Levonorgestrel Intrauterine Device (LNG-IUD)

A levonorgestrel intrauterine device (LNG-IUD) is a small, plastic, T-shaped device containing the hormone levonorgestrel (progestogen) that sits inside the womb
Also known as the ‘hormonal coil’
Over 99% effective
Prevents pregnancy by releasing progestogen which thins the lining of the womb
Lasts 3–8 years depending on the brand
Fitted and removed by a specialist doctor or nurse
Does not protect against sexually transmitted infections (STIs)

An LNG-IUD contains a hormone called progestogen
Progestogen thins the lining of the womb so that a pregnancy cannot develop (implant)
It also thickens the mucus in the cervix (neck of the womb), preventing sperm from entering the womb
There are several types of LNG-IUD available
In the UK we use Mirena^®, Levosert^®, Benilexa^®, Jaydess^® and Kyleena^®
Over 99% effective: less than 1 person per 100 users will fall pregnant within a year

An LNG-IUD does not always work straight away, it depends when it is fitted:

If an LNG-IUD is fitted within the first 7 days of your period, it will work straight away
If an LNG-IUD is fitted after day 7 of your period, you must use another contraceptive (e.g. condoms) for 7 days. This is because it will take 7 days for the LNG-IUD to start working
An LNG-IUD can be fitted 4 weeks after childbirth or within the first 48 hours of delivery. You cannot get pregnant within 21 days of childbirth, but you must use additional contraception after this time. If an IUS is fitted more than 21 days after childbirth, you should use condoms for 7 days
It works straight away if fitted within 5 days of complete miscarriage or abortion. If it is fitted after this, you must use condoms for 7 days

Irregular bleeding can occur, especially in the first few months. This is a process and not a genuine side effect. It represents the lining of the womb thinning and usually settles with time
Periods often get lighter and may stop altogether. This is safe and nothing to worry about
Acne, breast tenderness and mood changes can sometimes occur
Future fertility is not affected by an LNG-IUD; you can become pregnant as soon as it is removed
There is a small risk of infection and/or damage to the womb when it is fitted (called a perforation)
There is also a small risk the LNG-IUD falls out (called an expulsion). This is usually within the first 3 months after insertion
Although the LNG-IUD is very effective, if a pregnancy did occur, there is increased risk this would be an ectopic pregnancy. This is when a pregnancy develops outside the womb, such as in the fallopian tube

A specialist nurse or doctor will fit the LNG-IUD for you
You will be examined to assess the size and position of your womb
A speculum is used to open the vagina and visualise the cervix (neck of the womb)
The LNG-IUD is gently inserted through the cervix and into the womb
A local anaesthetic can be used to reduce any pain
The procedure is very quick and will only take a few minutes
You may experience some cramping and bleeding afterwards, but this will settle down in a few days

The LNG-IUD contains two soft threads attached to the bottom of the device
These threads pass through the cervix and sit at the top of the vagina
Your partner will not be able to feel the threads during sexual intercourse
You can check the LNG-IUD is still in place by inserting a finger into the top of the vagina and feeling for the threads
It is important to regularly check your threads so that you know the LNG-IUD is still in place
If you can no longer feel the threads, speak to your doctor and use another method of contraception until it can be identified. This is because the LNG-IUD might have fallen out

The LNG-IUD provides contraception for 3–8 years depending on the type you have:
- Mirena^®, Levosert^® and Benilexa^® are effective for up to 8 years
- Kyleena^® is effective for up to 5 years
- Jaydess^® is effective for up to 3 years
You will be provided with written information advising you when your LNG-IUD needs to be changed
A specialist nurse or doctor can remove the LNG-IUD for you at any time
A speculum is used to find the threads of the LNG-IUD. It is removed by gently pulling on the threads

You can get an LNG-IUD fitted free of charge at:

An LNG-IUD is safe to use in the majority of users; however, there are some circumstances where it may not be appropriate.

Always discuss with the doctor or nurse if:

There is a chance you are already pregnant
You have symptoms of infection or have been recently diagnosed with an STI such as chlamydia or gonorrhoea
Your womb is an abnormal shape
You have a history of breast, cervical or womb cancer or severe liver disease
You have bleeding in between your periods or after sex which has not been investigated

Written by Dr David Rook and Dr Paula Briggs
Reviewed and edited by Dr David Rook
Last updated: July 2025 by Dr David Rook

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