These types of antibiotics can increase the enzymes in your body. This is known as being "enzyme-inducing" and can affect hormonal contraception. If you're taking enzyme-inducing antibiotics while using hormonal contraception, to avoid getting pregnant you'll need to:.
But the patient information leaflet that comes with other types of antibiotics may say they could affect your contraception. Find out about other medicines that may affect contraception. If you're going to take rifampicin or rifabutin for more than 2 months, you may want to consider starting, or changing to, a contraception method that's not affected by these medicines. If you're taking rifampicin or rifabutin for less than 2 months and want to continue using the same hormonal contraception, you must discuss this with your doctor.
You may be asked to take this contraception in a different way from usual and use condoms as well. One option for women who have a contraceptive implant and need to take a short dose of rifampicin for preventing meningitis, for example is a single dose of the progestogen injection.
You and your doctor can get up-to-date guidance about contraception and antibiotics from the Faculty of Sexual and Reproductive Healthcare. You do not normally need to use additional contraception if you're taking antibiotics other than rifampicin and rifabutin.
But if the antibiotics or the illness they're treating cause diarrhoea or vomiting, absorption of the contraceptive pill may be affected. For more information, see What if I'm on the pill and I'm sick or have diarrhoea? Page last reviewed: 28 January Next review due: 28 January Will antibiotics stop my contraception working?
Where to get contraception. Because there's no full agreement on how antibiotics interact with hormonal birth control, you should always ask your doctor what they recommend for your specific situation. They may want to adjust your birth control dosage or recommend using an extra birth control method while you're taking antibiotics.
Antibiotics don't typically have any effect on your menstrual cycle. If you notice irregular periods around the time you're taking antibiotics, it's likely to be caused by illness or stress.
They may not affect your period, but some antibiotics can make you more at risk for a yeast infection. For more information, take a look at the pill package insert. It might say that women have had "contraceptive failure and breakthrough bleeding" after taking antibiotics like ampicillin. Drugs like Rifampin interfere with birth control pills at the hormonal level. To understand why you need to know how birth control pills affect your hormones.
Hormonal birth controls contain some combination of the hormones estrogen and progestin. Depending on which kind of birth control you use, these hormones work in your body to do at least one of the following:. Prevent ovulation. Each cycle, the ovary releases a mature egg. This release is called ovulation. The days around your ovulation are the only time during each menstrual cycle that you can get pregnant. If you don't ovulate at all, you can't get pregnant.
Keep sperm from making it to the uterus. Birth control can do this by causing your cervical mucusyou've probably heard this referred to as "vaginal discharge" to get thicker. Thicker cervical mucus makes it incredibly hard for sperm to swim to an egg. Make implantation unlikely. Hormonal birth control can make changes to your uterus lining that decrease the chances of a fertilized egg being implanted.
Even if a sperm somehow makes it to an egg to fertilize it, you only get pregnant if it successfully implants in your uterine lining. No implantation, no pregnancy.
Rifampin can keep your birth control from doing its job by causing your liver to break down estrogen faster than it usually would. When estrogen gets broken down too quickly, it can't drive the changes in your body that normally keep you from getting pregnant. Note: Copper IUDs don't use hormones to prevent pregnancy, so they won't be affected by any medicine that may change your hormone levels. Rifampin may be the only antibiotic proven to lower the effectiveness of hormonal birth control, but it's not the only drug that can do so.
These medicines can also increase your chances of getting pregnant while taking hormonal birth control:. Some protease inhibitors used to treat HIV. Certain anti-seizure medications. Griseofulvin, an antifungal medication. The length of time that antibiotics or other drugs can affect birth control depends on which medicine you're taking.
Some medications will only affect hormone levels while you're taking them. Others can have effects that linger for up to a week or even a month after you stop taking the medicine. If you're prescribed something that makes your birth control less effective, your doctor will be able to tell you how long you should use a backup method of birth control. This is a drug that is prescribed to treat tuberculosis and other bacterial infections.
Unfortunately, rifampin has been shown to decrease hormone levels in birth control pills as well as the birth control patch and vaginal ring. This means it can change the way your contraception works and allow a chance of pregnancy.
What about other antibiotics? A study published in the Journal of the American Academy of Dermatology concluded that hormone levels remain unchanged when the following commonly prescribed antibiotics are taken with birth control pills:.
Did you get pregnant or know someone who got pregnant while on antibiotics and birth control pills at the same time? There may be other factors that contributed. In addition, if you are vomiting, you may not properly absorb your birth control pill. A condom or other form of backup birth control is often used when having intercourse during antibiotic treatment.
Keep in mind that your birth control pills can also make other drugs less effective such as analgesics and blood pressure medications , and the effects of antidepressants, bronchodilators, and tranquilizers can actually be increased when taken with birth control pills.
When in doubt about your medications, always consult your gynecologist.
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