The morning-after pill (Levonorgestrel) works by delaying ovulation and your menstrual cycle.
This information has been reviewed by a registered nurse on staff at The Pregnancy Network.
It may also prevent an egg from implanting in the uterus (Mayo Clinic).
Levonorgestrel is sold by brands like “Plan B One-Step” and “Julie” and is classified as emergency contraception. You may experience spotting after taking the morning-after pill, especially if you are taking a progestin-only birth control pill.
How Not to Use Plan B
The morning-after pill was not designed as a primary form of birth control. Since levonorgestrel is designed to delay ovulation, it can disrupt your menstrual cycle and should not be taken frequently. After taking the morning-after pill, your period may be earlier or delayed. (And if you’re worried about becoming pregnant, waiting an extra week for your period doesn’t do much to ease your mind!)
The manufacturer recommends that it should only be used if you missed birth control pills, or your primary method of contraception failed (for example, a condom broke.)
How long is the morning-after pill effective?
The sooner you take the pill after unprotected sex, the more likely it is to be effective. The pill was not designed to be taken after a 72-hour window. Note: even if taken immediately, there is no guarantee the pill is 100% effective; if you are already pregnant, the pill will not end a pregnancy.
When should I take a pregnancy test after taking Plan B?
Emergency contraception will not prevent fertilization, but may prevent implantation.
If you have taken an emergency contraception, but your period is a week late, you may be pregnant. Schedule your free medical-grade pregnancy test here:
Kacey Minor
Kacey Minor is the Communications Manager at The Pregnancy Network.