Earlier studies seemed to indicate that if antibiotics andbirth control pills are taken simultaneously, more women gotpregnant than one would normally expect. Medications likeampicillin and tetracycline are suspected of interferingwith the effectiveness of birth control pills. However, fromall the studies that saw this connection, they have shownthat antibiotics do not increase the pregnancy rate at all,and points out that older information was not reliableenough to draw conclusions about pregnancy rates on any ofthe antibiotics. From recent studies, some reportedantibiotics show no signs in affecting the metabolism ofbirth control pills. An example of such antibiotics include. Cipro, which does not alter metabolism; and Diflucan, aproduct that does not decrease estrogen but actuallyincreases it.
Still, if one takes both antibiotics and birth controlproducts, the contraceptive may not work, thereforeincreasing the chances of becoming pregnant. Oralcontraceptives or birth control pills work by affecting theproduction of certain hormones that can stop a woman’sovaries from releasing eggs; or make the lining of theuterus thinner so that fertilized eggs cannot attach to theuterus; and it can make it harder for the sperm to reach theeggs. All these are done by two hormones: the estrogens andprogestins.
The reason behind antibiotics and birth control when takentogether is that some antibiotics make it hard for the bodyto absorb the hormones contained in birth control pills.
Other antibiotics makes the body get rid of the hormoneseven faster, and if either of this happens, the lowerhormonal levels in the body may allow a woman to getpregnant even if she does not want to. Such antibioticscause the enzymes in the liver to increase the break down ofestrogens and thereby decrease the levels of estrogens inthe body and the effectiveness of the birth control pills.
Some of the antibiotics with this kind of effect includerifampin, penicillin, tetracyclines, and trimethoprim, amongothers. Another reason on how antibiotics interfere with theeffectiveness of birth control pills is by the reduction ofre-circulation of estrogens within the body. Estrogens inbirth control pills are broken down by conversion in theliver to other chemicals which are secreted into theintestines in the bile produced by the liver. Bacteria inthe intestine are able to convert these chemicals back intothe active estrogen which is then re-absorbed into thebody.. This re-circulation is called entero-hepatic cycling.
Theoretically, antibiotics can kill the bacteria thatconvert the inactive chemicals to the active estrogen, and,therefore, may interfere with the effectiveness of birthcontrol pills. Unwanted pregnancies could occur. Although ithas not been proven that unwanted pregnancies can occur bythis means, drug manufacturers caution that antibioticscould decrease the effectiveness of birth control pills.
However, other antibiotics will not affect contraceptiveimplants. An implant is a capsule inserted under the skin onthe inside of a woman’s upper arm. This reduces the chancesof becoming pregnant by releasing progestin into one’sbloodstream. To make sure that pregnancy prevention is athand, always inform the doctor if one is taking birthcontrol pills. The doctor may then prescribe anothermedication, or discuss possible drug interactions. If incase one is under prescription medications, one can stilltake birth control pills only if there is a barrier form ofbirth control. This includes the use of a condom, adiaphragm, or a cervical cap.