Birth Control Pills and Diarrhea: Effectiveness & What to Do

Question
Hello,
   I take my pill everyday at 10PM. Last night at around 11:45PM I had diarrhea.  I heard that if you have diarrhea within 2 hours of taking your pill you should use back-up.  I will definitely do that but could I get pregnant?  Do I have to take another pill?  Is it considered missed?  

Thank you!

Answer
Hi Lauren,
If you just had diarrhea one time, I don't think there is a problem.  It's stated that diarrhea can decrease effectiveness, although I've never seen a study showing this.  If you're having diarrhea all day, then things are going through your intestinal tract fast, and that could decrease absorption of the pill.  If you just have diarrhea once, I don't think that means that the pill didn't have plenty of time to get absorbed.  So you'll be very safe if you use a backup, but I have my doubts that it's even necessary.