Hormonal IUD (Mirena IUD)

  • Over 99.5 % Effective
  • No STI Protection
  • 5 years

What is the hormonal IUD?

The hormonal intrauterine device (IUD) is a small ‘T- shaped’ plastic device. It slowly releases a hormone (progestogen) into your uterus (womb). Progestogen is similar to the hormone produced by the ovaries. It is sold as Mirena® in Australia.

Fpv Hormonal Iud
photo of hormonal IUD

How effective is the hormonal IUD?

It is more than 99% effective at preventing pregnancy and can last for up to five years.

What stops the hormonal IUD from working?

The hormonal IUD might not work if:

  • It falls out (remember to check the strings regularly)
  • Goes into the wrong position
  • It is left in for longer than 5 years 

How do I use the hormonal IUD?

The hormonal IUD is inserted inside the uterus (womb) by a trained doctor or nurse.

It has a fine nylon string attached to it which comes out through the cervix (opening to the uterus/womb). If you feel high up inside your vagina, you can check that the string is there and know the IUD is still in place. This string cannot be seen and it does not hang out of the vagina.

illustration of Hormonal IUD

How does the hormonal IUD work?

The hormonal IUD works by stopping the sperm and egg meeting and thickening the fluid around the cervix (opening to the uterus/womb). This helps to prevent sperm from entering.

illustration of mucus in cervix

The hormonal IUD also works by changing the lining of the uterus/womb. This makes it difficult for a fertilised egg to stick to the lining to start a pregnancy. 

illustration of egg not sticking to uterus lining

Sometimes the hormonal IUD can also stop the ovaries from releasing an egg.

illustration of eggs not being released by ovaries

When it is first inserted (put in) it can take up to seven days to start working.  

Where can I get the hormonal IUD?

Your doctor will write you a script and you can get the hormonal IUD from your pharmacy. You will need to return to the clinic to have the IUD inserted. If you don't have a Medicare card it will be more expensive. It will be cheaper if you have a healthcare card.

What is good about the hormonal IUD?

  • It is an extremely effective method of contraception
  • Once it’s inserted (put in) you can forget about it for 5 years
  • It can last up to 5years
  • Most users have no vaginal bleeding at all or a light regular period
  • Periods may be less painful
  • No medications stop it from working 
  • It is another choice if you have difficulty taking the hormone oestrogen. ’The Pill’ (combined pill) and vaginal ring contains oestrogen and progestogen. The hormonal IUD only contains progestogen.
  • You can use it while breast feeding
  • It is easy to remove
  • Once removed your fertility quickly returns to normal

Are there any side effects from using the hormonal IUD?

  • When it is first inserted some users have period type cramping that usually settles after a few days.
  • Your vaginal bleeding pattern/period will change. Spotting or frequent bleeding is common in the first three to six months. By six months around 95% of users will have a light regular period or no bleeding at all (this is not harmful to the body).
  • Sometimes the IUD can fall out. This is more common in the first 3 months of it being inserted.

Possible side effects for a small number of users can include:

  • Sore/ tender breasts
  • Headaches
  • Changes to your skin
  • Mood changes

These side effects nearly always settle with time. It has not been shown to cause weight gain.

Can the hormonal IUD cause any serious health problems?

  • In about 1 in 500 users, the doctor or nurse makes a small hole in the wall of the uterus (womb) while inserting the IUD. The IUD can move through the hole and sit in the wrong place. You would then need keyhole surgery to have it removed.
  • Around 1 in 300 users get an infection when the IUD is first inserted. This is usually successfully treated with antibiotics.
  • It is very unlikely to get pregnant when using the hormonal IUD. If you do get pregnant with a hormonal IUD, there is a higher chance of ectopic pregnancy. This means that the pregnancy may settle in the fallopian tubes (pathway of the egg to uterus).  

Reasons why the hormonal IUD might not be a good option for you:

  • Been treated for breast cancer
  • A uterus (womb) that is not the usual shape seen
  • Have severe liver disease

What if I can’t feel the strings?

If you can't feel the IUD string, use condoms until a doctor or nurse confirms the IUD is in the right place. If you have had unprotected sex in the five days before you notice the string missing, you might need emergency contraception.

What if I’m late having my hormonal IUD changed over?

Once the hormonal IUD is in for more than five years, use condoms until you can have it replaced.

What happens if I get pregnant while I’m using the hormonal IUD?

It is important that you see a doctor or nurse as soon as possible and have the IUD removed. The doctor or nurse will also need to rule out a pregnancy in your fallopian tubes.  If the hormonal IUD is removed, you can continue the pregnancy or have an abortion. If it cannot be removed and you continue the pregnancy, there is a high risk of losing the pregnancy.

Can I use the hormonal IUD after I’ve had a baby?

The hormonal IUD can be inserted straight after you give birth.  If not inserted straight after you give birth then you need to wait at least four weeks later. The hormonal IUD is safe to use if you are breastfeeding.

What if I’m using the hormonal IUD and I want to become pregnant?

The hormonal IUD can be removed at any time by a doctor or a nurse. Your fertility will quickly return.

What else should I know about the hormonal IUD?

  • The hormonal IUD does not protect you from sexually transmissible infections (STIs).
  • It is good to write down the date or enter that date into your phone when you had the IUD. You will need to make sure it is taken out before it expires (up to five years after being inserted).
  • Your partner might be able to feel your IUD string during sex, but it rarely causes them discomfort.
  • The hormonal IUD is one of many types of contraception. See other options.

You might be interested in watching:

A video about IUDs

Where to get more information, support or advice


Professional Training for Doctors

This is general information only, you should speak to your doctor for advice and further instruction.

Last updated: 28 June 2018