Everything you need to know about the hormonal coil (IUS)

Reviewed: May 7, 2021
The hormonal coil (also known as IUS) is one of the most effective forms of contraception the UK

The small but mighty hormonal coil (IUS) always manages to raise a lot of curiosity and often gets countless questions – ‘What is an IUS?’ ‘What is the difference between IUS and IUD?’ ‘Is it effective?’ – are just some to name a few.

Being one of the most effective forms of birth control in the UK, it’s not surprising that there is so much interest around the hormonal IUS coil, as it can definitely be hard to to get your head around how this tiny ‘T’ is packed full of hormones and can work so well to prevent pregnancy.

What is the IUS coil?

The hormonal coil (IUS) is a small, T-shaped plastic device that is inserted into your womb by a doctor or nurse. It can protect against pregnancy for between 5-10 years and is 99% effective. Not only does the device protect from pregnancy, but it can also help to make heavy periods lighter and less painful; 54% of the Lowdown users say that it stopped their periods completely – where do I sign up?!

How does the IUS work?

The device works by gradually releasing the hormone progestogen into the womb, which prevents pregnancy by making the fluid in your cervix thicker, making it more difficult for the sperm to get into the womb. It also thins the lining of the womb, so the egg is less likely to be able to implant itself.

How is the IUS coil inserted?

To get the coil inserted, you’ll need to go to a GP surgery or sexual health clinic where they have trained specialists to fit the coil. I’d recommend contacting your GP surgery first to double-check that they offer the service.
The coil can be fitted at any time during your monthly period cycle (as long as you’re not pregnant). But for your comfort, it might be best to get it fitted when you’re not on your period.

Your doctor or nurse will do some tests to make sure that you are eligible for the coil, like checking for any infections or STIs. They will then use a speculum (similar to when you have a smear test) to open up your vagina and insert the coil through the cervix into the womb – this may be a little uncomfortable.

If it’s fitted in the first 7 days of your cycle, you’ll be protected against pregnancy straight away. However, if it’s fitted at any other time, you’ll need to use another form of contraception for 7 days after. The normal procedure is to go back for a check-up 3-6 weeks after getting fitted – just to check everything is running smoothly.

How do I check it’s still in place?

The coil has 2 thin threads that hang slightly down from your womb into the top of your vagina. The doctor or nurse that fits your device will teach you how to feel for these threads to check that it’s still in place. It’s advised to check that your coil is in place a few times in the first month and then at regular intervals after each period.
It’s highly unlikely that your IUS will come out, but if you can’t feel the threads or think that it might have moved, you may not be protected against pregnancy – make sure to book an appointment with your GP to get this checked and use another form of protection to avoid pregnancy.

What about hormonal coil removal?

You can have the coil removed at any time, but must be done by a doctor or nurse – DO NOT attempt this yourself. They will gently pull on the threads to encourage the ‘T’ shape to fold up which can then be easily pulled out of the womb. If you’re not having the coil replaced and you don’t want to get pregnant, you will need to make sure not to have sex seven days before having it removed – or make sure to use condoms. In fact, having the coil removed is actually easier than having it fitted.


The IUS (hormonal coil) and the IUD (copper coil) are very similar, however, the one significant difference being HOW they prevent pregnancy. The IUS works by releasing the hormone progestogen into the body, whereas the IUD releases copper into the body to prevent pregnancy. The IUD is often favoured amongst women as it is completely hormone-free.

Pros and Cons of the IUS coil


  • Lasts for 3-5 years
  • It can help make heavy periods lighter and less painful
  • You don’t need to remember to take contraception every day
  • It can stop ovulation completely – which appeals to some women
  • It’s not affected by other medicines


  • Can be a small risk of infection after having it fitted. This can occur when harmless bacteria, normally found in the vagina, is pushed inside the womb. It can be easy to know when it’s infected if you have any unusual discharge or you develop a high temperature or chills
  • Around 1 in 20 coils can fall out or be pushed out by the womb; this is most common in the first few weeks after the fitting or during a period. If this happens, head to your doctor or nurse to discuss what to do next
  • If the coil doesn’t work and you get pregnant, there is a small increased risk of ectopic pregnancy
  • Very occasionally the threads can get lost (but only happens to around 1 in 100 women)
  • Even more occasionally (1 in 1000 chance), the coil can go through the wall of the womb into the abdomen.

Who should use an IUS?

  • Women that don’t want a contraceptive that needs to be remembered daily
  • Women that have heavy periods
  • Women that are breastfeeding

Who shouldn’t use an IUS?

  • Women that have or have had breast cancer in the last 5 years
  • Women that have problems with their womb or cervix
  • Women that have arterial disease or a serious history of heart disease or strokes
  • Women that have unexplained bleeding between periods or after sex

Where can I get an IUS?

The hormonal coil is available from contraception clinics, sexual health clinics, GP’s surgeries and young people’s clinics – being a really popular form of contraception in the UK means it’s super easy to get hold of.

Many women favour this method of contraception based on its longevity and practicality, however, others prefer a method that doesn’t need to be inserted into the cervix or could potentially stop their periods.

To find out about non hormonal coil read our guide to the IUD.

This guide was brought to you by The Lowdown. We are the world’s first contraception review platform, providing real-life experiences from thousands of reviews collected from our community of men and women.

Why not leave us a review of your contraceptive experience? Whether you’ve got good things to say about the Mirena coil or had trouble with implant removal, we want to hear about it! Tell us about your experience and help people around the world find the right method for them.