You can usually take Plan B up to 72 hours (3 days) after unprotected sex, but the sooner you take it, the better it works.

Quick Scoop

How late can you take Plan B?

  • Plan B (levonorgestrel emergency contraception) is intended for use within 72 hours (3 days) after unprotected penis‑in‑vagina sex or birth control failure.
  • Its effectiveness is highest in the first 24 hours and drops the longer you wait:
    • Within 24 hours: very high effectiveness (around 95% reported by some manufacturers).
* 24–48 hours: still effective, but a bit lower.

* 48–72 hours: still works for many people, but less effective than earlier.
  • After 72 hours, Plan B is much less reliable and usually not recommended as the first choice , though some sources note it may offer some benefit up to 5 days; at that point, providers usually suggest other methods.

What if it’s already been more than 72 hours?

If it’s been more than 3 days but less than 5 days, a different emergency contraceptive pill called ella (ulipristal acetate) or a copper IUD is often preferred because they can work up to 120 hours (5 days) after unprotected sex.

You’d need to talk to a healthcare professional or clinic urgently for those options.

Important things to know

  • Plan B does not end an existing pregnancy ; it helps prevent ovulation so a pregnancy doesn’t start.
  • It’s available over the counter in most places without a prescription or age proof.
  • Common short‑term side effects can include nausea, a temporary change in your next period’s timing or flow, fatigue, and headache.

If you’re worried right now

  • If you are within 72 hours , take Plan B as soon as you can—waiting until “morning” or “later” only makes it less effective.
  • If it’s between 72 and 120 hours , contact a clinic (like Planned Parenthood or your local sexual health service) and ask specifically about ella or a copper IUD as emergency contraception.
  • If your period is more than about a week late after emergency contraception, take a pregnancy test and/or see a healthcare provider for follow‑up.

This is general information, not personal medical advice. If you’re in a time‑sensitive situation or have health conditions, reach out to a doctor, nurse line, or local clinic as soon as possible.