How long does Plan B Delay Ovulation For?

I had some great questions asked in a comment left on my article,  “Plan B Works How?”.

The questions were:

What if I took Plan B ONE day before my ovulation date – but then I ovulate after that because Plan B delays ovulation. How long does Plan B delays ovulation for? and how effective is it days after taken?

Here are my answers:

The actual duration of effectiveness of Plan B has not been determined…studies have not provided these results as of yet!

In one study, the pregnancy rate after taking the emergency contraceptive 1, 2, and 3 days after unprotected sex was 0.4, 1.2, and 2.7%, respectively.

It’s fairly obvious from these numbers that Plan B becomes less effective as time goes by.  There has been some evidence that the pill may have some effectiveness even up to 120 hours after unprotected sex, but the efficacy is probably even more reduced than if taken earlier.

In regards to how long Plan B delays ovulation, there’s no solid evidence for that either!  Teva, the manufacturer of Plan B and Plan B One-Step, claims that it prevents ovulation – there’s no delay in there anywhere.  The FDA supports Teva’s claim!

There are resources out there though that say the emergency contraceptive both prevents AND delays ovulation.  In these resources, an exact number of hours or days were not reported.  They mentioned that you may be at risk of pregnancy within the first few days of taking Plan B because of the possible delay in ovulation – I think we can use a few days as a rule of thumb as to how long ovulation is put off!

I know these answers are kind of hazy, but there’s just no solid evidence out there to really nail them down!

Hope this informations helps at least a little bit, but definitely e-mail at with any further questions.  Yes, you can always leave a comment on the article as well!

Oh yes, let’s not forget about our FREE video course, “90 Ways to Save Money on Your Prescription Drugs.”  Get it now by clicking on the link!

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