of blood (a third of a cup) during each period. As it’s not easy to tell how much you’re bleeding, doctors usually diagnose heavy periods using other signs.
Signs that your periods could be heavy are:
- having to use a lot of sanitary protection (eg using both a tampon and towel)
- having large blood clots in your period
- bleeding through to your clothes or bedding (sometimes called 'flooding')
- having painful periods
- not being able to do your usual hobbies or social activities because of your periods
- having mood changes
Heavy periods disrupt not only your life, but they can also put you at risk of developing anaemia due to a lack of iron. This means your body can’t produce as many red blood cells as are needed, which are important for carrying oxygen around your body. Around two in three women with heavy periods have anaemia linked to low iron. This can make you feel tired and breathless, and you may have palpitations (heartbeats that suddenly become more noticeable).
If you think your periods are unusually heavy, speak to your GP for advice.
Your partner won’t be able to feel your IUS during sex, but they might be able to feel the threads. However, this is unlikely.
If your IUS is in the correct position, your partner won’t be able to feel it. There are two thin threads at the top of your vagina that they may feel during sex, although this is unlikely.
If you can feel the IUS itself (rather than just the threads), see your doctor right away, as it will need to be removed. If your partner can feel the threads during sex, talk to your GP or nurse. They may be able to trim the threads to make them slightly shorter if it’s a concern to you.
- Family Planning Association (FPA)
0845 122 8687 (Northern Ireland only)
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- Mirena®: summary of product characteristics. The electronic Medicines Compendium (eMC). www.medicines.org.uk, published 1 July 2015
- Map of Medicine. Dysmenorrhoea. International View. London: Map of Medicine; 2013 (Issue 1)
- Map of Medicine. Abnormal vaginal bleeding. International View. London: Map of Medicine; 2013 (Issue 4)
- Gilson G. Clarifying hormone terminology. Can Fam Physician. 2007; 53(1):29–30
- Your guide to the IUS. Family Planning Association. www.fpa.org.uk, published June 2014
- Jaydess®: summary of product characteristics. The electronic Medicines Compendium (eMC). www.medicines.org.uk, published 1 July 2015
- Simon C, Everitt H, van Dorp F, Burkes M. Oxford handbook of general practice. 4th ed. Oxford: Oxford University Press, 2014
- Intrauterine contraceptives (IUCD and IUS). PatientPlus. www.patient.info/patientplus, published April 2014
- Levonorgestrel Intrauterine. Medscape. reference.medscape.com, published April 2015
- Ectopic pregnancy. NICE Clinical Knowledge Summaries. www.cks.nice.org.uk, published July 2013
- Menorrhagia. Medscape. www.emedicine.medscape.com, published September 2014
- Menorrhagia. PatientPlus. www.patient.info/patientplus, published March 2014
- Ectopic pregnancy. NICE Clinical Knowledge Summaries www.cks.nice.org.uk, published July 2013
- Faúndes D, Perdigão A, Faúndes A, et al. T-shaped IUDs accommodate in their position during the first 3 months after insertion. Contraception. 2000; 62(4):165–68
- Family Planning Association (FPA)
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