Does Diarrhea Decrease Birth Control Pill Effectiveness?

Jamey asked

Hi, I was taking antibiotics for a UTI when I had diarrhea one day only once. And it was on pill 6 of the pack of birth control pills (alysena 28). I was using a condom as a back up while on the antibiotics and for 7 days after just to be safe as a precaution. Would the diarrhea of messed up my pill for my next placebo week or anything? I never missed a pill and take it every morning between 730-800AM.

Answer

Hi Jamey and thank you for reaching out to us. Potentially ineffective birth control is a bit scary so I’m glad that you took the extra precaution.

Severe diarrhea can cause birth control to lose its effectiveness. It’s thought that this occurs because it has much less time to be absorbed in the small intestine.

Some birth controls include directions on how to handle this, others don’t, but this is a general recommendation:

“If you have vomiting or diarrhea within 3–4 hours of taking your tablet, take another pill. Continue taking all your remaining pills in order. Start the first pill of your next pill dispenser the day after finishing your current pill dispenser. This will be 1 day earlier than originally scheduled. Continue on your new schedule.”

“If you have vomiting or diarrhea for more than 1 day, your birth control pills may not work as well. Use an additional birth control method, like condoms and a spermicide, until you check with your healthcare provider. “

So if this occurs in the future, you can take an additional dose and as long as your diarrhea resolves, you should be perfectly fine.

That being said, when in doubt, extra precaution is always good so I’m glad that you used a backup method. Since you used a backup method and it’s been over 7 days, you should not be at an increased risk of pregnancy.

Feel free to write to us again in the future!