This page gives you information about the hormone coil recommended by your doctor.

What is a Mirena® intrauterine system?

This system is like many other types of coil. Mirena® will be fitted by a doctor and stay in the womb for a fixed period of time. It is much more effective than usual coils and has fewer side effects, making periods lighter.

Mirena® is made of a plastic, T-shaped frame which contains a low dose of hormone, also used in contraceptive pills but contains no oestrogen.

How effective is this contraception?

Mirena® is very effective compared to other forms of contraception. It acts in 2 ways; preventing sperm from getting through thicker mucus and making the lining of the womb extremely thin, stopping implantation.

In some women it can prevent egg release or ovulation.

If Mirena® does happen to fail, there is a higher risk of ectopic pregnancy. This is a pregnancy found outside the womb.

If you feel at any time that you may be pregnant, it is important to see your doctor to discuss your coil.

Fitting the Mirena®

The doctor will perform an internal examination to make sure there is nothing unusual before fitting the Mirena®. The coil is inserted either within a week of beginning your period, immediately after a termination or 6 weeks after having a baby.

Fitting the Mirena® is similar to having a smear test. A local anaesthetic may be used if needed. You will not be able to feel the Mirena® once fitted.

You will receive a follow appointment for about 6 weeks after the Mirena® is fitted.

Your partner should not be aware of the Mirena® during intercourse.

Removing or changing the Mirena®

Mirena® will last 5 years and if needed, a new one can be inserted at the same time the old one is removed. Removing the coil is only uncomfortable for a short time.

After the removal of the Mirena® your periods and fertility will return within a month.

Side effects

In the first months of use, there is a very small chance that the Mirena® may dislodge and come out. There may be bleeding, sometimes with pain.

There is a slight increase in progesterone levels which can cause headaches, water retention, breast tenderness or acne. This can also increase the chance of ovarian cysts.

After having the Mirena® fitted it can take from 3 to 6 months for the bleeding to settle down.

Contact information

If you have any questions, please contact your own consultant’s secretary.

Further information

For further information, please visit the following website then search for Mirena® IUS:


Printable version of this page

Mirena® intrauterine system GHPI0460_01_24 Department: Gynaecology Review due: January 2027 PDF, 273.1 KB, 3 pages
Reference number GHPI0460_01_24
Department Gynaecology
Review due January 2027