Key takeaways

• IUDs are over 99% effective at preventing pregnancy.
• Two main types: hormonal (with progestin) and non-hormonal (copper).
• Lasts 3–12 years and is fully reversible.
• Low-maintenance once inserted.
• Insertion is quick; mild cramping is common.
• Side effects vary but are usually manageable.
• Talk to a provider to choose the best option for your needs.

How does an intrauterine device work for birth control?

An intrauterine device (IUD) is a small, flexible device placed in the uterus to prevent pregnancy. It works by changing how sperm moves, making it harder to fertilize an egg. There are two main types: hormonal and copper. The hormonal IUD releases progestin, which thickens cervical mucus and sometimes stops ovulation. The copper IUD releases copper ions that are toxic to sperm.

Choosing an IUD means long-term, low-maintenance birth control, something many people find empowering because it frees you from daily reminders. While IUDs are highly effective, it’s important to talk with a healthcare provider to find the option that fits your individual health and lifestyle.

Understanding how an IUD works is just the first step. Learning about their benefits and possible side effects can help you feel confident and informed as you explore your reproductive health options.

What is an intrauterine device?

An intrauterine device (IUD) is a small, T-shaped birth control device placed inside your uterus. Think of it as a quiet guardian for your reproductive system: small but highly effective at preventing pregnancy.

There are two main types of IUDs: hormonal IUDs and copper IUDs. Each works a little differently, but both offer reliable, reversible birth control that can last for years. The device itself is about the size of a quarter, made from flexible plastic, with thin strings that extend through your cervix into your vagina.

What makes IUDs stand out? They’re over 99% effective, more reliable than the pill, patch, or condoms. After your provider places your IUD, you can mostly forget about it for 3 to 12 years, depending on the type. No daily pills to remember, no weekly patches to change, and no monthly rings to replace.

Types of IUD devices

When it comes to IUDs, you have options, and knowing what each one offers helps you choose what fits your body and lifestyle best. Here’s a quick breakdown of the main types:

Hormonal IUDs release a small amount of the hormone progestin directly into your uterus. These IUDs work by thickening your cervical mucus to block sperm and thinning your uterine lining to reduce the chance of implantation. 

Copper IUDs, like Paragard® here in the US, don’t use hormones at all. This hormone-free option provides up to 12 years of protection. Copper creates an environment that’s toxic to sperm, stopping them before they reach an egg. Paragard® can also be used as emergency contraception if inserted within five days after unprotected sex.

Each has its perks: hormonal IUDs often lighten or stop periods, while copper IUDs keep your natural cycle intact—ideal if you want to avoid hormones.

Size can also be a factor. Skyla® and Kyleena® are slightly smaller than Mirena®, making them good options if you haven’t given birth yet. But don’t worry, all IUDs are safe and effective for anyone with a uterus, no matter your pregnancy history.

How is an IUD placed?

Getting an IUD inserted might feel a bit intimidating, but knowing what to expect can help ease your mind. The whole procedure usually takes about 5–10 minutes in your provider’s office. Yep, it’s that quick!

Here’s how it works:

Your provider will start with a pelvic exam to check the size and position of your uterus. They’ll use a speculum (that duck-bill shaped tool) to see your cervix clearly, then clean it with an antiseptic solution. Next, they’ll guide the IUD through your cervix using a special inserter tube and place it right where it needs to be. Once that’s done, the inserter comes out, and your IUD is in.

You’ll have tiny strings, about 1–2 inches long, that hang down through your cervix into your vagina. Don’t worry—you won’t feel them during daily activities or sex. Your provider will trim them just right so they curl around your cervix comfortably.

Most people describe the insertion as uncomfortable rather than painful—kind of like strong period cramps for a few minutes. Some feel a sharp pinch when the IUD passes through the cervix. Everyone’s experience is different, and both reactions are completely normal.

Afterward, it’s common to have some cramping and spotting for a few days. Your provider will schedule a follow-up visit in a few weeks to check that your IUD is still in place and the strings are where they should be.

Preparing for insertion

Getting ready for your IUD appointment doesn’t take much, but a little prep can make things smoother.

• Timing can help: many providers suggest scheduling insertion during your period when your cervix is naturally more open, and they can be sure you’re not pregnant.
• Take some ibuprofen about an hour before your appointment. This simple step often reduces cramping during and after the procedure.
• Eat a good meal beforehand to avoid feeling lightheaded.
• Wear comfortable clothes and bring a pad or liner—some spotting is normal after insertion.
• If you’re nervous (completely understandable!), bring someone to support you or drive you home. Most people feel fine driving themselves, but having backup is always nice.
• Sometimes, your provider might prescribe misoprostol, a medication to soften your cervix, to take the night before. Not everyone needs it, but it can make insertion easier.
• Be open with your provider about your medical history, including past pregnancies, STIs, or pelvic infections. This helps ensure the safest care possible.

Managing pain and discomfort

IUD insertion can be uncomfortable, but there are ways to manage it.

• Deep breathing and muscle relaxation during the procedure can make a big difference.
• Some providers offer a numbing gel or injection on your cervix—don’t hesitate to ask if that would help.
• The strongest cramping usually happens right when the IUD is placed, then fades within minutes. Think of it like a strong period cramp that quickly eases.
• After insertion, you might feel crampy for a few hours or a couple of days. Keep taking ibuprofen as directed. It’s your best ally for pain and inflammation.
• Heat is another great helper. A heating pad on your lower belly or back can work wonders, and some find warm baths soothing, too.
• Take it easy that day, this is your official pass to binge-watch your favorite shows and order in some comfort food.

If you experience severe pain that doesn’t get better with medication, fever, or heavy bleeding (soaking through a pad every hour), contact your provider right away. These symptoms are rare but need prompt attention.

Most people find that any discomfort is manageable and well worth the peace of mind that comes with years of reliable, low-maintenance birth control.

How the copper IUD prevents pregnancy

The copper IUD is like nature’s own spermicide, no hormones needed. So, how does it work? It’s pretty fascinating. The copper ions released from the device create an environment inside your uterus that sperm simply can’t handle. This turns your uterus into a “no-swim” zone.

Copper intrauterine devices work in a few ways:

• Copper ions are toxic to sperm. They damage the sperm’s tails and heads, making it impossible for them to swim properly or fertilize an egg.
• The copper changes the chemistry of your uterine fluid. This altered environment makes it impossible for sperm to survive the trip to the fallopian tubes.
• Your uterus reacts to the IUD as a foreign object. This causes a mild, safe inflammatory response that sends white blood cells to the area. These cells are great at destroying any sperm that enter, making the uterus an inhospitable place for sperm and any fertilized egg.

What’s especially helpful about the copper IUD is its two-fold action. Not only does it prevent sperm from reaching the egg, but if fertilization does happen, it also prevents implantation. That’s why Paragard® is an excellent option for emergency contraception. It’s actually even more effective than Plan B® when inserted within five days of unprotected sex.

Effectiveness? It’s impressive. Less than 1% of people using a copper IUD get pregnant each year. It’s even more effective than tubal ligation, and completely reversible whenever you’re ready.

How a hormonal IUD prevents pregnancy

Hormonal IUDs take a smart, targeted approach to preventing pregnancy. They release a small amount of a synthetic hormone called levonorgestrel (a type of progestin) directly inside your uterus. 

Here’s how they work:

• Thickening cervical mucus. The hormone thickens your cervical mucus, turning it into a nearly impenetrable barrier. Imagine trying to swim through honey instead of water—that’s what sperm face. This mucus barrier keeps sperm from reaching the egg in your fallopian tubes.
• Thinning the uterine lining. Hormonal IUDs also thin the lining of your uterus (the endometrium), making it a tough environment for a fertilized egg to implant and grow, like trying to plant a seed in concrete.
• Sometimes stopping ovulation. In some cycles, hormonal IUDs can even prevent ovulation, though that’s not their main way of working.

Unlike birth control pills that send hormones throughout your whole body, hormonal IUDs deliver progestin right where it’s needed most. This localized hormone release means you get strong pregnancy protection with fewer systemic side effects. Many people find this gentler on their bodies.

Different brands release different hormone amounts. Mirena® releases about 20 micrograms daily, while Skyla® releases around 14 micrograms, but all hormonal IUDs are over 99% effective.

Hormones and breast cancer risk

Some people worry about hormone use and breast cancer risk. Research indicates hormonal IUDs may slightly increase risk, but the overall chance remains very low. The targeted hormone delivery with IUDs means less hormone circulating through your body compared to other methods.

Benefits of using an IUD

IUDs offer several advantages that make them a popular and reliable choice for birth control:

Highly effective: With less than a 1% failure rate, IUDs are more effective than most other reversible methods like the pill, patch, or ring.

Long-lasting protection: Once inserted, you’re covered for 3 to 12 years, depending on the type. No daily or monthly reminders needed.

“Set it and forget it” convenience: No chance of forgetting a pill or patch means more freedom and spontaneity in your life.

Cost-effective: Though the upfront cost can feel high, spread over years of use, IUDs often cost less than monthly methods. Many insurance plans cover them fully.

Hormone options:

• Copper IUD contains no hormones at all.
• Hormonal IUDs release progestin locally, which is gentler on your body compared to systemic hormones.

Great for special health needs: Safe for people who smoke, have certain health conditions, or are breastfeeding.

Reversible: When you’re ready to conceive, your provider can remove the IUD quickly, with fertility typically returning immediately.

Period benefits: Hormonal IUDs often lighten or stop periods altogether—especially helpful if you have heavy menstrual bleeding.

Risks and side effects

IUDs are very safe for most people, but it’s important to know about potential side effects and risks so you can make the best choice for your body.

Common side effects:

Changes in bleeding: With copper IUDs, periods may become heavier, longer, and crampier, especially in the first few months. Spotting between periods is also common. Hormonal IUDs usually lighten your periods or stop them altogether. However, irregular bleeding or spotting for the first 3 to 6 months is normal as your body adjusts.

Cramping: Many people experience cramping right after insertion and during adjustment. Over-the-counter pain relievers like ibuprofen can help manage this.

Hormonal effects (with hormonal IUDs): Some may notice mood changes, acne, or breast tenderness. These side effects tend to be milder than those from birth control pills because the hormone dose is lower and localized.

Serious but rare risks:

Infection: Risk is highest within the first 20 days after insertion. Your provider will screen for STIs beforehand to minimize this.

Expulsion: The IUD may partially or fully come out in very few cases, usually within the first year.

Uterine perforation: Occurs in less than 1 in 1,000 insertions when the IUD accidentally pokes through the uterine wall, usually during placement.

Ectopic pregnancy: Though rare, if pregnancy occurs with an IUD in place, it’s more likely to be ectopic (outside the uterus) and requires urgent care.

Expulsion and uterine perforation

Expulsion happens in very rare cases, usually within the first year. You might feel the device or notice new period-like symptoms. You’re more at risk if you’ve never been pregnant, have heavy periods, or had your IUD inserted right after childbirth.

Uterine perforation is very rare, occurring in less than 1 in 1,000 insertions, and usually happens during placement. Most heal on their own, but the IUD must be removed.

Checking your IUD strings monthly is important. If you can’t feel them or they feel different, or if you feel the device itself, contact your provider. Most often, strings just shift or curl behind the cervix, but a quick check can give peace of mind.

Bleeding changes and cramps

Copper IUDs often cause heavier, longer periods and more cramping at first. These symptoms usually improve over a few months. Hormonal IUDs tend to cause irregular spotting initially, followed by lighter or no periods over time. Mild cramps are common with hormonal IUDs as well.

Contact your provider if you experience heavy bleeding (soaking through a pad or tampon every hour for several hours), severe cramps that don’t get better with medication, or bleeding after sex. These could be signs that your IUD has shifted or other issues needing attention.

Making confident choices about your birth control

Understanding how an IUD works puts you in control of your reproductive health. Whether you choose a copper IUD that creates an environment hostile to sperm or a hormonal IUD that uses progestin to thicken cervical mucus and thin your uterus lining, you’re choosing one of the most effective and convenient birth control methods available today.

IUDs offer many benefits, from over 99% effectiveness and long-lasting protection to the freedom of not having to think about birth control every day. They fit a variety of lifestyles and bodies, making them a great option for many people. While side effects like irregular bleeding and cramping can happen, they’re usually manageable and temporary.

While an IUD is a great option for many, it still doesn’t suit everyone’s lifestyle or needs. Ready to see what type of birth control is right for you? 

Nurx makes it easy to connect with expert providers from the comfort of home. Get personalized guidance, timely prescriptions, and discreet delivery, so you can confidently choose birth control that fits your life.

Frequently Asked Questions (FAQ)

Where does your period go when you have an IUD?

If your hormonal IUD stops your period, that’s because the hormone prevents your uterine lining from thickening. Without that buildup, there’s no lining to shed—so no period blood to expel.

Can my boyfriend feel my IUD with his fingers?

Most partners won’t feel the IUD strings. They’re soft, flexible, and usually curl up behind the cervix where they’re out of the way.

What are the disadvantages of the IUD?

While IUDs are very safe, risks include a small chance of pelvic infection around the time of insertion, the device moving or coming out, uterine injury during placement, and, in rare cases, ectopic pregnancy if the IUD fails.

Can you still get pregnant with an IUD?

Pregnancy with an IUD is very uncommon, but it can happen if the device isn’t positioned correctly, slips out, or is used beyond its recommended time frame. Regular check-ins with your provider can help you stay protected.

The information provided is not a substitute for professional medical advice, diagnosis, or treatment. You should not rely upon this content for medical advice. If you have any questions or concerns, please talk to a medical professional.