There are five IUDs available in the United States, and they fall into two categories: one copper (hormone-free) device and four hormonal devices that release a small amount of progestin. All five are more than 99% effective at preventing pregnancy with perfect use, but they differ in how long they last, how they affect your period, and how much hormone they release.
The Two Categories: Copper vs. Hormonal
Every IUD is a small, T-shaped device placed inside the uterus, but the way each one prevents pregnancy depends on which category it belongs to. The copper IUD contains no hormones at all. Instead, copper ions continuously release into the uterus, creating an environment that interferes with sperm movement and survival. Sperm either can’t reach the egg or can’t fertilize it.
Hormonal IUDs take a different approach. They release levonorgestrel, a synthetic form of progesterone, directly into the uterus. This thickens the cervical mucus so sperm can’t enter, thins the uterine lining, and impairs sperm movement. Because the hormone acts locally rather than circulating through your entire body, the systemic dose is far lower than what you’d get from a birth control pill.
Paragard: The Copper IUD
Paragard is the only non-hormonal IUD on the U.S. market. It’s approved for up to 10 years of use, making it one of the longest-lasting reversible contraceptives available. In clinical studies, fewer than 1 in 100 women became pregnant per year while using it. The typical-use failure rate is 0.8%, and with perfect use it drops to 0.6%.
The biggest draw of Paragard is that it’s completely hormone-free, which matters if you’ve had side effects from hormonal birth control or simply prefer to avoid added hormones. It also works as emergency contraception if inserted within five days of unprotected sex. The trade-off is your period: some people experience heavier-than-usual bleeding and more cramping, particularly during the first year. Unlike hormonal IUDs, Paragard won’t lighten your periods or make them disappear.
The Four Hormonal IUDs
All four hormonal IUDs release levonorgestrel, but they differ in how much hormone they contain, how quickly they release it, and how long they’re approved to stay in place. The typical-use failure rate for hormonal IUDs as a class is just 0.2%, making them slightly more effective than the copper option.
Mirena
Mirena is the original hormonal IUD and has the longest track record. It contains 52 mg of levonorgestrel and starts by releasing about 20 micrograms per day, gradually tapering to around 10 micrograms after five years. Mirena is FDA-approved for up to 8 years of contraception. It’s also approved to treat heavy menstrual bleeding, which makes it a dual-purpose option for people dealing with especially heavy periods.
Liletta
Liletta is very similar to Mirena in size and hormone load, also containing 52 mg of levonorgestrel. It releases about 18.6 micrograms per day initially, decreasing to around 12.6 micrograms by year three. Liletta is FDA-approved for up to 8 years. It was designed to be a more affordable option, and many public health clinics stock it for that reason.
Kyleena
Kyleena is a step down in hormone content, carrying 19.5 mg of levonorgestrel. It releases roughly 17.5 micrograms per day at first, dropping to about 7.4 micrograms after five years. It’s approved for up to 5 years. Kyleena is physically smaller than Mirena or Liletta, which can make insertion more comfortable for people who haven’t been pregnant or who have a smaller uterus.
Skyla
Skyla has the lowest hormone content of any IUD on the market, with 13.5 mg of levonorgestrel. It releases about 14 micrograms per day initially, falling to around 5 micrograms after three years. It’s the shortest-lasting option, approved for up to 3 years. Like Kyleena, it’s smaller in size, and it was specifically studied in women who had never given birth.
How Each Type Affects Your Period
This is one of the most practical differences between the two categories. Hormonal IUDs tend to make periods lighter over time, and many users eventually stop getting a period altogether. Within the first year of using Mirena or Liletta, about 2 in 10 people stop menstruating entirely. The higher the hormone dose, the more likely this is to happen, which is why it’s more common with Mirena and Liletta than with Kyleena or Skyla. The first three to six months can be unpredictable, though, with irregular spotting, light bleeding, and occasional cramping as your body adjusts.
The copper IUD does the opposite. Because it contains no hormones, it doesn’t suppress your natural cycle. Many people notice heavier periods and stronger cramps, especially in the first year. For most, this settles down over time, but your period won’t become lighter than it was before insertion.
How IUDs Compare to Other Contraceptives
IUDs sit near the top of the effectiveness scale. With typical use, the birth control pill, patch, and ring each have an 8% failure rate, meaning about 8 in 100 users get pregnant in a year. The three-month injectable drops to 3%. By comparison, the copper IUD’s typical-use failure rate is 0.8% and hormonal IUDs come in at 0.2%. The only method slightly more effective is the arm implant, at 0.05%. Male and female sterilization fall in the same general range as IUDs, at 0.15% and 0.5% respectively.
The reason IUDs perform so well in real-world use is simple: once one is in place, there’s nothing to remember. You can’t forget to take it, use it incorrectly, or skip a dose. That’s why the gap between “perfect use” and “typical use” is almost nonexistent for IUDs, while it’s enormous for methods like the pill.
Choosing Between Them
The right IUD depends on what matters most to you. If avoiding hormones is a priority, Paragard is your only IUD option, and it lasts the longest at 10 years. If lighter periods (or no periods) sound appealing, a hormonal IUD is the better fit, with Mirena and Liletta offering the strongest effect on bleeding because of their higher hormone content.
Duration matters too. If you want the longest-lasting hormonal option, Mirena and Liletta are both approved for 8 years. If you’re looking at a shorter commitment, maybe because you’re planning a pregnancy in a few years, Skyla’s 3-year window might suit you better. All IUDs can be removed at any time, and fertility returns quickly after removal regardless of which type you had.
Cost can also play a role. Liletta was developed as a lower-cost alternative to Mirena and is widely available through publicly funded clinics. Most insurance plans cover IUDs with no out-of-pocket cost under the Affordable Care Act, but if you’re paying without insurance, it’s worth asking your provider which brands they stock and what the pricing looks like.
Physical size may matter if you have a smaller uterus or have never been pregnant. Kyleena and Skyla are both smaller than Mirena, Liletta, and Paragard, which can translate to a more comfortable insertion. That said, all five IUDs are safe and effective in people who haven’t given birth.