If you are using birth control pills, you’ve probably been advised that they will be less effective if you are simultaneously taking an antibiotic. Some people suggest also using condoms to protect against pregnancy if you need to be on an antibiotic.
Despite the widespread fears about this (and the warning labels you may see on some prescriptions), there is no good science to suggest that birth control pills don’t work as well while taking antibiotics. One review in Archives of Family Medicine concluded that the scientific literature does not suggest that common antibiotics reduce how well birth control pills work. Some birth control pills have a low hormone dose to prevent pregnancy, and some of these might work less well when combined with antibiotics; but again, the difference in efficacy is minimal. Another study looked at 356 patients in three 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 taking just the birth control pill. Remember, birth control pills fail at least 1 percent 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 that there is a possibility of one antibiotic, rifampin (a drug usually used for tuberculosis), making birth control pills less effective. In a study of thirty women, the level of the hormone in the birth control pill that prevents you from ovulating was lower in the women’s blood when rifampin was also being taken. However, none of the women in the study became pregnant as a result of taking rifampin and birth control pills at the same time.
Future research of new drugs and rare antibiotics may uncover that you should not take antibiotics and birth control pills at the same time, but the current science suggests that this is rarely a concern. It is much more important to take your birth control pill every day at the same time than to spend time worrying about your antibiotics.
MYTH, HALF-TRUTH, OR OUTRIGHT LIE?
You can’t get pregnant when you’re on the pill
In the course of a year, five to eight out of one hundred women using the pill will have an accidental pregnancy. Even if you use it perfectly, there is still a one out of one hundred chance you can become pregnant. Those odds are better than other methods (twenty-seven out of one hundred women will get pregnant using the withdrawal method), but the odds aren’t zero. Birth control pills work best when taken every day at the exact same time of day. If you take the pills absolutely perfectly, it’s highly unlikely that you’ll get pregnant. However, if you are forgetful about taking your pill at the same time every day, your chance of getting pregnant while using the pill may be slightly higher. And worse yet, missing even one day of the pill can significantly increase your chance of getting pregnant, so this one is a half-truth.