How long before you can have sex without a condom but on birth control?

[clvmsy]

Hi I just started my birth control two weeks ago and a couple days ago I had sex without a condom. I was told by my doctor that I could take the pill when I was on my period so I did but I also wait a couple weeks. I wasn’t concerned at all (I’ve been taking it every day at the same time for two weeks.) but after talking to friends who were on birth control, they all kind of scared me, saying I should have waited a month or two before having sex without a condom. I have one more day to take a Plan B but I’m not even sure if that’s necessary. What do you think?

[al]

Hi there clvmsy,

The relative effectiveness of the pill when first starting it varies a little from person to person (and from pill to pill), but it's usually said to reach full effectiveness at around 7 days of consistent use (more on that here: Birth Control Bingo: The Pill). However, we usually make the recommendation to users starting birth control for the first tiem that they wait a full cycle before going without condoms, just to be safe.
The likelihood of pregnancy depends on what that sex without a condom was like, but you can rest assured that with more than a week's worth of hormones already in your system, the chances of pregnancy were definitely lower than if you had condomless sex with no birth control pills at all. For more info on relative pregnancy risk, see Can I Get Pregnant or Pass On an STI From That?.