What to Know About the Contraceptive Coil

There are 2 types of contraceptive coils, which work to prevent pregnancy in different ways:

1. The intrauterine device (IUD or copper coil), which is non-hormonal.
2. The intrauterine system (IUS), which is a hormonal coil.

The intrauterine device (IUD) is coated with copper and is also called a ‘copper coil’. An intrauterine device is a non-hormonal coil.

The intrauterine system (IUS) releases the hormone progesterone and is also called the ‘hormonal coil’. Here, we look at the main differences between them and why you might choose one over the other.

How does the copper coil work?

The IUD releases small amounts of copper into your uterus. Sperm is 'killed' by copper, so using the coil means sperm cannot survive for very long in the womb. Copper also changes the cervical mucus at the entrance of the womb to stop sperm from getting in. The tiny amounts of copper released are not toxic and will not cause any harm.

The copper coil (IUD) starts working to prevent pregnancy as soon as it’s inserted, which is why it’s often recommended as a form of emergency contraception, as well as a long-term contraception.

How does the hormonal coil work?

The IUS releases the hormone progesterone, which thins the uterine lining and thickens your cervical mucus, preventing successful fertilisation. Progesterone can also stop your ovaries releasing any eggs (ovulation).

Unlike the copper coil (IUD), the hormonal coil (IUS) only works straight away if inserted on the first 5 days of your period. If it’s fitted at any other time in your cycle, you’ll need to use another form of contraception like condoms for 7 days after to ensure you’re fully protected.

How long does the coil last for?

IUDs can last for 5 to 10 years, and an IUS can last for 3 to 5 years, depending on the brand used.

There are many different brands of IUD available in the UK – your healthcare provider can advise you on the specific device for you. If you want an IUS, 2 brands are available in the UK: Mirena and Jaydess.

If you’re thinking of getting the coil fitted, speak with your GP or another medical professional. They can help you decide if it’s the right option for you. For many people, the benefits of the coil mean it’s a good choice. But it does have certain drawbacks to be aware of too.

If the coil is not right for you, or you’re concerned about the procedure, other methods of contraception are still over 99% effective when taken perfectly, including the contraceptive pill (taken daily) and contraceptive patch (changed weekly).

The coil is over 99% effective at preventing pregnancy. Once an IUD is fitted, it works straight away. An IUS can work immediately but needs to be fitted on days 1 to 5 of your menstrual cycle (the start of your period). If you fit it at any other time, you’ll need to wait 7 days to have sex, or use another method of contraception like condoms for 7 days.

Coils always have ‘perfect use’, which means that once they’re fitted correctly, they’re almost always at maximum effectiveness. The only thing you need to do is regularly check that it’s in place.

In comparison, contraceptives like the pill are less effective in ‘typical use’ than coils. This is because people do not always take them perfectly. The only other contraceptive with perfect use like the coil is the contraceptive implant.

What makes the coil less effective?

The coil would only become less effective if it:

• moves out of place
• comes out
• is not changed on time

There’s a higher risk of your womb forcing the coil out if:

• you’re under 20 years old
• you’ve never been pregnant
• your womb has forced out a coil before
• you have fibroids (growths on the womb)

It’s a good idea to keep a record of when your coil was inserted, so that you know when it is due to be changed.

Deciding between the IUD and the IUS depends on a few factors that you will discuss with the doctor or nurse when you go for the procedure. This will be influenced by your medical history, a doctor’s advice, and your own preference.

Factors to consider include:

• how long you want the coil to be effective for
• whether you’re able to use hormonal contraception
• if you have other conditions that the coil could help with, for example, heavy periods or endometriosis
• if you have any medical reasons why the coil might not be suitable, such as pelvic inflammatory disease, pelvic infections, cervical cancer, recent cases of sepsis, or anatomic abnormalities that might prevent the device from fitting in place
• whether or not you have an allergy to copper

The coil can be used by many women, but there are some situations where it’s not advisable.

Who can use the coil?

You can get the coil if you’re of reproductive age, even if you’re under 16. If you are under 16, you do not need the permission of a parent or carer as long as the doctor or nurse is sure that you fully understand all the information you’ve been given and the choices that you’re making.

Who cannot use the coil?

You cannot get any type of coil fitted if:

• you’re pregnant or you think that you could be pregnant
• you’ve had a baby in the last 4 weeks
• you have a pelvic infection
• you have vaginal inflammation
• you have an STI

Some conditions that affect the womb, like fibroids (growths on the womb), might mean that the coil is less suitable for you. If you have any signs of infection or any unexplained bleeding, these are symptoms that the doctor or nurse will want to look into more before inserting a coil.

You cannot use the IUD if you have:

• a copper allergy
• cancer of the womb or cervical cancer, and it may not be suitable if you have ever had one of these cancers in the past
• a history of liver cancer

The IUD might be less suitable if you have heavy or irregular periods, because it might make these symptoms worse.

You cannot use the IUS if you have:

• allergies to any of the components in the IUS
• breast cancer, cancer of the womb or cervical cancer, and it may not be suitable if you have ever had one of these cancers in the past
• a history of liver cancer

Both types of contraceptive coil are available for free on the NHS (even if you’re under 16).

You can get the coil at:

• GP surgeries
• contraception clinics
• sexual health or GUM (genitourinary medicine) clinics

Whether you can get a coil fitted or not depends on whether the coil is right for you. Your GP or nurse will check this before they recommend you have a coil fitted.

How is the coil fitted?

The procedure for getting the coil fitted lasts about 20 minutes. You will lie on a special bed with supports for your feet. The doctor or nurse will use an instrument called a speculum which allows them to open the vaginal walls and view the cervix. They then use a special device to insert the coil into your uterus.

Does having the coil fitted hurt?

Yes, the reality is that for many people, getting the coil fitted can be painful. In one survey, half of the people who had the coil fitted described it as an intense pain, and almost a third described the pain as moderate. Less than 3% said they did not find the procedure painful.

The doctor or nurse doing the procedure will try to be as careful and quick as possible, but you can expect discomfort. In the hours and days after getting the coil fitted, you’re also likely to continue feeling some discomfort (it might feel like bad period pain), as well as spotting. Taking painkillers like paracetamol or ibuprofen is recommended and can help reduce pain and discomfort.

Side effects can happen with most treatments, but not everyone gets them.

Side effects of the IUD

The most common side effects of the copper coil are heavier and more painful periods. This is even more likely if you normally have heavy and painful periods.

Other side effects are not common but include:

• cramps
• backache
• change in vaginal discharge

Side effects of the IUS

The most common side effects of the hormonal coil include:

• headaches
• feeling sick (nausea)
• mood swings
• any acne you already have getting worse
• breast tenderness
• irregular bleeding

These side effects are most common during the first 3 to 6 months and usually disappear after a few months.

An uncommon side effect of the IUS is ovarian cysts. These are not harmful but can sometimes cause pain. They’ll often disappear on their own without you knowing about them.

How to manage side effects of the coil

If you experience the coil’s side effects, the following tips can help manage them:

• feeling sick – eat small portions of light meals each day, drink plenty of water, and avoid fatty, fried, and strong-smelling foods
• backache, headache, or cramps – if you can take them, try a painkiller like paracetamol to help relieve pain
• mood swings – keep to a regular sleep pattern, make sure you get enough sleep, and speak to your doctor if you’re struggling with your mood and it’s affecting your life
• acne – acne treatments are available from pharmacies or from a doctor if your symptoms are bad or they impact your life
• irregular bleeding – speak to a doctor if you have irregular bleeding that lasts for a long time, or an unusual vaginal discharge

Yes, the coil is regarded as a safe method of contraception. Studies have shown that, for the majority of people who have the coil implanted, it is safe and effective. But it does have a few rare health complications.

Pelvic infection

You should speak to your doctor if you get signs of a possible infection soon after your coil is fitted (most likely in the first 20 days). These signs could include:

• a smelly discharge
• high temperature
• pain just below your stomach

Damage to the womb

In rare cases, fitting the coil can damage your womb by making a small hole in it. The risk is very low if an experienced doctor or nurse is fitting it. This can often cause no symptoms but see your doctor if you get any pain after your coil is fitted.

Ectopic pregnancy

There’s a small risk of an ectopic pregnancy (pregnancy happening outside the womb) if you get pregnant on the coil. It’s possible to get a negative pregnancy test result when you have an ectopic pregnancy.

If you have any of the following symptoms and think you may be pregnant, go to your nearest A&E or call 999:

• a sudden, sharp, intense pain in your stomach
• feeling very dizzy or sick
• fainting
• looking very pale
• a pain in your shoulder tip
• vaginal bleeding that’s different from your normal period, such as being watery or dark brown

Other rare risks of the coil

There are a handful of other rare complications that may come with getting the coil:

• the coil being forced out of your womb or moving out of place
• hormonal complications with the IUS
• changes to bleeding patterns

Are there any myths about the contraceptive coil?

Yes, the coil is one of the most effective methods of contraception, but there are some myths surrounding it:

1. Abortion: The coil does not work by causing abortions. It slows the movement of sperm and prevents fertilisation by releasing copper or the hormone progesterone.
2. Weight gain: There is no evidence that using either the IUD or IUS will affect your weight.
3. It stops working after a while: Coils keep working at the same level until it’s time to change them. The effectiveness does not go down with the number of years a coil is used for as long as it is within its usage window.
4. Infertility: Coils should not affect fertility, and you can get pregnant as soon as your coil is removed. Long-term use of a coil is not related to infertility.
5. Ectopic pregnancy or miscarriage after the coil is removed: The coil does not cause a higher chance of having an ectopic pregnancy or miscarriage after it’s been taken out.
6. Moving or travelling in the body: Coils never travel to any other parts of the body. Your womb may force the coil out soon after it’s fitted, but this is not common.
7. Copper toxicity: The copper in the coil is not released into your bloodstream, and unless you have an allergy to copper, it should not cause any health problems.
8. Other health risks: There’s no evidence that the coil causes cancer, birth defects, or STIs.

What if the coil falls out?

If you think your coil has fallen out, see a doctor or nurse who can check for you and use extra contraception until you are sure the coil is in the correct position.

Signs that your coil might have fallen out include:

• the string being out of place, shorter than usual, or missing
• heavy bleeding
• bad cramps
• unusual or more discharge than normal

Your coil is more likely to fall out if you:

• are still recovering from giving birth
• are a teenager
• have had an abortion in the past

The coil is an effective, safe, and widely used form of contraception. If you are interested in getting the coil, discuss it with your GP or a sexual health clinic. They can then make sure it’s a safe option for you and book you in for the procedure.