Coils: the copper IUD and hormonal IUS

Copper and hormonal coils both sit in the womb. Copper can make periods heavier or more painful, while a hormonal coil can make them lighter, shorter or stop altogether. That difference may matter as much to you as how long the coil lasts.

What IUD and IUS mean

In NHS information, IUD usually means the copper coil and IUS means the hormonal coil. US and WHO information uses IUD for both types. A copper device releases copper without hormones. A hormonal device releases progestogen, called progestin in US information.

Both are over 99% effective in NHS guidance. Copper interferes with sperm movement and fertilisation. Hormonal coils thicken cervical mucus, inhibit sperm and thin the womb lining. Neither protects against STIs; condoms can provide that protection.

How long a coil lasts

For contraception, the NHS gives 5 or 10 years for a copper IUD and 3 to 8 years for a hormonal IUS, depending on the type. CDC describes copper use for up to 10 years and hormonal devices for 3 to 8 years. WHO’s international copper range is up to 10–12 years, reflecting different products. Advice differs between countries; check your device name and replacement date with your clinic.

A hormonal coil used as part of HRT has its own replacement timing. The NHS says it needs replacing every 5 years for that purpose. Do not assume the contraception lifespan applies to its use with HRT; ask the prescriber to confirm the date.

The copper IUD can also be used for emergency contraception. Ask a pharmacist or contraceptive service promptly after unprotected sex or a contraceptive failure about the available options.

Fitting and pain relief

A trained doctor or nurse fits the coil through the cervix into the womb, using a speculum to open the vagina. Before fitting, you may be offered pregnancy and STI tests. Most people have some pain during fitting, so discuss pain relief beforehand, including whether local anaesthesia is available.

You can ask the person fitting it to stop at any time. You can also ask to have a friend, family member or another member of staff present. Tell the clinician what would help before the procedure begins.

After fitting, period-like pain and spotting can occur. Heavier or more painful periods with a copper coil may improve after a few months. With a hormonal coil, bleeding may last longer, be irregular or happen more often at first. Over time, it can settle and become lighter or stop.

Checking threads and planning removal

The coil has soft threads that reach into the top of the vagina. The clinician will teach you how to feel them. NHS guidance advises checking a few times in the first month and then regularly, such as after each period.

Get advice straight away if the threads cannot be felt or feel different. Use another form of contraception until a clinician checks the coil, because it may no longer be in place and emergency contraception may be needed. For a hormonal coil, ask which emergency option is suitable, as it can affect some types.

You can ask a trained clinician to remove a coil before its replacement date. Fertility returns straight away after removal. If you want to avoid pregnancy, discuss contraception before the removal appointment rather than waiting until afterwards.

When to contact a clinician

Rare complications include infection, the device coming out and damage to the womb during fitting. The NHS also lists ectopic pregnancy if a coil fails. Get symptoms checked rather than assuming the coil explains them.

Call 999 now (UK), or your local emergency number (US and elsewhere), for sudden intense tummy pain with marked dizziness, fainting or collapse.

Contact an urgent GP service or NHS 111 now (UK), or urgent medical care (US and elsewhere), if pregnancy is possible and you have lower tummy pain mainly on one side or shoulder-tip pain, even without a positive pregnancy test.

Contact an urgent GP service or NHS 111 today (UK), or your doctor or urgent care service (US and elsewhere), if coil threads are missing or feel different, you think you may be pregnant, or you have fever, smelly discharge, very heavy bleeding, or lower tummy pain that is persistent, worsening, or not relieved by painkillers.

Book an appointment with your GP or sexual health clinic (UK), or your doctor or contraceptive service (US and elsewhere), if hormonal-coil side effects bother you.