How does opill work?

[Kasi]

So my boyfriend and I had sex today, without a condom, and I still have yet to start my period but took a test and it was negative!
Anyways continuing on.. I started taking opill on Wednesday, I took it at 9:58, and I’ve continued to do so, it’s been 42 hours and opill takes 48 hours to work, obviously my boyfriend said there was no precum which there probably was but that’s okay, I just wanted to know if opill will actually help prevent a pregnancy if it’s only been 42 hours.
I also have a feeling it’s delaying my period, and I obviously have been stressed!

[Sofi]

Hi Kasi!

So, if you just had sex today, a pregnancy test would mean nothing since it's way too soon to tell. Your period also wouldn't be delayed yet if it was supposed to start today, so that's likely a hormonal thing (it's very normal for periods to start at different days every month or just sometimes be late, and it's not as common as you'd think to have a perfect cycle).
To understand better how fertilization and pregnancy work, you can read about it here:
Human Reproduction: A Seafarer's Guide

The opill takes 48 hours to be effective, and they recommend to use a secondary barrier like a condom in those first two days. This doesn't mean you need to panic right away, this is just the timeframe they want people to use but it doesn't mean you're pregnant because it's been only 42 hours. You'll need to wait a few days to see if your period comes and if it hasn't, you can take another test. In the meantime, if you decide to have sex again, you can use a condom for some peace of mind. The opill could delay your period as a side effect, this isn't uncommon with birth control, so keep that in mind too.

Now, I see you've come to us several times before with pregnancy anxiety, so I want to check in on how the resources we've sent in the past have helped. Would you like me to send some again?
Given this history of anxiety around this, I really would suggest not having sex without using protection, as you can see how this only elevates that anxiety. The stress this is causing you is just not worth skipping a condom over. So if you decide to switch to a different birth control, for example, and are off it for a bit -- condoms are your friend. Unprotected sex is going to leave more room for doubts for you, which we don't want. <3