It works in a similar way to
birth control pills.

Plan B One-Step® is a backup plan that helps prevent pregnancy after unprotected sex or birth control failure. It contains levonorgestrel, the same ingredient found in many birth control pills. It should not affect or terminate an existing pregnancy. The sooner you take Plan B One-Step®, the better it works.

Plan B One-Step® is the only FDA-approved one-pill emergency contraception available over the counter, for consumers 17 and older.*

*Prescription required for consumers under 17.