It is a little known fact that birth control medications rely heavily on the body's natural biochemistry. A large number of pharmaceutical birth control products work by affecting the chemical or hormonal balance of the body to prevent pregnancy. While most of these medications are designed to be able to work despite the multitude of variables that cannot be fully accounted for in the body, that doesn't mean that they work no matter what. In particular, the drug interaction between antibiotics and birth control pills has been noted to be rather antagonistic towards one another. A number of antibiotics have been noted to interfere with how some birth control methods work, though other types of contraceptive pills work just fine. It is currently believed that something about the way antibiotics and birth control medications work is making them incompatible with one another on a chemical level, though it is still unknown what.
It should be noted that only one antibiotic has been definitively proven to reduce the effective abilities of birth control medication. Though this declaration was made by the Mayo Clinic, one of the most respected health care institutions in the world, it should be noted that long-term studies have not been conducted into the interaction between antibiotics and birth control medications either. This implies that while only one antibiotic has been found to have an effect, it is possible that the others may have an effect and simply have not yet been explored fully by the medical community. This blank spot has been recognized and most doctors, while waiting for further studies to be concluded and the findings made public knowledge, are keen on advising couples to use backup methods, such as condoms, in conjunction with the pills.
Most doctors believe that certain medications can lower the effectiveness of birth control, though the list is mercifully short at the moment. Most medications found to have an effect are noted to cause minimal increases in risk, usually within a certain margin of error. However, some medications are believed to cause a more noticeable increase in risk, such as rifampin, amoxicillin, penicillin, tetracycline, and minocycline. Other medications that might have an effect, depending on the circumstances and some physiological variables in the body, are phenobarbitol, nitrofurantoin, sulfonamide, and cotrimoxazole. Griseofulvin is sometimes believed to have an effect, though the possibilitiy of such is not widely accepted by the medical community.
Doctors might advise their patients to lean towards caution when dealing with antibiotics and birth control medications. It is advisable to have a second birth control method on hand, such as a condom or diaphragm to minimize the risk of unwanted pregnancy. This is considered good advice whether or not the female is taking an antibiotic, since no single pharmaceutical or blocking birth control method is 100% effective. A pharmacist may also be consulted to have a better idea of how drugs interact, to provide a better idea of whether or not risks would be reduced by using more than one method of contraception.