Intra-uterine system (IUS)

This page is for women who are considering having the levonorgestrel-releasing intra-uterine system (IUS) for heavy periods, or who would like information about it.
The IUS is a contraceptive device that’s placed in the womb (uterus). It can also help women who suffer from very heavy periods (menorrhagia).

About the IUS

The IUS is a small, T-shaped plastic frame that’s fitted inside your womb. The stem of the ‘T’ contains a hormone called levonorgestrel. Levonorgestrel is similar to the natural hormone progesterone that’s produced by your ovaries each month. Progesterone is an important part of ovulation as it stimulates your womb to shed its lining, causing a period.
The IUS is an effective hormonal contraceptive. Over five years,fewer than one in 100 women who use the IUS will get pregnant.
The type of IUS available in the UK is called Mirena®. This can be placed in your womb for up to five years. However, your GP will only recommend the IUS if you’re happy to have it fitted for at least a year.

How does the IUS work?

If you have very heavy periods, they can disrupt your lifestyle and increase your risk of developing anemia. Anemia is a condition where you have too few red blood cells or not enough hemoglobin in your blood. Around two-thirds of women with heavy periods have iron-deficiency anemia. Your GP may recommend the IUS to help manage your heavy periods. The IUS helps to reduce your symptoms by reducing the lining of your womb (endometrium). During each menstrual cycle, the lining of your womb thickens and gets ready for an embryo to implant if one of your eggs is fertilised. If you don’t become pregnant, the womb lining breaks down and you have a period. A period is your body’s natural way of removing the lining of your womb.
The IUS releases levonorgestrel very slowly into the womb. This hormone stops the lining of your womb thickening each month, making your periods shorter and lighter.
The IUS works as a contraceptive by making it difficult for an embryo to implant in your womb. It can also thicken the mucus that your cervix (the neck of your womb) produces, which can help to prevent sperm from entering your womb.
In some cases, the IUS can also stop your ovaries producing eggs. However, this is temporary and your ovaries will start to produce eggs again once your IUS is removed.

Is the IUS suitable for all women?

Your family history and medical history will help determine whether or not the IUS is suitable for you.

For example, the IUS might not be suitable if you have had fibroids (non-cancerous growths of the womb), liver disease, breast or endometrial cancer, pelvic inflammatory disease or bleeding from your vagina with no known cause (for example between periods or after sex).

How is an IUS fitted?

An IUS can be fitted by your GP, a gynaecologist (a doctor who specialises in women’s reproductive health) or a family planning doctor. An instrument called a speculum is placed in your vagina to make it easier to see your cervix. A thin tube containing the IUS is then passed up through your vagina into your womb. The tube is removed once the IUS is in place. The IUS opens up into a T-shape when it’s in your womb.
There are two strings attached to the IUS and these will hang down through your cervix into the top of your vagina.
You will usually have your IUS fitted within seven days of the start of your last period. This is when your womb lining is at its thinnest, so the IUS can be immediately effective as a contraceptive. It’s also when your cervix is slightly more open. This makes it easier to pass the IUS into your womb. If your IUS is fitted after the seventh day, you will need to use other forms of contraception, such as condoms, for another week.
You may have some pain or discomfort, similar to period pains, after having your IUS fitted. You may want to take an over-the-counter painkiller such as paracetamol or ibuprofen before you have your IUS fitted to reduce this discomfort. Always read the patient information leaflet that comes with your medicine and, if you have any questions, ask your pharmacist for advice.
You may feel faint while the IUS is being inserted, although this is unusual.
You may also have some light bleeding for the first few days after having an IUS fitted.

What to expect after having your IUS fitted

You may notice that your periods become more irregular and you may have some bleeding between them (spotting). You may also notice that your periods are heavier to start with. This should settle down within the first six months of having your IUS fitted.
After a few months, your periods should become lighter. It’s also possible that they will stop completely.

After you have had your IUS fitted you can still use tampons as they won’t change the position of the IUS in your womb. Take care when removing the tampon so that you don’t pull the threads of the IUS.

Checking your IUS

You will need to have your IUS checked between three and six weeks after it has been inserted. Your GP, gynaecologist or family planning doctor will check that it is still in the correct place and that you aren’t having any problems. The IUS can then stay in place for up to five years. You will need to have it removed and replaced after this time. When you have your IUS fitted, your GP, gynaecologist or family planning doctor will explain how you can check your IUS yourself by feeling the two threads of the IUS in your vagina. It’s important not to pull the threads. It’s a good idea to check at the end of each period because the IUS can sometimes move into the neck of your womb during your period.

It’s important to contact your GP if you:

• feel part of the IUS in your vagina
• have any discomfort after the first couple of days
• find sexual intercourse painful
• can’t feel the threads from the IUS

If this happens, it’s likely that the IUS has moved out of place and you may need to have it re-fitted. If you think it has moved, use another contraceptive method until you’ve seen your GP.

Removing your IUS

Having your IUS removed is straightforward, but don’t try to remove it yourself. Your GP, gynaecologist or family planning doctor will examine you and then remove the IUS by gently pulling on the threads that hang down into your vagina. If you don’t want to get pregnant, he or she will usually remove your IUS during your period. However, if you have not had unprotected sex for at least a week or want to get pregnant, the IUS can be removed at any time.
You may have slight discomfort for a second or two as your IUS is removed.
You can usually have another IUS fitted immediately after having your old one removed, if you wish.
The contraceptive effect of your IUS disappears as soon as it’s removed and your fertility will return to normal. If you are having your IUS replaced, you will need to use additional contraception for seven days before this just in case there is a problem with the replacement IUS. You can talk to your GP, gynaecologist or family planning doctor about your options. He or she can also tell you about alternative forms of contraception if you don’t want to get pregnant after your IUS is removed.


Side-effects are the unwanted but mostly temporary affects you may get after having the procedure. After having an IUS fitted you may have tender breasts, acne, headaches or mood changes.

There is a small chance that your IUS can be expelled after it’s inserted; over five years this happens to about one in 20 women.
It’s possible that you may develop cysts on your ovaries. These are usually harmless and cause no symptoms and they usually get better without treatment.
Very rarely, having an IUS can increase your risk of developing pelvic inflammatory disease. The symptoms of pelvic inflammatory disease include pain in your pelvis, fever and smelly vaginal discharge. These symptoms may not be caused by pelvic inflammatory disease but you should contact your GP, gynaecologist or family planning doctor for more advice, especially if you have them in the first three to four weeks after your IUS is fitted.