A coil contraceptive is a small, T-shaped device placed inside the uterus to prevent pregnancy. It’s one of the most effective forms of birth control available, with over 99% effectiveness for both types. There are two kinds: a copper coil, which uses no hormones, and a hormonal coil, which releases a small amount of progestogen locally. Both last for years, work without any daily effort, and fertility returns almost immediately after removal.
Copper Coil vs. Hormonal Coil
The copper coil is wrapped in a small amount of copper wire. It works by affecting sperm function and movement, preventing sperm from reaching and fertilizing an egg. It contains no hormones at all, which makes it a good option if you want to avoid hormonal side effects or can’t use hormonal methods for medical reasons. The copper coil protects against pregnancy for up to 12 years.
The hormonal coil releases a progestogen called levonorgestrel directly into the uterus. This thickens the cervical mucus so sperm can’t pass through, inhibits sperm survival, and thins the uterine lining. Because the hormone acts locally rather than circulating through your whole body, systemic side effects tend to be milder than with birth control pills or injections. Several hormonal coil brands exist with different lifespans: one lasts up to 8 years, another up to 5 years, and a shorter-acting version up to 3 years.
How Effective It Is
Both types of coil are over 99% effective at preventing pregnancy, and there’s essentially no difference between “typical use” and “perfect use.” That’s because once the device is in place, there’s nothing you need to remember to do. You can’t forget to take it, use it incorrectly, or skip a dose. This makes the coil significantly more reliable in real life than methods like the pill, patch, or condoms, where human error plays a bigger role.
What the Insertion Feels Like
Getting a coil fitted is a short in-office procedure. A clinician first does a pelvic exam to check the position of your uterus, then cleans the cervix and uses a small instrument to hold it steady. A thin rod measures the depth of your uterine cavity, and the device is inserted through the cervix using a slim applicator. The strings attached to the coil are trimmed to about 2 to 3 centimeters so they sit just inside the cervical opening.
The whole process typically takes only a few minutes, though pain during insertion varies widely from person to person. Some people feel mild cramping similar to a period, while others find it intensely uncomfortable. Current U.S. guidelines recommend that clinicians discuss pain management options beforehand and create a plan based on your preference. A local numbing injection near the cervix or a topical numbing gel can help reduce pain during the procedure. Over-the-counter painkillers taken beforehand are commonly suggested, though clinical evidence on their effectiveness for this specific purpose is mixed.
Side Effects of the Copper Coil
The most common change with a copper coil is heavier, longer, and more painful periods, especially in the first few months. Spotting between periods is also normal early on. For most people, these symptoms ease up within three to six months as the body adjusts. If heavy bleeding or cramping persists beyond that window, it’s worth following up with a provider. The copper coil doesn’t cause hormonal side effects like mood changes, acne, or weight fluctuation, since it’s entirely hormone-free.
Side Effects of the Hormonal Coil
The hormonal coil has a very different effect on periods. Because it thins the uterine lining, most people experience lighter periods over time. Some stop getting periods altogether after a few months, which is medically safe and often considered a benefit. In the first three to six months, irregular spotting is common as the body adjusts to the local hormone release.
Some people report hormonal side effects like headaches, breast tenderness, or mood changes, particularly in the first few months. These tend to be less pronounced than with systemic hormonal methods because the progestogen is concentrated in the uterus rather than circulating throughout the bloodstream.
Risks and Complications
Serious complications from coils are uncommon but worth knowing about. The main risks are perforation, expulsion, and infection.
- Perforation occurs when the device pushes through the wall of the uterus during or after insertion. A large study published in The Lancet found the five-year incidence was about 0.29% in people who weren’t recently postpartum. The risk increases significantly if the coil is placed within the first six weeks after giving birth, and breastfeeding raises the risk further.
- Expulsion means the device partially or fully slips out of position. This is most likely in the first few months after insertion. You can check that your coil is in place by feeling for the strings with a clean finger. If you can’t find them, or if you feel the hard plastic of the device itself, contact your provider.
- Infection carries a slightly elevated risk in the first 20 days after insertion, but beyond that initial window, the coil itself doesn’t increase your ongoing risk of pelvic infection. A coil does not protect against sexually transmitted infections.
How Long Each Type Lasts
The copper coil lasts up to 12 years, making it the longest-lasting reversible contraceptive available. Among hormonal coils, the longest-acting version works for up to 8 years, a mid-range option lasts up to 5 years, and a smaller version designed partly with younger or nulliparous users in mind lasts up to 3 years. You can have any coil removed earlier than its expiration if you want to get pregnant or switch methods.
Fertility After Removal
Removing a coil takes just a few minutes and is generally quicker and less uncomfortable than insertion. Your ability to get pregnant returns almost immediately afterward. A 2018 review of studies found that contraceptive use, regardless of type or how many years the device was in place, does not negatively affect fertility or delay conception after removal. You can try to conceive in the very first cycle after having the coil taken out, and your fertility baseline will generally be whatever it was before insertion, adjusted for age.
Who Can Use a Coil
Most people with a uterus can use a coil, including those who haven’t had children. The old belief that coils were only appropriate for people who had already given birth is outdated. The hormonal coil is sometimes preferred by people who want lighter periods or who have heavy menstrual bleeding as a pre-existing issue. The copper coil appeals to people who want long-term, hormone-free contraception or who need emergency contraception, since a copper coil inserted within five days of unprotected sex is over 99% effective at preventing pregnancy.
Coils aren’t suitable for everyone. People with certain uterine abnormalities, active pelvic infections, or unexplained vaginal bleeding may need to consider other options. The copper coil isn’t ideal if you already have very heavy or painful periods, since it can make both worse. Your provider can help determine which type, if either, is the right fit based on your health history and preferences.