You've almost certainly come across it: that small T-shaped device, around 3 cm long, that sits in the uterus. The coil — usually called an IUD (intrauterine device) or, for the hormonal version, an IUS (intrauterine system) — remains one of the most effective and discreet forms of contraception. In the UK, it's available free on the NHS and is increasingly chosen by younger people, including those who have never been pregnant. And yet, questions still come thick and fast when you talk about it with friends.

Two families, two approaches

There isn't just one coil but two main families, each with its own way of working. The copper coil (IUD) affects sperm so they can't fertilise an egg; depending on the model, it protects for five to ten years. The hormonal coil (IUS) releases a progestogen that thickens cervical mucus and changes the lining of the womb; it lasts from three to eight years depending on the version. Both are more than 99% effective in typical use. So when it comes to reliability, this is a solid option.

One myth to put straight: contrary to an old idea, the coil is not a 'mini-abortion'. It mainly works by preventing fertilisation, not by dislodging an egg that has already implanted. That's a big difference if you're still deciding whether to go ahead.

Two coils on a white dish: one with copper wire, the other in clear plastic
Two families, two ways of working: copper or hormonal

Having it fitted, in practice

It all starts with an appointment. The professional — gynaecologist, sexual health nurse, GP or trained clinician — checks there's no reason you can't have one, measures the uterus, then inserts the device. Fitting takes a few minutes, and it often feels like a sharp cramp, more noticeable if you've never given birth. In practice, what makes all the difference is having someone who explains each step and gives you time to breathe.

Young Latina woman sitting calmly in a bright clinic room, hands resting on her knees
Before fitting, time to talk through your questions

It can be inserted at any point in your cycle, as long as you're certain you're not pregnant. Some clinicians prefer to do it during your period, when the cervix is a little softer.

The days afterwards

After fitting, you may have cramps, pulling sensations or light bleeding. These usually settle fairly quickly. Sex isn't banned, but many clinicians suggest waiting 24 to 48 hours. A check-up is recommended four to six weeks later to make sure the threads are in the right place.

Young woman relaxed on a sofa, wrapped in a throw, a herbal tea in her hands
In the first few days, your body mainly needs calm and gentleness

After that, learn to check your threads at least once a month, and plan an annual check-up. These appointments are there to make sure your uterus is tolerating the device — easy to forget, but worth keeping.

What can cause problems

Spontaneous expulsion can happen: it's more common in the first few months, especially if you've never been pregnant. Periods can become heavier and more painful with a copper coil; the hormonal version often makes them lighter. Bear in mind that every body reacts differently, and what's true for one person may not be true for another.

The risk of a genital infection (uterus, fallopian tubes) is real but rare, especially around the time of fitting if an STI is present. Left untreated, an infection can affect fertility — which is why testing before fitting is worth considering if you have more than one partner.

Product photo inspired by a natural linen hot water bottle - 20 x 40 cm
Linen hot water bottle resting on a bed with rumpled sheets, a glass of water beside it, soft light
For cramps, the gentle warmth of a hot water bottle remains a simple ally

What we know, and what we don't know yet

We know the coil is offered to people who have never been pregnant, and that UK guidance supports its use by people of all ages, including under-20s. What we understand less well is pain: some people describe fitting as easy, others as very uncomfortable. You can ask for a local anaesthetic if you're worried about the procedure, or look for a clinician who offers it.

Young Asian woman writing questions in a notebook at a light table
Write down your questions before the appointment so you don't forget anything

Thinking about a coil? Write down your questions before the appointment: how long you want it for, which type (copper or hormonal), pain relief, and follow-up checks. None of them are silly. And if you have a fever, severe pain, heavy bleeding or unusual discharge after fitting, seek medical advice without delay.

Cost

In the UK, contraception is free on the NHS, including the coil, the consultation, fitting and removal. You don't pay for the device or the appointment if you go to an NHS sexual health clinic, GP surgery or young people's service. This applies whatever your age, including under-16s, and the service is confidential.

If you choose to go private, prices vary by clinic, so ask for a quote before you book. The coil itself and the fitting may be charged separately.

Where to get it: NHS sexual health clinics, GP surgeries, and some young people's services. You can also ask your GP for a referral if they don't fit coils themselves.

So there you have the broad picture. The coil is neither a universal solution nor the scare story it's sometimes made out to be — it's a choice to think through, discuss and decide with your clinician. So if it's been on your mind, book an appointment, ask your questions, and trust yourself.

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