You’ve missed your period and you’re surprised why. Afterall, you’re on an oral contraceptive and you can’t be pregnant. There might be a simple reason for this, antibiotics! Now, we must say that most antibiotics do not have an effect on contraceptives, however, there are a few that interact with hormonal contraception and make it less effective.
The use of antibiotics can potentially reduce the effectiveness of birth control pills if taken at the same time. Some antibiotics under the rifampin family — which are used to treat or prevent diseases such as tuberculosis — cause an increased break-down of estrogen by enzymes in the liver. This decreases the overall levels of estrogen in the body and the effectiveness of hormonal contraception.
In theory, antibiotics kill the bacteria responsible for converting inactive chemicals to the active estrogen and this may lead to it interfering with the effectiveness of birth control pills. Although it has not been definitively proven that unwanted pregnancies can happen this way, pharmaceuticals caution that antibiotics could decrease the effectiveness of oral contraception.
When taking antibiotics whilst using hormonal contraceptives such as – the pill; an implant; a patch; a vaginal ring – individuals are advised to:
- Use additional contraception, in tandem with the pill, such as condoms.
- Change to a different method of contraception altogether.
If you’ve been taking rifampin for less than 2 months and want to continue using it, consider discussing this with your doctor. You may be asked to take this contraception in a different way from usual and use condoms as well. You’ll need to continue this for 28 days after finishing the antibiotics.
Contraceptives that are not affected by rifampin include:
- the progestogen-only injection
- an intrauterine device (IUD)
- an intrauterine system (IUS)
An option for individuals using a contraceptive implant, but need to take a short dose of rifampin to ward off meningitis, is a single dose of the progestogen injection. The implant stays in place while you’re covered by the injection. Ask your doctor about the different types of contraceptives available to you.
If you become pregnant while taking hormonal contraception, it will not usually affect your health or that of your baby. But you should tell your GP if you think you may be pregnant.
It’s important to have your doctor run a drug interaction screen each time you start or stop taking a medication. Also, remember that birth control pills are likely to fail at least 1% of the time in peak conditions.
Be open and honest with your doctor about which medication you’re on — regardless of whether it was prescribed or not — so they can give you the best care.
How Marie Stopes can help you
Marie Stopes South Africa offers a wide range of different contraceptives for men & women. Whether you’re interested in a monthly option like the pill (oral contraception) or patch; or a long-acting method like an implant or IUD, we can help you find a contraceptive method that suits your lifestyle.