A hormonal IUD is a small, T-shaped device placed inside the uterus that releases a low dose of synthetic progesterone to prevent pregnancy. It’s one of the most effective contraceptive methods available, with over 99% effectiveness in both typical and perfect use. That puts it on par with the contraceptive implant and well ahead of the pill, patch, ring, and condoms, all of which have significantly higher real-world failure rates.
How a Hormonal IUD Prevents Pregnancy
The device slowly releases a hormone called levonorgestrel directly into the uterus. This does three things: it thickens the mucus at the opening of the cervix so sperm can’t easily pass through, it thins the lining of the uterus so a fertilized egg is unlikely to implant, and it can partially suppress ovulation in some users. Because the hormone is released locally rather than circulating through your entire body first, the amount that reaches your bloodstream is lower than with pills, patches, or other hormonal methods.
Available Brands and How They Differ
Four hormonal IUDs are currently FDA-approved in the United States, and they fall into two size categories.
- Mirena and Liletta are the larger options (32mm x 32mm), each containing 52 mg of levonorgestrel. Liletta is approved for up to 8 years of pregnancy prevention, making it the longest-lasting hormonal IUD on the market.
- Kyleena contains 19.5 mg and Skyla contains 13.5 mg. Both are slightly smaller (28mm x 30mm), which can make them a better fit for people with a smaller uterus or those who haven’t been pregnant before.
The higher-dose devices tend to have a more pronounced effect on periods, while the lower-dose ones release less hormone overall but are approved for shorter durations.
What Happens to Your Period
Lighter periods are one of the most noticeable effects. In clinical data, the higher-dose IUDs reduced menstrual blood loss by up to 90% in people with heavy bleeding. About 2 out of 10 Mirena users stop having periods entirely within the first year.
In the first three to six months, though, many users experience irregular spotting or breakthrough bleeding. This is the adjustment period while the uterine lining thins out. It’s common and typically resolves on its own. For people who’ve been dealing with heavy or painful periods, the hormonal IUD is actually used as a treatment, not just a side benefit. Liletta is specifically FDA-approved for managing heavy menstrual bleeding for up to 5 years.
The Insertion Process
Getting a hormonal IUD placed takes only a few minutes. A clinician inserts the folded device through the cervix and into the uterus, where the arms of the T spring open. Most people feel cramping during insertion, ranging from mild to intense, and the sensation usually lasts less than a minute.
Pain management options exist. A local anesthetic (lidocaine applied as a paracervical block or topically) can help reduce discomfort. The CDC notes that a cervical-softening medication called misoprostol isn’t recommended for routine use, though it may be helpful if a previous insertion attempt failed. Over-the-counter pain relievers taken beforehand can also take the edge off cramping. Current guidelines emphasize that you should be able to discuss pain management options with your provider ahead of time and make a plan based on your preferences.
Cramping and spotting in the hours and days after insertion are normal. Most people return to regular activities the same day or the next.
How It Compares to Other Methods
The gap between the hormonal IUD and user-dependent methods is striking. The combined pill, patch, and vaginal ring all drop to about 91% effectiveness with typical use because people miss doses, change patches late, or forget to replace the ring on time. Condoms sit at 82%. The hormonal IUD stays above 99% because once it’s in, there’s nothing to remember.
Compared to the copper IUD, the hormonal version has a key tradeoff: it releases a small amount of hormone (which some people prefer to avoid), but it tends to make periods lighter rather than heavier. Copper IUDs are hormone-free but commonly increase menstrual flow and cramping, especially in the first several months.
Systemic Hormonal Effects
Because the levonorgestrel acts primarily inside the uterus, the systemic hormone exposure is meaningfully lower than with oral contraceptives. Still, it’s not zero. Some users do report side effects like headaches, acne, breast tenderness, or mood changes. These tend to be milder than what people experience on the pill, and they often improve after the first few months as the body adjusts. The lower-dose devices (Kyleena and Skyla) release even less hormone into the bloodstream, which may matter if you’re particularly sensitive.
Risks and Complications
Serious complications are rare but worth knowing about. The two main risks are expulsion (the device partially or fully slipping out of place) and perforation (the device pushing through the uterine wall).
A large study published in The Lancet found the overall rate of uterine perforation was 0.21% at one year and 0.61% at five years. The risk was higher for people who had the IUD placed in the postpartum period: 0.52% at one year and 1.37% at five years, with breastfeeding further increasing the likelihood. Perforation sometimes requires a minor surgical procedure to retrieve the device, but many cases are identified and managed without major complications.
Expulsion is more common, occurring in roughly 3 to 5% of users within the first year. You can check that your IUD is still in place by feeling for the strings at the top of the vagina. If you can’t find them, or if you feel the hard plastic of the device itself, contact your provider.
Infection risk is slightly elevated in the first 20 days after insertion but returns to baseline after that. The IUD itself does not increase long-term infection risk.
Fertility After Removal
Fertility returns almost immediately after a hormonal IUD is removed. The removal itself takes just a couple of minutes. Unlike the injection, which can delay the return of ovulation for months, the IUD’s local hormone delivery means your reproductive system bounces back quickly once the device is out.
In a review of nearly 15,000 women who stopped various forms of contraception, 83% became pregnant within the first 12 months. For people under 35, the general expectation is about a 20% chance of conceiving each cycle, with 60% pregnant by six months and 85 to 90% by one year. These numbers are essentially the same as baseline fertility rates, meaning the IUD doesn’t appear to cause any lasting delay.
Who It Works Well For
The hormonal IUD is a strong option for people who want long-term, low-maintenance contraception without daily effort. It’s particularly useful for those dealing with heavy or painful periods, since the lighter bleeding is a genuine therapeutic benefit rather than just a side effect. It also works for people who can’t take estrogen (due to migraine with aura, blood clot history, or other reasons), because it contains only a progestin. And because the hormone levels in the bloodstream stay low, it’s sometimes better tolerated than systemic hormonal methods by people who are sensitive to hormonal side effects.