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Levonorgestrel emergency contraception

Brand names: Plan B One-Step, Take Action, My Way

Levonorgestrel emergency contraception (Plan B) lowers the chance of pregnancy after unprotected sex or birth control failure.

Brand namesPlan B One-Step, Take Action, My Way
Type of medicineEmergency contraception
Prescription?Over the counter, no age limit
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It works mainly by delaying ovulation. It's not an abortion pill and won't affect an existing pregnancy.

It works best the sooner it's taken, within 72 hours. It may work less well in people with higher body weight; ask a pharmacist about ulipristal (ella) or a copper IUD.

What it's used for

  • Preventing pregnancy after unprotected sex, a broken condom, or missed birth control pills

How to take it

  • Take one tablet as soon as possible, within 72 hours of unprotected sex.
  • If you vomit within 2 hours, ask a pharmacist about taking another dose.
  • Take a pregnancy test if your period is more than a week late.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Changes in your next period (earlier, later, heavier, or lighter)
  • Nausea
  • Tiredness
  • Headache
  • Spotting
Call 911Severe lower belly pain 3 to 5 weeks later (possible ectopic pregnancy)

Warnings

  • It doesn't protect against STIs.
  • It's not meant as regular birth control.

Other medicines, foods, and alcohol

  • Rifampin, some seizure medicines, St. John's wort, and some HIV medicines make it less effective; a copper IUD may be better.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

It won't harm an existing pregnancy, but it won't end it either. It's fine while breastfeeding.

Missed doses, overdose, and storage

If you miss a dose

Not applicable: it's a single dose.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.