Levonorgestrel emergency contraception works best before ovulation, especially when taken as soon as possible. Its main action is delaying or preventing the release of an egg. If ovulation has already occurred, levonorgestrel is much less likely to help.
How levonorgestrel works
Products such as Victoria OneStep, Postinor-1, My Way, and Plan B One-Step contain levonorgestrel 1.5 mg. They mainly delay the hormonal events that lead to ovulation. They do not terminate an established pregnancy.
When is levonorgestrel most effective?
- Before the LH surge and before ovulation: This is the biological window in which delaying ovulation is most useful.
- As soon as possible after sex: Earlier use gives the pill a better chance to act before ovulation progresses.
- Commonly within 72 hours: Do not wait until the final hour if you already know you need it.
When is levonorgestrel least effective?
It becomes less dependable when ovulation is very close or has already happened. An app cannot confirm ovulation with certainty; cycle predictions can shift. A positive ovulation test suggests an LH surge but still does not give an exact release time.
Why might a 120-hour option be considered?
Mifestad 10 contains low-dose mifepristone and is marketed by StillSafe PH as an emergency-contraception option for use up to 120 hours. Its ingredient and mechanism differ from levonorgestrel, so it should not be treated as simply a stronger brand of Plan B. Individual suitability, pregnancy possibility, medical history, medicines, breastfeeding, and local clinical guidance matter.
Important accuracy point about “during ovulation”
No oral emergency-contraceptive pill should be described as guaranteed after ovulation. If ovulation may already have occurred, speak with a qualified clinician promptly about the most effective emergency-contraception option available to you. A copper IUD, where accessible and medically suitable, is the most effective established method of emergency contraception and also provides ongoing contraception.
How to choose based on timing
- Recent exposure, likely before ovulation: Taking Victoria OneStep promptly may be appropriate.
- More than 72 hours have passed: Ask about a suitable 120-hour option rather than waiting.
- Ovulation timing is uncertain: Do not rely only on an app; request a personalized assessment.
- Repeated sex happened: Give the adviser the time of every incident because later exposures may not be covered by an earlier pill.
After taking emergency contraception
Your next period may come earlier or later. Use condoms for further sex, follow the specific product instructions, and take a pregnancy test around three weeks after the last unprotected exposure. Seek urgent medical care for severe one-sided pain, fainting, or heavy bleeding.
Bottom line
Levonorgestrel is most useful when taken early and before ovulation. When the timeline is longer or ovulation may be close, a different 120-hour strategy may be considered—but “better” depends on the specific situation. Contact StillSafe PH for private timing guidance.
Medical note: This article provides general education and does not replace advice from a licensed clinician. Seek urgent care for severe pain, fainting, heavy bleeding, high fever, or signs of an allergic reaction.