Coils: the copper IUD and hormonal IUS

Copper and hormonal coils both sit inside the womb. Copper can make periods heavier or more painful. A hormonal coil can make them lighter or shorter, or stop them altogether. That difference may matter to you as much 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. A copper device releases copper and has no hormones. A hormonal device releases progestogen, which US information calls progestin.

NHS guidance says both are over 99% effective. Copper stops sperm from moving well and from fertilising an egg. Hormonal coils thicken the mucus at the cervix (the opening of the womb), hold back sperm and thin the womb lining. Neither protects against STIs, but condoms can.

How long a coil lasts

For contraception, the NHS says a copper IUD lasts 5 or 10 years and a hormonal IUS 3 to 8 years, depending on the type. CDC says copper coils can be used for up to 10 years and hormonal ones for 3 to 8 years. WHO gives a range for copper of up to 10–12 years, because products differ. Advice varies between countries, so check your device’s name and replacement date with your clinic.

A hormonal coil used as part of HRT (hormone replacement therapy) has its own replacement timing. The NHS says it needs replacing every 5 years when used this way. Don’t assume the contraception time limit applies to its use with HRT. Ask your prescriber to confirm the date.

The copper IUD can also be used as emergency contraception. After unprotected sex, or if your contraception failed, ask a pharmacist or contraception service about your options straight away.

Fitting and pain relief

A trained doctor or nurse fits the coil through the cervix into the womb. They use a speculum, a smooth tool that gently opens the vagina. Before fitting, you may be offered tests for pregnancy and STIs. Most people feel some pain during fitting. Talk about pain relief beforehand, including whether a local anaesthetic (numbing medicine) is available.

You can ask the person fitting it to stop at any time. You can also ask for a friend, family member or another member of staff to be with you. Before it starts, tell the clinician what would help.

After fitting, you may have pain like period pain and some spotting. With a copper coil, heavier or more painful periods may get better after a few months. With a hormonal coil, bleeding may last longer, be irregular or come more often at first. Over time it can settle, then get lighter or stop.

Checking threads and planning removal

The coil has soft threads that hang into the top of the vagina. The clinician will show you how to feel them. NHS guidance says to check a few times in the first month and then regularly, for example after each period.

Get advice straight away if you can’t feel the threads or they feel different. Use another form of contraception until a clinician checks the coil. It may have moved, and you may need emergency contraception. If you have a hormonal coil, ask which emergency option suits you, because the coil can affect some types.

You can ask a trained clinician to take a coil out before its replacement date. Fertility comes back straight away after removal. If you want to avoid pregnancy, sort out your next method before the removal appointment, not afterwards.

When to contact a clinician

Rare problems include infection, the coil coming out, and damage to the womb during fitting. The NHS also lists ectopic pregnancy (a pregnancy outside the womb) if a coil fails. Get symptoms checked rather than assuming the coil is the cause.

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 you could be pregnant and you have pain low in your tummy mainly on one side, or pain at the tip of your shoulder. Do this 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 the coil threads are missing or feel different, or you think you may be pregnant. Do the same if you have a fever, smelly discharge, very heavy bleeding, or pain low in your tummy that won’t go away, is getting worse, or isn’t eased by painkillers.

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