Levonorgestrel: What It Is, How It Works, and What You Need to Know

When you hear levonorgestrel, a synthetic hormone used in birth control and emergency contraception. Also known as LNG, it's one of the most common progestins used in women's health. Unlike estrogen-based pills, levonorgestrel works alone—making it safer for many people, including those who can’t take estrogen. It’s the active ingredient in Plan B One-Step, Next Choice, and the hormonal IUDs like Mirena and Kyleena. You won’t find it in a pharmacy aisle unless you’re looking for emergency contraception or a long-term birth control device.

Levonorgestrel doesn’t cause an abortion. It prevents pregnancy by stopping or delaying ovulation, thickening cervical mucus to block sperm, and sometimes thinning the uterine lining so a fertilized egg can’t attach. The timing matters: for emergency use, it’s most effective within 72 hours after unprotected sex, though it can work up to 120 hours. The IUD version, inserted by a provider, works for up to five years and is over 99% effective—making it one of the most reliable birth control methods available. It’s also used off-label for heavy periods, endometriosis, and even acne in some cases.

People often confuse levonorgestrel with other hormones like ulipristal acetate (ella) or copper IUDs. Ulipristal works differently and stays effective longer, but levonorgestrel is cheaper, easier to get without a prescription in many places, and has more real-world safety data. The copper IUD doesn’t use hormones at all—it works by creating an inflammatory response that kills sperm. So if you’re looking for a non-hormonal option, copper is the way to go. But if you want a quick, hormone-based solution, levonorgestrel is your go-to.

Side effects are usually mild: spotting, nausea, headaches, or breast tenderness. Some people feel dizzy or get cramps after using it, especially with the IUD. It doesn’t protect against STIs, and it won’t work if you’re already pregnant. And while it’s safe for most, people with liver disease, certain cancers, or unexplained vaginal bleeding should talk to a doctor first. It’s not a daily pill unless it’s part of a continuous regimen—most emergency versions are single-dose.

What you’ll find in the posts below isn’t just a list of products. It’s a practical guide to how levonorgestrel fits into real-life choices—whether you’re weighing emergency options, considering an IUD, or comparing it to other hormonal treatments. You’ll see how it stacks up against alternatives, what the real costs are, and how to use it safely without surprises. This isn’t theory. It’s what people actually use, struggle with, and need to understand.