Levonorgestrel IUD: what it treats, how it is used, side effects
Last updated September 3, 2026.
The levonorgestrel IUD is a small T-shaped device placed in the uterus that releases a low daily dose of progestin. Brand names include Mirena and Liletta (up to 8 years), Kyleena (5 years), and Skyla (3 years). It is over 99% effective and fully reversible.
What does it treat?
Its primary job is preventing pregnancy, long-term and maintenance-free. Mirena is also approved to treat heavy menstrual bleeding for up to 5 years in women who choose intrauterine contraception, and doctors commonly use this device class for painful periods, endometriosis pain, and endometrial protection. Many users end up with much lighter periods or none at all.
How do you take it?
You do not take it; a clinician inserts it in an office visit that takes minutes, often with a pain reliever taken beforehand. Cramping during and after placement is normal. You check for the threads monthly after the first months, and the device stays until its replacement year or you want it out, which is also a quick office procedure. It works as soon as it is placed if inserted during the first 7 days of your cycle; otherwise backup contraception covers the first week. No daily pills, no refills.
Side effects to know
- Common: irregular bleeding and spotting for the first 3 to 6 months, then lighter periods or amenorrhea, plus abdominal or pelvic pain, headache, acne, breast tenderness, genital discharge, and ovarian cysts that usually resolve on their own.
- Serious: expulsion (the device slipping out, sometimes unnoticed), uterine perforation during insertion, pelvic inflammatory disease (risk concentrated in the first weeks), and if pregnancy occurs with the device in place, a higher share of those pregnancies are ectopic.
Who should not take it?
Not with current or recent pelvic infection, postpartum or post-abortion infection in the past 3 months, unexplained vaginal bleeding, uterine or cervical cancer, known or suspected breast cancer or other progestin-sensitive cancer, severe liver disease, a uterus whose shape is distorted by fibroids, or current pregnancy. Breastfeeding and recent delivery change insertion timing and perforation risk, so your clinician plans the window.
When is it an emergency?
Call 911 for severe lower abdominal pain with fever, fainting, or heavy bleeding soaking a pad an hour. New severe pelvic pain with a positive pregnancy test needs same-day care for possible ectopic pregnancy, as do missing threads with pain. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
How long does the levonorgestrel IUD last?
By brand: Mirena and Liletta are approved for up to 8 years of pregnancy prevention, Kyleena for 5, and Skyla for 3. Mirena's heavy-period indication runs 5 years. You can have any of them removed earlier at any time, and fertility returns quickly after removal.
Will the IUD stop my period?
For many users, eventually, yes. The typical arc is irregular spotting for 3 to 6 months, then steadily lighter periods, with a large share of Mirena users reaching amenorrhea by a year. That is the hormone thinning the uterine lining, and it is expected, not harmful.
Does insertion hurt?
Most people describe strong cramps during the few minutes of placement and for hours to days after. Taking a pain reliever beforehand helps, and the label notes insertion-time reactions like sweating, dizziness, or fainting in some patients. The cramping fades; the device then asks nothing of you for years.
Can the IUD fall out?
It can, most often in the first months, and sometimes without being noticed, which is why monthly thread checks matter. If the threads feel longer, shorter, or gone, use backup contraception and get checked; an expelled or malpositioned device does not protect.
Does the levonorgestrel IUD have the clot risks of the pill?
The hormone dose is low and acts mostly locally in the uterus, so the systemic profile differs from combined pills. Serious hormone-related events are uncommon, but the device is still avoided with breast cancer or severe liver disease, and anyone with clotting history should review the choice with their clinician.
Can I use it if I have never been pregnant?
Yes. Guidelines support IUDs for people who have never given birth, including teens. The uterus may be smaller, which can make insertion slightly more uncomfortable, but it is not a barrier, and expulsion risk is only modestly higher.