Ask the Doctors: Plan B and Periods

my girlfriend and i have always used a condom while we engage in intercourse but one time i kept going even after i ejaculated so i wasnt sure if any of it leaked out..she had her normal period on the 17th of december but we used “plan B” emergency contraceptives the next morning just to make sure she wouldnt get pregnant and then she had a “small” period again for a couple days on the 27th of december.. we have had sex since then and are still waiting for her to have her period.. is it supposed to come a month after the original period on the 17th or the one on the 27th which im assuming was caused by the plan b. we always use a condom but..we just want to be sure. thank you!!

Plan B’s effects on menstrual periods are pretty unpredictable. Sometimes, it doesn’t seem to affect them and sometimes, it can throw someone’s cycle off for months. So the general rule is: if someone takes Plan B, and they don’t get a period when expected, they want to take a pregnancy test. Plan B isn’t 100% effective, so it’s good to check. Also, what she experienced starting 12/27 probably wasn’t a “small period.”  It was likely light spotting or bleeding due to the hormones in Plan B, rather than a full-on period.

Thanks to Heather Corinna at for fact checking me on this one.

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Dr. Charlie Glickman

Charlie Glickman is the Education Program Manager at Good Vibrations. He also writes, blogs, teaches workshops and university courses, presents at conferences, and trains sexuality educators. He’s certified by the American Association of Sexuality Educators, Counselors, and Therapists, and loves geeking out about sex, relationships, sex-positivity, love and shame, communities of erotic affiliation, and sexual practices and techniques of all varieties. Follow him online, on Twitter at @charlieglickman, or on Facebook.

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