Can Your Birth Control Pill Fail if You Take Antibiotics?

Do birth control pills work just as well when you are on antibiotics? Guest authors Dr. Aaron E. Carroll and Dr. Rachel C. Vreeman debunk this popular myth in an excerpt from their new book Don't Put That in There!: And 69 Other Sex Myths Debunked.

QDT Editor
3-minute read

Myth: Birth control pills don’t work as well if you’re on antibiotics

Birth control pills are a pretty good method of birth control. They’re not perfect; short of abstinence, nothing is. But there is a widespread belief that birth control pills will not work as well if you take an antibiotic at the same time.  Some people suggest using condoms or some other additional method of contraception to protect against pregnancy if you need to be on an antibiotic. 

Despite the frequent fears about this, and the warning labels you may see on some prescriptions, no good science exists to suggest that birth control pills don’t work as well while taking antibiotics.  One review by the American Academy of Family Physicians concludes that, while there are not a lot of good studies to help us answer the question, the scientific literature does not suggest that common antibiotics reduce how well birth control pills work.

Some birth control pills have a low dose of the hormone to prevent pregnancy, and some of these might work less well when combined with antibiotics; but again, these decreases are very small.  Another study looked at 356 patients in 3 dermatology practices with a history of long-term use of antibiotics and birth control pills together.  There was no statistically significant difference between how many women got pregnant in the group on both antibiotics and birth control pills, and the control groups where women were on just the birth control pill. 

Remember, birth control pills fail at least 1% of the time even in ideal conditions.  And in studies that look at what happens in real life when women take an antibiotic with their birth control pill, the rate of getting pregnant doesn’t seem to change.

Some science does suggest a theoretical possibility that one antibiotic, rifampin, might have the ability to make birth control pills less effective.  In a study of 30 women that looked at the levels of drug in their blood, the level of the hormone in the birth control pill that prevents you from ovulating was lower when rifampin was used.  None of these women got pregnant in the study, but the possibility was there. Rifampin is not an antibiotic that most women are going to encounter. It is usually used for tuberculosis or sometimes for meningitis.

Of course, future research with new drugs or more rare antibiotics might still mess up your birth control pills, but the science right now suggests that this is rarely a problem.  It is much more important to take the pills every day and at the same time every day than to worry about most antibiotics.  Look, there is no harm to wearing a condom if you want to be extra careful.  But, you should not stop taking your antibiotic just because you are worried it will affect your birth control pill's effectiveness. 

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Dr. Aaron E. Carroll is professor of pediatrics at Indiana University’s School of Medicine and director of the Center for Health Policy & Professionalism Research and the Center for Pediatric and Adolescent Comparative Effectiveness Research. Dr. Rachel C. Vreeman is an associate professor of pediatrics at Indiana University School of Medicine and codirector of Pediatric Research for the Academic Model Providing Access to Healthcare (AMPATH) in Kenya.



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