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The IUD and IUS Contraceptive Guide

The IUD and IUS can cause confusion for obvious reasons. Not only are they so similar in name, but they are both comparable forms of contraception. The IUD stands for intrauterine device whilst the IUS stands for intrauterine system. For further information regarding thing two forms of long-term contraception, you can read below.

What is an IUS? What is an IUD?

The similarities with both these forms of contraception is the size and shape; the IUD and the IUS are T-shaped devices that are measured and inserted into the vagina by a medical professional to stop unwanted pregnancy. The key difference is HOW they prevent pregnancy:

  • IUS releases the hormone progestogen to prevent pregnancy.
  • IUD is made of copper, which is released to prevent pregnancy.

What is a intrauterine device (IUD)?

The IUD may also be referred to as 'the coil' and tends to be the more popular out of the two devices. It is classed as a long-acting reversible contraceptive (LARC) that is inserted into your vagina where it stays until it needs to be replaced, you wish to fall pregnant or you would like to change contraceptive method.

  • Some IUDs contain copper whilst others are made from plastic.
  • It is a T-shaped device that fits into the palm of your hand.
  • It lasts for 5-10 years, but can be taken out sooner if you wish.
  • It works immediately and can be inserted at any point in the month.
  • It doesn't protect against sexually transmitted infections (STIs).

What is a intrauterine system (IUS)?

The IUS is occasionally referred to as 'the coil' but this is generally reserved for the IUD. It is classed as a long-acting reversible contraceptive (LARC) that is inserted into your vagina where it stays until it needs to be replaced, you wish to fall pregnant or you would like to change contraceptive method.

  • IUS is a T-shaped device that fits into the palm of your hand.
  • It is made from plastic and releases progestogen.
  • It lasts for 3-5 years, but can be taken out sooner if you wish.
  • It works immediately and can be inserted at any point in the month.
  • There are 2 brands in the UK; Mirena and Jaydess.
  • It doesn't protect against sexually transmitted infections (STIs).

How the IUD/IUS prevents pregnancy

The IUD and IUS are similar devices but they do work in slightly different ways.

  • The IUD is made of copper that works as a spermicide. This metal is released and prevents sperm from surviving in the womb. It often stops fertilised eggs from implanting in the womb as well.
  • The IUS releases the hormone progestogen, which thickens the cervix mucus and womb fluid, similar to the mini pill.

Advantages and disadvantages of the IUD/IUS

The main advantages of the IUD and IUS is the effectiveness rate for preventing pregnancy. However, like other forms of contraception, there are additional benefits as well.


  • The longevity of the devices makes this contraception very low maintenance. Instead of remembering to take a pill everyday, the IUD can last up to 10 years and the IUS up to 5 years.
  • They can be used when breastfeeding without influencing the mother's milk.
  • They can be removed any time you wish and your fertility returns back to normal.
  • If you fall ill and have diarrhoea or vomit, the effectiveness of the IUD/IUS is not compromised. This is the same for taking medications.
  • They are good options if you're sensitive to oestrogen.
  • They can reduce pain and discomfort associated with your period. This includes cramps, length of your period and heavy flow. For some women, the IUS stops periods entirely.


  • Both devices do not offer protection for sexually transmitted infections. The only contraceptive that significantly reduces your chances are barrier methods such as condoms.
  • Some women experience spotting and bleeding. This often stops after a few months but if it doesn't, you can get the device removed.
  • The devices can make periods heavier, painful and longer. Again, this may improve after a few months and may not be the case for every woman.
  • Some women don't want to stop their periods as it's a good indication the contraceptive has worked, and maybe they aren't so troublesome in the first place.
  • Side effects can include headaches, acne and breast tenderness. Again, this should reduce over time.
  • Whilst uncommon, one disadvantage of the IUS are cysts on the ovaries. These are usually small and can disappear without treatment.

Getting an IUD/IUS fitted

To get an IUD or IUS fitted, you must first book a doctor's appointment. Not every doctor's surgery will have this service, or only particularly nurses can fit the device, so ensure you tell the receptionist when booking the appointment.

You will be asked a number of questions before the fitting to confirm this is the right form of contraception for you. This includes being tested and treated for STIs if required. You will also need to decide the timespan.

Do remember that you can have the device removed earlier than expected for whatever reason, even if you opted for a 5-10 year contraceptive protection.

  • IUD and IUS can be fitted at any point in your menstrual cycle.
  • You will be protected straight away with the IUD. For the IUS, if fitted during the first 7 days of your cycle, you will immediately protected. Any other time of the month and you will need to use condoms for the following 7 days.
  • A fitting includes a physical examination to determine size and placement of the device.
  • The procedure takes approximately 20 minutes to complete. It is similar to a smear test.
  • This can be uncomfortable and sometimes painful for some women. You can ask for pain relief if you wish.

After the procedure

It's natural to feel cramping. This varies in duration depending on the individual. You may wish to book a day or two off work to see how you feel. A little bleeding is also possible.

Alternatively there are many women who feel minimal discomfort and cramping. You are best in tune with your body to know. If at any point the pain is too much, don't be afraid to contact your doctor's surgery for advice.

If you experience pain in the lower abdomen, have a high temperature or notice an odour to your discharge, speak to the local GUM clinic or doctor as soon as you can.

Is it still in place?

Both the IUD and IUS have threads that hang down similar to a tampon, but these remain inside the vagina. These won't be noticeable and your GP will tell you how to locate them during your fitting.

The probability of your device falling out is very unlikely but it's good to know the protocol if it happens to you. This is also called IUD/IUS expulsion.

IUD/IUS expulsion is not as noticeable as you would think. In fact, for many women there are no symptoms of the device coming out of the uterus whatsoever. This is why it's important to check your device periodically. If the IUD/IUS has moved, you're at risk of falling pregnant. If you know what to look out for, you're in the best scenario to remain protected.

  • When the IUD/IUS is first fitted, it's best to check a handful of times in the first month, then maybe once or twice month from then on. This way you get use to the device.
  • In terms of checking, you might have peace of mind doing this everyday. It's entirely up to you.
  • The thread(s) hang near the opening of the vagina. Before checking, wash your hands thoroughly.
  • Then sit or squat in a comfortable position, put your index or middle into your vagina. Locate your cervix – it's easier than you think! The cervix feels firm, it has been describe as the tip of your nose.
  • From here, you should be able to feel the strings. This should just be the end.
  • If you feel something hard, that could be the end of the device. Or if the strings feel shorter or longer than last time, this could mean the device has moved.
  • Do not try and move the IUD/IUS yourself, or pull on the strings. Book an appointment with your doctor or head to a sexual health clinic to get it checked out.

During pelvic examination and smear tests, you can also ask your doctor to check your IUD/IUS. They can move the strings to an easier place when they finish.

Precautions/interactions of the IUD/IUS

Any complications associated with the IUD and IUS are rare, however, they can happen and this tends to be within the first few months of having the device inserted.

These devices are well-tolerated for most and can be used if you're HIV positive. Before having a fitting, you will need to be clear of any STIs. You shouldn't have an IUD/IUS if…

  • You have a pelvic infection.
  • You have an issue with your cervix or womb.
  • You have any unexplained bleeding.
  • You need to tell your doctor if…

    • You've had an ectopic pregnancy.
    • You've had a recent abortion (excluding inserting the IUD as a form of emergency pregnancy).
    • You have an artificial heart valve.
    • Risks of the IUD/IUS

      The NHS states that there are "fewer than one in 1,000 cases" where the device will damage the womb. If you have pain in the lower abdomen, this could be the cause.

      "Fewer than one in 100" will experience a pelvic infections. Other risks include rejection that was mentioned above and ectopic pregnancy if your IUD/IUS fails and you don't realise you've fallen pregnant.

Where can I get an IUD/IUS fitted

The IUD and IUS should ALWAYS be fitted by a medical professional. Once inserted, it should ONLY be removed by a medical professional.

The IUD/IUS can be fitted at certain doctor's surgeries, but do check before you make an appointment to avoid wasting your time. There is usually a special nurse or doctor that does the fittings.

GUM clinics (genitourinary clinics) and STI clinics can insert the IUD as well, especially as a form of emergency contraception if needed. Again, ask over the phone or in reception regarding the fitting.

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