No. You shouldn't rely on Plan B as a form of contraception. If you need birth control there are many more reliable methods of birth control options available.

That's an interesting question. If you look a few threads up you'll see a thread about how Plan B works. It delays ovulation. I'm not sure how long it delays ovulation, however. You'd have to make sure it delayed ovulation long enough so that any sperm deposited in your gf's body died before ovulation (when the egg is released). Basically you don't want her egg and your sperm to meet. Your sperm can live up to 5 days (I've read some places that say sperm can live up to 7 days) while it's waiting around for ovulation, which is when the egg is released.

So, Plan B would have to delay ovulation for over a week for it to prevent the egg from meeting up with the sperm.

Also, the other way Plan B works is to thicken the mucus surrounding the cervix, which would hinder the sperm from getting to the egg. However, I don't know how long it has that effect, either.

There is also a chance that it could backfire and enhance the chances of your girlfriend getting pregnant, because Plan B is progesterone, and progesterone is the hormone the body uses to maintain the uterine lining so it is optimal for a fertilized egg to implant.


You can call 888-NOT-TO-LATE to ask these and any other questions you may have concerning emergency contraception.

Please note that the purpose of Plan B is to be used in case your primary method of contraception failed, like a condom broke, etc. It is not a primary form of contraception. The side effects are very, very unpleasant, and definitely not something you'd want to experience unless you were indeed facing an emergency situation.

So it would make a hostile environment for sperm?

Yes, it would make the area around the cervix "hostile" if you mean hard to get through because the mucus is thickened.

ha i know i shouldn't rely on Plan B as a method of birth control, my g/f and i were just wondering how long it lasts after she takes it...fyi, we haven't had to use Plan B we were just talking about what it does for some odd reason lol

Ok, so did you get your answer? If you still have questions after you read the replies you've received, just ask.

Considering that plan b has a 'success' rate of something around 89% when taken within the first 2 days of the 'accident' - I'd say it is going to go down drastically as the days progress. So, I'm going to stick with my original answer that it isn't going to be very effective at preventing pregnancy the further away from the day you take it.

Ditto.

It should be used as a one time thing... and only effective for that one time intercourse