Intrauterine devices (IUD) for contraception

Easy-to-read medicine information about the intra-uterine device (IUD) – what is it, how it is it inserted and possible side effects.

Type of medicine Also called
  • Contraceptive (to prevent pregnancy)
  • Progestogen-only IUD
  • Copper-containing IUD
  • Long-acting, reversible contraceptive
  • IUD
  • IUCD
  • The 'coil'
  • Loops
  • Mirena®
  • Jaydess®

What is the intra-uterine device?

The intra-uterine device, or IUD, is a form of contraception that prevents pregnancy. 

  • An IUD is a small, T-shaped plastic device that is inserted into your uterus (womb) and has a plastic string tied to the end which hangs down through the cervix into the vagina.
  • It is a long-acting form of contraception, which means that once it is inserted you don't have to remember about it every day or every time you have sex.
  • Its effect is reversible which means that your natural fertility returns after the IUD is removed. 

What are the pros and cons of the IUD?

Pros Cons

✔ Don’t have to remember to take anything every day – IUDs can last for 3-5 years once inserted into your body. 

✔ Highly effective and reliable at preventing pregnancy in the near future.

✔  Is reversible – you can choose to have it taken out at any time. 

✔ The hormonal IUD can help you with heavy menstrual bleeding or painful periods. 

✔ Doesn't affect breastfeeding.

✔ Doesn’t interfere with having sex.

✔ M
ay reduce the risk of endometrial cancer. 

✘ May cause irregular bleeding, more bleeding or cramping initially, but this gets better over time. 

✘ May cause pain, cramps or dizziness when IUD is inserted or taken out. 

✘ Has a small risk of infection and a very small risk of damage to your womb when it is inserted. 

✘ In rare instances it can come out by itself. You will be taught how to feel and check the threads are still in the right place. 

✘ Does not protect against STIs, so it’s important to use condoms when you have sex.

Types of IUD

In New Zealand there are two types of IUDs:

  • progestogen-only or hormonal IUDs (such as Mirena®, Jaydess®)
  • copper IUD.

Hormonal or progestogen-only IUD

This is also called an intrauterine system. The hormonal or progestogen-only IUD contains a progestogen called levonorgestrel that it releases slowly into the womb.

  • It prevents fertilisation of the egg by damaging or killing the sperm. It also affects the lining of the uterus, making it unsuitable for a fertilised egg to implant and grow.
  • Progestogen hormones in this IUD also reduce menstrual bleeding and cramping. Because of this, it is often used to treat menorrhagia (heavy periods). 
  • Examples of the hormonal or progestogen-only IUD are:
    • Mirena®
    • Jaydess®. 
  • Mirena® is effective for 5 years, while Jaydess® is effective for 3 years. At the end of this time, your IUD will need to be changed.    

Copper IUD

The copper IUD works by releasing tiny amounts of copper into the womb which damages or kills the sperm, and also affects the lining of the uterus, making it unsuitable for a fertilised egg to implant and grow. 

  • The copper IUD is generally effective for 5 years and is usually changed 5 years after insertion. 
  • Your doctor will advise you if your IUD can be left for longer.   

How well does the IUD work?

Both the progestogen and copper IUDs are at least 99% effective in preventing pregnancy. This means that fewer than 1 out of every 100 women using an IUD will get pregnant each year.

Most pregnancies that occur with IUD use happen because the IUD is pushed out of the uterus unnoticed. This is most likely to happen:

  • if you have heavy or painful periods
  • if inserted just after childbirth or an abortion
  • in women who have not had a baby. 

Once inserted, the IUD is immediately effective as a contraceptive.

How is the IUD fitted?

The IUD can be fitted at any time provided you are not pregnant or do not have an infection. It is usually fitted towards the end of a period or shortly afterwards.

Before the IUD is fitted, you will need to have a vaginal examination. The doctor or nurse will pass a small instrument into your womb (uterus) to check its size and position. 

The IUD is then fitted using a small plastic insertion device.

  • Fitting an IUD can sometimes be uncomfortable. Once it has been inserted, some women have cramps and pains (like period pains) for a few hours. This may last up to about 2 days afterwards. These can be eased by painkillers such as paracetamol or ibuprofen. You may be advised to take these an hour before your fitting.
  • Light vaginal bleeding may also occur for a short while afterwards.
  • Your doctor or nurse will usually want to check that there are no problems a few weeks after fitting an IUD. This is best done after your next period. After this, there is no need for any routine check until it is time to remove the IUD. However, contact your doctor or nurse at any time if you have any problems or queries.
  • Most women have no problems, and the IUD can remain in place for several years.

Read more about how to prepare for your appointment and what to expect after IUD insertion –  Intra uterine Device (IUD) Family Planning NZ

Take care

  • You will be taught how to feel the threads of the IUD so you can check it is in place. It is best to check the threads regularly, after each period or at the beginning of each calendar month.
  • If you cannot feel the string, it doesn't necessarily mean that the IUD has been expelled. Sometimes the string is just difficult to feel or has been pulled up into the cervical canal (which will not harm you).
  • Contact your doctor or nurse if you cannot feel the IUD string.

Who should not use the IUD?

An IUD is not recommended for women who:

  • Have symptoms of genital or pelvic infection at the time of insertion. If you have a genital infection when an IUD is inserted, the infection can be carried into your uterus and fallopian tubes. Your doctor will test you and treat you if necessary before you get an IUD.
  • A copper IUD is not recommended if you have heavy or painful periods since the IUD may make them more heavy and painful.
  • If you have migraine or severe headache, jaundice (dark urine, yellow skin and eyes), increasing blood pressure, the IUD may be removed.

What are the side effects of intrauterine devices (IUD) for contraception?

Like all medicines, the IUD can cause side effects, although not everyone gets them.

Side effects What should I do?
  • Irregular, light bleeding for more days than usual
  • Bleeding or spotting in between your periods
  • This is quite common soon after you have an IUD inserted
  • If troublesome, discuss with your doctor or nurse
  • Heavy, painful periods that last longer than usual
  • This tends to be in the first few months after insertion of the IUD and often settles with time.
  • If troublesome, or ongoing discuss with your doctor or nurse

  • Signs of infection such as pain in the lower abdomen or stomach area, fever, flu-like symptoms, feeling unwell, dizziness, feeling faint or vaginal discharge
  • There is a small risk of infection especially within the first 20 days after insertion
  • Tell your doctor or nurse immediately or ring HealthLine 0800 611 116    
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product

Learn more

The following links provide further information about the IUD.

Intra-uterine Device (IUD) Family Planning NZ
Mirena Medsafe Consumer Information NZ
Jaydess Medsafe Consumer Information NZ
Contraception – the copper IUD Family Planning NSW, Australia

Chinese Simplified 

Note: In NZ, visit your family doctor or Family Planning. Cervical smears are every 3 years unless you have had an abnormal smear. 

Additional resources for healthcare professionals

Intra-uterine devices NZ Formulary
Intra-uterine progestogen-only device NZ Formulary
Copper intra-uterine device NZ Formulary
Jaydess Medsafe, NZ
Mirena Medsafe, NZ
Intrauterine devices and uterine perforation Medsafe, NZ 2014
Extended use of copper and levonorgestrel intrauterine contraceptive devices (IUDs) BPAC, NZ, 2014
Long term use of LNG-IUS (Mirena) and bone mineral density Goodfellow Gems, NZ, 2020
Educational series on long acting reversible contraception Research Review, NZ, 2020

Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 22 Jan 2019