Diarrhea and Birth Control Pills

Does Having Diarrhea Mean You Can't Count on Your Birth Control Pills?

Woman with birth control pills
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One of the major reasons for an unintended pregnancy is the inconsistent use of birth control pills. Typically that happens as the result of forgetting to take the pills as prescribed. However, it is possible that when a person has diarrhea, the effective dosage of the contraceptive medication can be compromised. Let's take a look at what this means for you, whether you are experiencing an acute episode of diarrhea, or are dealing with it on a more chronic basis, because you have diarrhea-predominant IBS (IBS-D).


Acute Cases of Diarrhea and the Pill

If your diarrhea has come upon you suddenly due to an illness or food poisoning, it is likely that the effectiveness of your birth control pills may be affected. This is because the active ingredients in your pill formulation may not be adequately absorbed. The rule of thumb is to assume that you can no longer count on your pills to keep you from getting pregnant if you have severe diarrhea for more than 24 hours. This means that you have passed six to eight watery stools in a 24 hour period for more than one day.

How to proceed? Call your physician and tell them what is happening. Most likely they will tell you to try to continue to finish out your pack of pills but to be sure to use an alternate method of contraception for the next seven days.

What If You Have Chronic Diarrhea from IBS?

The question as to whether IBS diarrhea affects the effectiveness of birth control pills is an excellent one.

As discussed above, since diarrhea may interfere with absorption of hormonal ingredients, thus limiting effectiveness, it is quite understandable to wonder if this applies to diarrhea bouts that are part of IBS, particularly since the ramifications are so serious -- an unwanted pregnancy.

Unfortunately, research on the subject appears to be almost non-existent.

I was able to find one meta-analysis regarding hormonal contraceptive use in women with inflammatory bowel disease -- a different medical problem than IBS, but with chronic diarrhea as a shared symptom. This review concluded that there was no difference in absorption rates of "higher-dose combined oral contraceptives between women with mild ulcerative colitis and small ileal resections" and placebo subjects.

The hormones of the pill are absorbed primarily at the level of the small intestine and therefore It is thus possible that although they can feel pretty severe, diarrhea episodes from IBS may not result in the absorption difficulties that occur when your body is dealing with an infection. If this is the case, then one should be able to have confidence that your birth control pills are working in spite of your IBS. However, since the stakes are high, you should have a frank discussion with your obstetrician/gynecologist about your digestive symptoms so that together you can make a decision as to the most effective birth control option for you.


"Combination birth control pills" Mayo Clinic Accessed January 12, 2016.

Zapata, L., et.al. "Contraceptive use among women with inflammatory bowel disease: A systematic review" Contraception 2010 82:72-85.

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