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Can I get pregnant with unprotected sex on the last day of my period even if I'm taking birth control pills?

By Anonymous May 6, 2017 - 8:27pm
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My boyfriend and I had unprotected sex on the last day of my menstrual period and I've been taking the Trinessa birth control pills. I was concerned if I will get pregnant. Should I get the plan b emergency back up pill? Or am I protected from pregnancy with my birth control pill?

Add a Comment4 Comments


Hi, Anon.

Thank you for your message.

If you are taking birth control pills correctly and consistently, then you are protected against pregnancy all the time, including the days you take your placebo pills (period week). There is only about a 1% risk of pregnancy when on the pill and having full intercourse.


May 7, 2017 - 4:15am
(reply to Helena)

Thank you for the confirmation. I needed that badly. Another thing though, does taking allegra D for nasal allergies affect the efficacy of the birth control pills? Do I need to buy the emergency contraceptive pill, plan B step? I have regular cycles usually 30 days and usually bleeds for about 5 days but this time I was only bleeding for 4 days. Could that be because I was stressed out and anxious? I was concerned about it so that's why I was thinking of getting the plan B step but I don't want it to mess up or change my cycle.

May 7, 2017 - 12:28pm
Guide (reply to gypsyQ)


I'm not sure why you feel the need to take plan b. As I explained, as long as you are taking your pills correctly and consistently, you are protected. 1% risk overall is very small.

Check with the pharmacist about the Allegra. I don't think it will interfere, but best to be sure.


May 7, 2017 - 1:26pm
(reply to Helena)

Thank you very much!! I appreciate you replying to my question. I've just learned that Allegra D doesn't affect the efficacy of birth control pills.

May 7, 2017 - 5:52pm
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