How Plan B One-Step® Works

Plan B One-Step® is a progestin-only emergency contraceptive. Each tablet contains levonorgestrel, a hormone that has been used in birth control pills for several decades, and works in a similar way to help prevent pregnancy.

Plan B One-Step® works primarily by:
  • Preventing ovulation
  • It may also work by:
    • — Possibly preventing fertilization by altering tubal transport of sperm and/or egg
    • — Altering the endometrium, which may inhibit implantation

Plan B One-Step® should be taken as soon as possible within 72 hours (3 days) after intercourse. The sooner it is taken, the better it works.

Plan B One-Step® will not work if a woman is already pregnant and will not affect an existing pregnancy.

It’s important to remind patients that Plan B One-Step® is a backup method of preventing pregnancy and should not be used as regular birth control, because it is not as effective.

Next: Usage Information

Did you know?

54% of unintended pregnancies are due to unprotected sex, and 41% result from inconsistent or incorrect use of birth control.4

Helpful Resources >

Additional information and materials for your patients and staff.

Discussing Plan B One-Step®

Talking to your patients about emergency contraception.