Do people know how the 'morning after pill' works?


When I was working in a walk-in clinic yesterday evening, I saw a number of people who needed the ‘morning after pill’ or hormonal emergency contraception (EHC).

From my discussions it was clear people wanting to use it knew very little about how it worked.

So I thought this might be a good topic for discussion here.

There are two types of hormonal emergency contraception; one which has to be taken within three days of unprotected sex, and the other within five days.


Both work in similar ways. They delay the release of the egg from the ovary - ovulation.


This is important because sperm survive in the female reproductive system for up to 7 days!

This means that if you ovulate within 7 days after having unprotected sex then there may be sperm ready to fertilise that egg.
So the longer the release of the egg is delayed, the less likely it is that there are sperm capable of fertilising an egg.

This is one of the reasons why we ask in clinic - “When was your last period?”, as this helps to predict when you are likely to ovulate.

Emergency contraception is a complex topic - let me know if you have specific questions. I’d be happy to help.


Will it work if I've had sex multiple times in 3 days?

Hi @Dr_Paula, does that mean if you are likely to have already ovulated then the morning after pill wont make any difference?

I was once told that the morning after pill wouldn’t work for me by a pharmacist once - I was too shocked to listen or understand why. I thought it just worked…I pretty much had to beg to be given it and took it anyway. But maybe that was why? I do remember being asked loads of questions about hoe regular I was etc…


Hi @dani
Yes, you are right. The emergency contraceptive pill does not work if you have already ovulated.

The problem is, unless you are tracking your cycle, it is difficult to be completely sure that you have definitely ovulated, so the guidance is to give it at anytime in the cycle even if you think the person has already ovulated - just in case.

If there is a high risk that you have already ovulated then it is worth thinking about the emergency IUD. This can be inserted up to 5 days after the earliest predicted date of ovulation.

Thanks for the question.



So does it work if you have already ovulated??