What are the Signs that the Plan B Pill Didn’t Work?

Identifying whether the Plan B pill was effective requires monitoring your body’s response and understanding the timeline of hormonal changes. Because Plan B works by delaying ovulation, it commonly disrupts your menstrual cycle and causes temporary side effects that can mimic early pregnancy.

Key signs that Plan B may not have worked include:

• A period that is more than two weeks late: While Plan B frequently causes a late period (often delayed by 3 to 7 days), a delay beyond two weeks is a primary indicator to seek testing.
• Persistent pregnancy symptoms: Symptoms such as ongoing nausea, breast tenderness, or fatigue that continue or intensify beyond the first week may indicate pregnancy rather than medication side effects.
• Unusual bleeding patterns: While spotting is a common side effect, any bleeding that differs significantly from your normal cycle should be monitored.

Practical Monitoring Steps:

• Take a pregnancy test: For the most accurate results, wait until three weeks after taking Plan B or whenever your period is more than one week late.
• Track your symptoms: Use a journal to note the duration of side effects. Typical Plan B reactions like nausea and fatigue usually resolve within 1 to 2 days.
• Verify timing: Plan B is most effective (up to 95%) when taken within 24 hours. Its efficacy drops to approximately 75% if taken between 49 and 72 hours after unprotected sex.