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Having a coil (Mirena) fitted

BMJ Group Medical Reference


This information is for people who have heavy periods. It tells you about having a coil (Mirena) fitted, a treatment used for heavy periods. It is based on the best and most up-to-date research.

Does it work?

We're not certain. There are problems with some of the research into this treatment. But if you're thinking about having an operation because your periods are heavy, you may want to try having this type of coil fitted first. Some women have been so pleased with the results they have cancelled surgery.

The National Institute for Health and Clinical Excellence (NICE), the government body that decides which treatments should be available on the NHS, says that having a coil fitted is the first treatment women with heavy periods should consider. [68]

What is it?

It's a type of coil that releases the hormone progestogen into the womb. The brand name is Mirena. It also works as a contraceptive. You may have heard this called an IUD ( intrauterine device) or an IUCD (intrauterine contraceptive device). It's also called the IUS (intrauterine system).

Mirena is a T-shaped plastic frame about half the length of your thumb. It contains progestogen in a form called levonorgestrel, which is released in a fixed amount each day.

You should only have a coil fitted by a doctor or nurse who has been specially trained. He or she will slide the IUD through your vagina and into your womb. The arms of the 'T' fold downwards and, when it's in place, the arms open up again.

Being fitted with an IUD may be a little uncomfortable, so you may have a local anaesthetic. But the IUD shouldn't hurt after a day or two. You can leave the Mirena IUD in your womb for five years.

How can it help?

  • This type of IUD may be better than some of the drugs available for heavy periods. [69]

  • If you are thinking about having an operation to remove the lining of your womb or an operation to remove your whole womb (a hysterectomy), you may decide you don't need surgery after you've had an IUD fitted. [69] In one study, two-thirds of women cancelled their hysterectomy six months after getting this type of IUD because they were so pleased with the results. [69]

  • An IUD that releases progestogen works just as well as an operation to remove the lining of the womb (called thermal balloon ablation). [38] [70] In one study, an IUD worked better than an operation. [71]

How does it work?

By releasing the hormone progestogen into your womb, this device stops the lining of your womb (your endometrium) preparing for a fertilised egg by getting thicker and softer.

As a result, there is less womb lining to come away during your period and less bleeding. [72]

To read more about what happens during your period, see What are heavy periods?

Last Updated: August 15, 2013
This information does not replace medical advice.  If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.

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