How well does emergency contraception work?

Emergency contraception is a backup method to birth control. You can use it if you didn't use birth control or your birth control method failed. There are two types. They are IUDs and pills. How well each works is given as a percentage. The closer the percentage is to 100%, the better that option works to prevent pregnancy.

**IUD**
More than 99%
Use within 5 days. It's placed by your doctor.

**Ulipristal pill**
98% to 99%
Use within 5 days. Get it from your doctor (prescription).

**Levonorgestrel pill**
97% to 98%
Use within 3 days. Buy it at a drugstore (no prescription).

Current as of: May 1, 2026

Author: WebMD Ignite Staff
Clinical Review Board
All WebMD Ignite education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

Current as of: May 1, 2026

Author: WebMD Ignite Staff

Clinical Review Board
All WebMD Ignite education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

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