Yes, Plan B can make your period late, but usually only by about a week. If your period is more than about 1–2 weeks late after taking Plan B, it is time to take a pregnancy test and/or talk to a doctor.

Quick Scoop

  • Plan B is a high dose of the hormone levonorgestrel , which can temporarily disrupt your normal cycle.
  • Your next bleed may be:
    • A bit earlier or later than usual
    • Lighter or heavier
    • Just some spotting instead of a full period
  • For many people, the period comes within about a week of the expected date, but being up to a week late is common.

How Plan B Affects Your Period

  • Plan B mainly works by delaying ovulation (the release of an egg).
  • That delay in ovulation can shift your whole cycle, which is why your period can come later than usual.
  • Some people see:
    • Spotting 1–2 weeks after taking it
    • A one‑time weird cycle, then back to normal within 1–2 cycles

How Late Is “Normal”?

  • Many sources note that:
    • A delay of up to about 7 days is common and usually still considered a Plan B effect.
* Delays up to around 10 days can still be from the pill, especially if your cycles are already a bit irregular.
  • A delay of 2 weeks or more is less typical from Plan B alone and should prompt a pregnancy test.

When To Take a Pregnancy Test or See a Doctor

Consider a home pregnancy test if:

  1. Your period is more than 1 week late after taking Plan B.
  1. You have pregnancy‑like symptoms (breast tenderness, nausea, unusual fatigue) and still no bleed.
  1. You are unsure where you were in your cycle when you took Plan B (for example, possibly already ovulating).

See a doctor or urgent care if you have:

  • Severe lower belly pain on one side
  • Very heavy bleeding (soaking pads every hour for several hours)
  • Fever, chills, bad headache, or vision changes

These can be signs of something more serious and should be checked.

Forum & Real‑Life Experiences

On forums and Reddit, a lot of people describe:

  • Periods coming a week or more late after Plan B, with pregnancy tests still negative.
  • Some cycles feeling “off” (shorter, longer, more spotting) for a month or two.

Those stories show how individual the response can be, but they cannot replace a test or a clinician if you are worried.

Bottom line: Yes, Plan B can make your period late, usually by up to about a week; if it is more than a week late, take a pregnancy test, and if it is 2 weeks late or you feel unwell, talk to a healthcare professional.

Information gathered from public forums or data available on the internet and portrayed here.