IUDs are one of the safest and most effective forms of birth control available. They’re used by millions of people worldwide, and serious complications are rare, occurring in less than 1% of users. That said, “safe” means different things to different people, so it’s worth understanding what the actual risks look like in real numbers.
How Effective IUDs Are
IUDs are more than 99% effective at preventing pregnancy, meaning fewer than 1 in 100 users will become pregnant in a given year. That makes them one of the most reliable contraceptive options, on par with surgical sterilization but fully reversible. Unlike the pill or condoms, there’s no daily action required and no room for user error once the device is placed.
Both the copper IUD and hormonal IUDs share this high effectiveness rate. The copper and certain hormonal IUDs can also double as emergency contraception: if placed within 120 hours (5 days) of unprotected sex, they’re more than 99.9% effective at preventing pregnancy.
Risks During Insertion
The insertion procedure itself is quick, usually taking only a few minutes, but it can be uncomfortable. The most common reaction is a vasovagal response, that lightheaded, nauseous feeling your body produces in response to pain or stress. In one study of 545 insertions, actual fainting occurred in only 0.2% of cases. A temporary drop in heart rate happened in about 1.8% of insertions, and was far more common in people who had never given birth (8.7%) compared to those who had (0.2%).
Uterine perforation, where the device pokes through the uterine wall, is the most serious insertion risk. It occurs in less than 1% of procedures regardless of the type of IUD. When it does happen, it typically requires the device to be removed, sometimes surgically, but long-term damage is uncommon. Current clinical guidelines call for a physical exam before placement to assess uterine size and position, which helps reduce this risk.
Pain management has improved. Updated 2024 guidelines note that a local anesthetic (like a numbing injection near the cervix or a topical gel) can be used during placement to reduce discomfort. Routine antibiotics before insertion aren’t necessary.
Infection Risk Is Mostly Short-Term
One of the oldest concerns about IUDs is pelvic inflammatory disease, a serious infection of the reproductive organs. The data shows this risk is real but concentrated in a narrow window. The highest risk occurs in the first month after insertion, when the relative risk is about 3.8 times higher than for someone using no contraception. After the first four months, the elevated risk largely disappears.
This early spike is linked to bacteria being introduced during the insertion process, not to the device itself. If you have an existing, untreated infection like chlamydia or gonorrhea at the time of insertion, the risk goes up. That’s why providers screen for sexually transmitted infections. If screening hasn’t been done recently, current guidelines say it can happen at the same appointment as insertion, and placement shouldn’t be delayed while waiting for results.
Expulsion: When the IUD Moves
Sometimes the body pushes the IUD out on its own. This is called expulsion, and it’s the most common complication over time. A large study tracking over 5,400 IUD users found that about 10 out of every 100 experienced an expulsion within three years. Rates were similar for both the copper IUD (10.7 per 100) and the hormonal IUD (10.1 per 100).
Expulsion doesn’t cause lasting harm, but it does leave you unprotected against pregnancy, sometimes without realizing it. You might notice heavier bleeding, cramping, or feel the device lower in your vaginal canal. Interestingly, younger age and never having been pregnant, which were long assumed to increase expulsion risk, didn’t consistently hold up as risk factors in the research. No routine follow-up visit is required after insertion, but you should contact your provider if something feels off.
Ectopic Pregnancy Risk Is Lower, Not Higher
A persistent misconception is that IUDs increase the risk of ectopic pregnancy, where a fertilized egg implants outside the uterus. The reality is the opposite. Because IUDs are so effective at preventing pregnancy in general, they dramatically reduce the overall chance of any pregnancy, including ectopic ones.
The numbers are striking. Among people using no contraception or only condoms, the ectopic pregnancy rate was 6.9 per 1,000 women per year. For hormonal IUD users, it dropped to 0.5 per 1,000. For copper IUD users, it was 0.46 per 1,000. That’s roughly a 92 to 94% reduction in ectopic pregnancy risk compared to using no method at all.
Who Shouldn’t Use an IUD
IUDs are safe for the vast majority of people, including teenagers and those who have never been pregnant. But certain conditions make them a poor choice. The CDC classifies the following as situations where an IUD poses an unacceptable health risk:
- Current pregnancy, due to the risk of serious pelvic infection
- Active pelvic inflammatory disease or an untreated STI like gonorrhea or chlamydia
- Unexplained vaginal bleeding that hasn’t been evaluated
- Cervical or endometrial cancer awaiting treatment
- A uterine shape that physically can’t accommodate the device
- Postpartum or post-abortion infection (sepsis)
- Pelvic tuberculosis
Outside of these specific scenarios, most people are candidates for an IUD. Conditions like obesity, diabetes, high blood pressure, and a history of blood clots, which can limit options like the combination pill, are generally not barriers to IUD use.
Fertility Returns Quickly After Removal
If you’re wondering whether an IUD could affect your ability to get pregnant later, the evidence is reassuring. Fertility returns almost immediately after removal, regardless of how long the device was in place. You can try to conceive the very first month.
A 2018 review of nearly 15,000 women found that contraceptive use, including IUDs, doesn’t negatively affect the ability to conceive or delay fertility. Among IUD users specifically, 83% became pregnant within 12 months of removal, a rate consistent with the general population trying to conceive.
Hormonal vs. Copper: Do the Risks Differ?
The two types of IUDs carry similar rates of the major complications: perforation, expulsion, and infection risk are comparable. Where they diverge is in side effects rather than safety concerns. Hormonal IUDs often reduce menstrual bleeding and cramping over time, and some users stop getting periods entirely. The copper IUD contains no hormones but commonly causes heavier, crampier periods, especially in the first few months.
The copper IUD is the only non-hormonal option, which matters for people who experience mood changes, headaches, or other hormone-related side effects. Both types last for years: the copper IUD is approved for up to 10 years, while hormonal IUDs last between 3 and 8 years depending on the brand. Neither type requires ongoing maintenance or refills, which is part of why they’re among the most cost-effective contraceptives over time.