Direct answer first: Plan B (emergency contraception) is most effective the sooner it is taken after unprotected sex, but it can still be used up to 3 days (72 hours) after intercourse in many formulations, and some guidance extends up to 5 days depending on the product. If you are asking for how late you can take it, the safest general guidance is within 72 hours; if you’re within 3–5 days, check the specific product you have, as effectiveness drops with time, and consult a healthcare provider for personalized advice. Details and nuance
- Timing window:
- Levonorgestrel-based EC (Plan B One-Step and similar) is recommended within 72 hours (3 days) of unprotected sex, with earlier use offering better protection. Some sources discuss up to 4–5 days in certain contexts, but effectiveness declines significantly after 72 hours. If in doubt, seek medical guidance promptly.
- How to take it:
- Take the single dose (or the recommended dose if using a multi-pill product) as directed on the package. If you vomit within 2–4 hours after taking the pill, you may need to repeat the dose in many guidelines. Always follow the instructions for your specific product.
- After taking EC:
- EC does not protect against pregnancy from other sexual encounters in the same cycle; use a reliable contraception method going forward and consider a backup method for a short period as advised by guidance. For those on hormonal contraception, resume or continue according to product recommendations after taking EC.
- Effect on your period:
- It’s common for EC to alter the timing of your next period; periods may come earlier or later than usual, and bleeding patterns can be lighter or heavier. If your period is more than a week late or you have other pregnancy concerns, test or consult a clinician.
What to consider next
- If you are past 72 hours but within 5 days and want to explore options, contact a healthcare provider promptly; they may discuss additional EC options (like ulipristal acetate) which have different timing windows and considerations.
- If you had unprotected sex more recently or want ongoing contraception, consider starting or adjusting regular birth control and discuss with a clinician to prevent future pregnancy risks.
If you’d like, share your location (country/region) and the EC product you have (if any), and I can tailor timing, instructions, and next steps based on the local guidance.
