This shows where the intra-uterine system (Mirena® in the UK) sits after insertion, within the body of the uterus. It gives off a slow release of progestogen, directly to the lining of the uterus.

IUS – Intra-Uterine System – Mirena®

The IUS – IntraUterine System
Called by some as “The Pill Coil”

The following is an extract from Sexplained Two – For Changing Times, by Helen J Knox

Used here, with permission under licence – © Helen Knox / Knox Publishing – All Rights Reserved

"Sexplained Two - For Changing Times" by Helen J Knox
“Sexplained Two – For Changing Times” by Helen J Knox
This shows where the intra-uterine system (Mirena® in the UK) sits after insertion, within the body of the uterus. It gives off a slow release of progestogen, directly to the lining of the uterus.
This shows where the intra-uterine system (Mirena® in the UK) sits after insertion, within the body of the uterus. It gives off a slow release of progestogen, directly to the lining of the uterus. © Helen Knox

What is an IUS?

IUS stands for Intra-Uterine System.

An IUS is a contraceptive device, similar to a copper coil, but with slow release hormone (progestogen) on it instead of the copper, and it is used on an IUD.

This relates to the IUS, available worldwide as  Mirena® / Levonova ® (Scandinavia) ; and the mini-IUS as Jaydess® / Skyla® (USA).


How does it work?

It releases the hormone to the lining of your womb and alters its conditions to prevent you becoming pregnant.

It thickens the mucus at your cervix, which prevents sperm entering your womb.

It prevents some women from ovulating or releasing an egg, although most women still ovulate.

How reliable is it?

Very reliable indeed.

Almost 100% of pregnancies are prevented for users of the IUS.

Mirena®  is so good that today, it’s often offered to prevent pregnancy instead of a sterilization.

Jaydess®  delivers 25% of the drug dose of Mirena®  and the failure rate is, therefore, slightly higher.


Who’s suitable to use the IUS?

Mirena®  is particularly suitable for women who’ve given birth.

Jaydess®  is particularly suitable for women who have not given birth.

But, either device can be used by either group of women.

It is sometimes inserted with local anesthetic, to make insertion more comfortable.


Can it be used for Emergency Contraception like the IUD?

No, it should not be used as a method of emergency contraception.


Who’s may not be suitable to use the IUS?

Women who are pregnant must not use it. Women who have or have had:

1. active liver infection or growth;

2. undiagnosed abnormal vaginal bleeding;

3. infection, or at risk of infection;

4. a history of cardiac (heart) or circulatory disease.


Are there any benefits from using it apart from preventing pregnancy?

Yes, there are.

It can help some women who get very heavy periods due to fibroids (noncancerous growths in the uterus) but not all; depending on the fibroid.

Periods are usually less painful, lighter and shorter, or may stop.


How is it fitted?

An IUS is inserted under sterile conditions by a specially trained healthcare professional – usually in the first week of your period although it can be inserted any time if they can be certain you are not pregnant.


When does it start to work?

It works immediately when fitted within 7 days of a period starting.

If fitted after the 7th day of a cycle,  a condom should be used for 7 days (or the previous method continued for a week, alternatively, avoid sex the first 7 days).

For how many years can I use it?

Mirena® / Levonova ® is licensed for 5 years’ use; Jaydess®/Skyla® for 3.

It can be removed sooner if you want to get pregnant and another can be inserted after removal if you want to continue with the method.

Do diarrhoea, vomiting, antibiotics or smoking affect it?

No. It is not affected by any of these.


Should I stop using the IUS and give my body a break?



Will it control my periods or make them heavier or lighter?

No. It won’t control their timing but your periods will become lighter and less painful, perhaps even stop during use.

You may experience irregular bleeding or spotting in the first few months of use.


What should I be aware of if my girlfriend’s using an IUS?

Her outward appearance doesn’t change when she’s using the IUS, so it’s up to you to help her check that it’s still in place before you have sex. You can do this during foreplay by gently checking that you can feel the threads of the IUS at her cervix.

Diarrhoea, vomiting antibiotics or other drugs won’t put either of you at increased risk of pregnancy.

Remember: your girlfriend’s not protected from sexually acquired infections when using the IUS on its own. So, if you’re unfaithful to her, you could put her at risk if you don’t use a condom. The only way to protect yourself fully from unplanned pregnancy AND infection is to use a condom during sex, at all times.

Can I use tampons with an IUS?

You should use sanitary towels (pads) during your first period in case the IUS comes out with your first period.

After that, yes, you can use tampons with an IUS.

Always check the thread(s) afterward a period, to make sure the IUS hasn’t come out.


Do recreational drugs affect its reliability?

No. Not as far as is known.

Drugs can, however, be bad for your long-term physical and mental health and can increase your risk of contracting sexually acquired infections.

If you dehydrate you are more likely to get thrombosis (blood clots).


Will the IUS make me put on weight?

No, not as far as is known.


Will it protect me from pregnancy AND infection?

No, it won’t protect you from infection. You still need to use a condom.


Is it reversible?

Yes, completely, upon removal.


Do I have to have sex to use it?

No – see the list of benefits on the previous page.


IUD – Coil – Intra-Uterine Contraceptive Device (IUD/IUCD)

What causes the infections and what infections do they cause ?

Emergency Contraception / EHC / “Morning After Pill”

Male and Female Sterilisation

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