The video will provide you with an overview of how the intrauterine system (IUS) provides contraceptive protection.
How does the intrauterine system (IUS) work? The video will provide you with an overview of how the intrauterine system (IUS) provides contraceptive protection. Read video transcript
Close transcript

How does the intrauterine system (IUS) work?

  • The IUS is put in place by a healthcare professional
  • The IUS releases low levels of a hormone
  • In some women ovulation (release of the egg) may be prevented
  • The hormone causes thickening of the cervical mucus, making it harder for sperm to pass into the womb
  • The hormone also thins the womb lining, which can lead to a reduction in menstrual bleeding; and many women may eventually have no periods at all
  • The IUS provides contraceptive protection for up to 5 years

Intrauterine system (IUS)

Also known as the ‘hormonal coil’

The intrauterine system is a small, T-shaped frame made from soft, flexible plastic. The T-shaped frame is around 3 cm long and wide. The vertical arm is surrounded by a narrow cylindrical-shaped reservoir that contains levonorgestrel, a progestogen (hormone)1. The reservoir releases a very low daily dose of the hormone in the womb, where it exerts its contraceptive effect1. Only very small amounts of hormone can be found in the blood.

The intrauterine system has two removal threads that extend from the lower part of the T-frame to the upper part of the vagina2.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

How the intrauterine system works

The intrauterine system has several effects on your body, which together make it a highly effective contraceptive option. Levonorgestrel, the active ingredient that is released from the intrauterine system cylinder, causes thickening of the cervical mucus (the fluid secreted by glands around the cervix, the neck of the womb), thus making it harder for sperm to pass through the birth canal1. In addition, it prevents thickening of the womb lining and in some women ovulation (release of the egg) may be prevented1.

Levonorgestrel, the progestogen hormone contained within the intrauterine system, is released at a low dose. The intrauterine system is the only long term hormonal contraceptive that exerts its contraceptive effect mainly locally in the womb. Consequently, the hormone levels in the bloodstream will be low which may help to reduce the risk of hormonal side-effects. All other long-acting hormonal contraceptive options exert their contraceptive effects after take-up of the hormone in the bloodstream, meaning that the hormone concentration is similar throughout the body.

Although the intrauterine system starts working as soon as it is placed, it is advised to wait about 24 hours before having sexual intercourse, to give your body a rest2.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Before placement of the intrauterine system

Before the intrauterine system is placed in your womb, your healthcare professional will perform a series of health checks. These may include a cervical smear test (Pap smear), examination of the breasts and other tests, e.g. for infections, including sexually transmitted diseases, as necessary. A gynecological examination should be performed to determine the position and size of the womb2.

The intrauterine system is not suitable for use as a post-coital contraceptive (i.e. after unprotected sexual intercourse).

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Placement of the intrauterine system

The intrauterine system is placed in your womb by a healthcare professional. It is a routine procedure that normally takes just a few minutes following your pelvic examination. Most women find the placement procedure only causes minor discomfort. However, you can discuss with your healthcare professional in advance whether some measure of pain management may be appropriate for you.

Placement of an intrauterine system (IUS).Once your cervix has been cleaned with an antiseptic solution, the depth of the uterine cavity is measured and the intrauterine system is placed into the womb via a thin, flexible plastic tube.

The intrauterine system can be placed within seven days from the start of your period2. It can also be placed immediately after an abortion, provided that there are no genital infections2. It should be placed only after the womb has returned to its normal size after childbirth, and not earlier than 6 weeks after having given birth2. The intrauterine system can be replaced by a new system at any time of the cycle2.

When the intrauterine system is used to protect the lining of the womb for women on estrogen therapy, it can be placed at any time in an amenorrheic woman (a woman who has no monthly bleeding), or during the last days of menstruation or withdrawal bleeding2.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Check-ups after placement of the intrauterine system

You should have an initial check-up at 4 - 12 weeks after placement2. Subsequent check-ups should be at least once a year2. You should contact your healthcare professional if you experience any of the following2:

  • you no longer feel the threads in your vagina
  • you can feel the lower end of the intrauterine system
  • you think you may be pregnant
  • you have persistent abdominal pain, fever, or unusual discharge from the vagina
  • you or your partner feel pain or discomfort during sexual intercourse
  • there are sudden changes in your menstrual periods (for example, if you have little or no menstrual bleeding, and then you start having persistent bleeding or pain, or you start bleeding heavily)
  • you have other medical problems, such as migraine headaches or intense headaches that recur, sudden problems with vision, jaundice, or high blood pressure
  • you experience any of the conditions mentioned in the When should you not use the intrauterine system? section below.2

After 5 years, the intrauterine system should be removed. If you want a new intrauterine system, your healthcare professional can remove the intrauterine system and immediately, during the same visit, place a new one.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Removal of the intrauterine system

Your intrauterine system should be removed by a trained healthcare professional by pulling on the removal threads. Removal is usually a painless procedure. Fertility returns to normal immediately after removal3.

If pregnancy is not desired, the removal should be carried out during a period in women of fertile age, provided that there appears to be a menstrual cycle2. If the system is removed in the mid-cycle and you have had intercourse within a week, you are at risk of pregnancy unless a new system is placed immediately following removal2.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Effectiveness of the intrauterine system (in preventing pregnancy)

The intrauterine system can provide you with contraceptive protection for up to 5 years. Pregnancy rates with this type of contraceptive are very low. Only around 2 per thousand women may become pregnant in the first year4. By using the intrauterine system, which is permanently in place, no pregnancies occur due to problems remembering to use or take a contraceptive.

Women who rely on their partner using condoms can typically experience a pregnancy rate of as high as 180 per thousand women per year (only 20 per thousand if used perfectly)4.

As with other long-acting reversible contraceptives (LARC), the intrauterine system offers the advantage of a contraceptive that you don’t have to think about and which doesn’t spoil the spontaneity of sex.

You should tell your healthcare professional if you are taking or have recently taken any other medicines, including medicines obtained without a prescription2. Since the mechanism of action of the intrauterine system is mainly local, taking other medications is, however, not believed to have major importance for the contraceptive effectiveness of the intrauterine system2.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Return to fertility after using the intrauterine system

There is no effect on fertility, and after your intrauterine system is removed, your fertility returns to ‘normal’ as before placement3.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Using the intrauterine system while breastfeeding

The intrauterine system can be put in place after the womb has returned to its normal size, but at the earliest from six weeks after having given birth. It is then safe to breastfeed, as no negative effects on infant development or growth have been observed2.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

The intrauterine system & heavy menstrual bleeding

Heavy periods can be a serious enough issue to consider having gynecological surgery that could be a hysterectomy (womb removal) or a surgical procedure on the lining of the womb (the endometrium) if drug treatment does not work. However, one form of long-acting reversible contraception (LARC) (the intrauterine system) is recommended as a treatment for women with heavy periods as it is has been medically proven to significantly reduce bleeding in addition to providing effective contraceptive protection1.

There is a significant reduction in menstrual blood loss (79% – 98%) after 3 to 6 months of treatment. The first couple of months are characterized by an increase in total bleeding days (menstrual days and intermenstrual spotting days combined)(15-21), although the amount of blood loss is reduced quite soon after the intrauterine system placement.

If a significant reduction in blood loss does not occur after 3 to 6 months, alternative treatments for heavy menstrual bleeding (pharmaceutical or surgical) should be considered.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

The intrauterine system & estrogen therapy

The onset of the menopause signals the decline of your reproductive capability and you may experience hot flushes and other symptoms. Your doctor may recommend using hormone replacement therapy (HRT) to compensate for the loss of estrogen production by your body. It does not necessarily mean that contraception is no longer needed. Hormone replacement therapy (HRT) for menopausal symptoms does not provide contraceptive protection. If you need HRT, you can use the intrauterine system together with estrogen replacement therapy (ERT)1. This combination simultaneously provides contraception and HRT. The intrauterine system protects your womb lining (the endometrium) from a condition known as hyperplasia, which is an abnormal thickening that can be caused by ERT1.

Women who have had a hysterectomy (surgical removal of the womb) can take ERT alone to treat menopausal symptoms. Women who opt for HRT who have not had this procedure can use the intrauterine system, in conjunction with ERT, to provide the progestogen component of HRT for up to five years1. The estrogen component can be chosen from the available options that include pills, patches, creams and gels.

For women who use the intrauterine system in conjunction with ERT, there may be some spotting (a small amount of blood loss) and irregular bleeding during the first few months after placement. Eventually, this bleeding will reduce and eventually you may have no bleeding or spotting at all1.

Ask your healthcare professional for more advice.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

Side-effects & the intrauterine system

Changes to your periods


More than 10 in every 100 women are likely to experience changes to their periods following placement of the intrauterine system.

The intrauterine system can affect your periods in different ways. You may experience spotting (a small amount of blood loss), and the length of your periods and amount of bleeding may differ2. Overall, there will be a reduction in the number of bleeding days and in the amount of blood lost each month. Some women eventually find that their periods stop altogether2. When the intrauterine system is removed, periods return to normal.

Other side-effects2

Very common and common side-effects

Very common side-effects in more than 1/10 women Common side-effects in more than 1/100 women
  • headache
  • abdominal/pelvic pain
  • vulvovaginits (inflammation of the external genital organs or vagina)
  • genital discharge
  • depressed mood/depression
  • migraine
  • nausea (feeling sick)
  • hirsutism (excessive body hair)
  • acne
  • back pain
  • upper genital tract infection
  • ovarian cysts (small fluid-filled sacs that develop in the ovaries that usually disappear on their own but sometimes cause mild abdominal pain. On rare occasions they may lead to more serious problems).
  • dysmenorrhea (painful menstruation)
  • vaginal discharge
  • breast pain
  • intrauterine contraceptive expelled (complete and partial)



For a comprehensive list of side-effects, including those that are uncommon and rare, as well information on specific areas of concern, go to the side-effects: intrauterine system (IUS) page.

Note: The intrauterine system (IUS) is also known as the ‘hormonal coil’.

When should you not use the intrauterine system?

There are a number of medical conditions2 which may make it unsuitable for you to use the intrauterine system if you:

  • are pregnant or think you might be pregnant
  • currently or recurrently have a pelvic inflammatory disease (infection of the female reproduction organs)
  • have a lower genital tract infection
  • have an infection of the womb after delivery
  • have had an infection of the womb after abortion during the past 3 months
  • have an infection of the cervix (neck of the womb)
  • have cell abnormalities in the cervix
  • have cancer or suspected cancer of the cervix or womb
  • have tumors which depend on progestogen hormones to grow
  • have unexplained abnormal vaginal bleeding
  • have an abnormality of the cervix or womb including fibroids if they distort the cavity of the womb
  • have conditions associated with increased susceptibility to infections
  • have an active liver disease or liver tumor
  • are hypersensitive (allergic) to levonorgestrel or to any of the other ingredients of the intrauterine system.

Conditions which may exist or appear for the first time

If any of the following conditions exist or appear for the first time while using the intrauterine system, you should consult a specialist who may decide to continue or to remove the intrauterine system2:

  • migraine, asymmetrical visual loss or other symptoms which may be signs of a transient cerebral ischemia (temporary blockage of the blood supply to the brain)
  • exceptionally severe headache
  • jaundice (a yellowing of the skin, whites of the eyes and/or nails)
  • marked increase of blood pressure
  • severe disease of arteries such as stroke or heart attack.

Use with caution

  • the intrauterine system may be used with caution in women who have congenital heart disease or valvular heart disease at risk of infective inflammation of the heart muscle2. Antibiotic preventive medication should be given to such women when placing or removing the intrauterine system2
  • for diabetic users of the intrauterine system, the blood glucose concentration should be monitored. However, there is generally no need to change your diabetic treatment when using the intrauterine system2
  • irregular bleedings may mask some symptoms and signs of endometrial polyps or cancer, and in these cases diagnostic measures have to be considered2
  • available data shows that the intrauterine system does not increase the risk for breast cancer in fertile women under 50 years of age2
  • the intrauterine system is not the method of first choice for young women who have never been pregnant, nor for postmenopausal women with shrinking of the womb2

Your contraceptive choices

FAILURE RATE

FAILURE RATE

FAILURE RATE

FAILURE RATE

2| 1,000WOMEN(number of pregnancies after one year of use)
6-8| 1,000WOMEN(number of pregnancies after one year of use)
2-60| 1,000WOMEN(number of pregnancies after one year of use)
< 1| 1,000WOMEN(number of pregnancies after one year of use)

ADMINISTRATION

ADMINISTRATION

ADMINISTRATION

ADMINISTRATION

Placement in womb
Placement in womb
Injection in arm or buttock
Placement under the skin of arm

LENGTH OF PROTECTION

LENGTH OF PROTECTION

LENGTH OF PROTECTION

LENGTH OF PROTECTION

Up to 5 years
Up to 5 to 10 years, depending on model
12 weeks
Up to 3 years

RETURN TO FERTILITY

RETURN TO FERTILITY

RETURN TO FERTILITY

RETURN TO FERTILITY

No delay
No delay
Possible delay of up to 1 year following treatment cessation
No delay

MENSTRUAL BLEEDING

MENSTRUAL BLEEDING

MENSTRUAL BLEEDING

MENSTRUAL BLEEDING

  • Initially periods may be lighter or heavier, longer or shorter or absent.
  • Infrequent or absent periods likely after several months.
  • Bleeding and spotting days may increase in first few months.
  • Bleeding may be heavier.
  • Irregular and possibly lengthy bleeding or spotting or no bleeding at all.
  • Periods may become more or less frequent, continuous or absent.
  • May reduce or increase in intensity or duration.

BODY WEIGHT

BODY WEIGHT

BODY WEIGHT

BODY WEIGHT

No effect
No effect
May cause weight gain of 2.3 – 3.6 kg in the first year
No effect

USE DURING BREASTFEEDING

USE DURING BREASTFEEDING

USE DURING BREASTFEEDING

USE DURING BREASTFEEDING

  • Yes
  • 6 weeks after birth
  • Yes
  • 6 weeks after birth
  • Yes
  • 6 weeks after birth
  • Yes
  • 4 weeks after birth

HEAVY PERIOD TREATMENT

HEAVY PERIOD TREATMENT

HEAVY PERIOD TREATMENT

HEAVY PERIOD TREATMENT

Yes
No
No
No

USE IN ESTROGEN THERAPY

USE IN ESTROGEN THERAPY

USE IN ESTROGEN THERAPY

USE IN ESTROGEN THERAPY

Yes – Recommended for use in conjunction with estrogen replacement therapy
No – Not recommended for use in conjunction with estrogen replacement therapy
No – Not recommended for use in conjunction with estrogen replacement therapy
No – Not recommended for use in conjunction with estrogen replacement therapy