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You’ve probably heard before that you shouldn’t use antibiotics in combination with your birth control. Perhaps you’ve even read it on your birth control packaging as a warning, but is it actually a cause for concern? Do antibiotics affect birth control? Before we get to that, let’s quickly discuss what birth control is and how it works with the women body.

Hormonal contraceptives all contain a small amount of hormones including estrogen, progestin, or a combination of the two. Combination birth control pills like Alesse, Yaz, Aubra, and Yasmin are an example of this as these brands contain both estrogen and progestin. Birth control is typically taken to prevent pregnancy but there are some cases where women use it for treatment of acne, regulating heavy periods, or excessive cramping.

It’s the hormones in a woman’s body that control the release of an egg from the ovary (ovulation), which occurs once a month. If a woman is not taking birth control and has unprotected sex, an egg will then become fertilized by the sperm and pregnancy will occur. But, when a woman takes birth control, the hormones in birth control actually trick the body so that ovulation doesn’t occur. Without ovulation, pregnancy isn’t possible!  

Antibiotics and Hormones

So, what effect do antibiotics have on this process, and do antibiotics affect birth control and its effectiveness? Many drug interactions can change the chemical composition in your body and may cause medications like birth control to become less effective. If you have ever received a prescription from your doctor, you will know that they’re required to ask you for a list of medications your taking before you start taking another. This is standard procedure to ensure that the medication you’re taking does not counteract another.

The latest research points to a negative correlation between birth control pills and antibiotics, meaning most antibiotics don’t reduce the effectiveness of birth control. However, there is an important exception to this. There are in fact two oral antibiotics that have been reported to decrease the effectiveness of birth control; rifampin, a drug used to treat tuberculosis, and griseofulvin, to treat fungal infections.

These antibiotics have an effect on birth control because they both increase the activity of an enzyme in the liver, which breaks down hormones faster than normal. This causes the birth control to fail because the hormone levels are reduced and become less effective. Its worth noting that both antibiotics are very rarely prescribed. So, while it is possible for antibiotics to have a negative effect on birth control, it is unlikely that it will happen.

As topical antibiotics are not absorbed into the bloodstream, there is no chance of impacting the effectiveness on birth control. So, if your doctor has prescribed you an antibiotic cream, you don’t’ have to worry about it interfering with your birth control.

Common Reasons Birth Control Fails

Even when used with perfect use, birth control is not 100% effective and can result in pregnancy. There are several reasons that birth control can fail and become ineffective. The most common reasons that birth control fails are:

  • Interference with other drugs / medications
  • Human error – not following the instructions
  • Storage temperatures – causes medication to become inactive
  • Obesity
  • Smoking

Using a Backup Method

Although there have been some cases reported of contraceptive failing when a woman takes antibiotics, it doesn’t happen regularly. To ease your mind while taking antibiotics, your doctor will generally recommend that a backup method of birth control is used during this time. Typically, a condom, spermicide, or a female condom are all good options to use as a backup method.

If you are taking both antibiotics and birth control at the same time and wondering do antibiotics affect birth control, you should speak with your doctor and find out how long you should use a backup method for.

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