Birth Control and Antibiotics —
What You Need To Know

By Lizzie De La Cruz
September 7, 2020

Say you're at urgent care because you're sick and find out you have strep throat, so your medical provider gives you a round of antibiotics to clear it. While you're happy to be getting treatment for your symptoms, you remember that reading how antibiotics might reduce the efficacy for your birth control—and ask yourself, "what does that mean, exactly?" The good news is, that common antibiotics, like amoxicillin, which are used to clear infections won't make your birth control any less effective! However, with the laundry list of antibiotics used to treat all the different infections out there—it's common to wonder what antibiotics interfere with birth control?

What Are Antibiotics?

Antibiotics are a type of medicine used to stop the spread of bacterial infection in the body. Antibiotic means "against life" since this medicine works to kill germs in the body, and more specifically, to kill bacteria. For the history buffs out there, here are a few quick facts: Antibiotics were created in the 1920s to combat the immense number of people dying from minor bacterial infections, such as strep throat. In the 1940s, antibiotics became readily available throughout the United States, and as a result, life expectancy rates increased and more humans were able to survive what were once deadly infections. Yay!

Now that we've got that out of the way, here's the important part: Antibiotics are only able to kill bacterial infections. Other viruses, such as the stomach flu and some bronchitis infections, are not able to be treated with antibiotics. There are several different types of antibiotics, but most are categorized as either broad-spectrum or narrow-spectrum. Broad-spectrum antibiotics work on several types of bacteria, while narrow-spectrum antibiotics work on only specific types of bacteria. For this reason, antibiotics should only be taken when prescribed by a licensed medical provider.

What Are Antibiotics Used For?

There are several types of bacterial infections that antibiotics can treat. If you are taking prescription medication and unsure whether they are antibiotics, it is essential to find out for sure. Common infections treated with antibiotics include:

Your medical provider can tell you if antibiotics are right for your infection or if they aren't an effective option. Some infections are not obviously either bacterial or viral, so your provider may run a few tests before prescribing medication.

Potential Side Effects Antibiotics Can Have On Birth Control

The idea that antibiotics can reduce the effectiveness of birth control is a long-held belief by many women (and the cause of many long nights spent worrying). However, this belief is not necessarily rooted in fact. According to the Cleveland Clinic, the only antibiotics proven to potentially interfere with the efficacy of birth control are rifampin and rifabutin. These high-powered antibiotics are used primarily to treat tuberculosis, not common vaginal infections or chronic sinus issues!

These two types of antibiotics are inducers of the hepatic enzymes. These enzymes are necessary in order for birth control to be effectively metabolized in the body. When taking rifampin or rifabutin, a woman's birth control may not be fully absorbed and therefore may not effectively prevent pregnancy. Additionally, rifampin can cause irregular periods which also increases the risk of getting pregnant while taking birth control.

Additionally, according to MedicineNet, rifampin and related antibiotics can potentially lower the effectiveness of birth control by causing certain liver enzymes to increase the breakdown of estrogens. Estrogen is a primary hormone used in birth control pills to suppress ovulation and prevent pregnancy. When estrogen breaks down more quickly, this decreases the total amount of estrogen in the body and can result in an unwanted pregnancy.

Another way this type of antibiotic may reduce the efficacy of birth control is by lowering the re-circulation of estrogen in the body. This is because antibiotics reduce the bacteria in the intestine responsible for converting chemicals into active estrogen and then re-circulating it back into the body. Unwanted pregnancy is theoretically possible in this case; however, no studies have proven that conception can happen due to this scenario.

How To Avoid Pregnancy If Taking Antibiotics

When taking antibiotics, your pharmacist may recommend using a backup form of contraception, like a condom, for the time period in which you use antibiotics. This ensures that unwanted pregnancy doesn't happen.

Antibiotics and Birth Control: Myths and Facts

There are several myths circulating around the combined use of antibiotics and birth control. We're here to debunk these myths, and hopefully help ease your mind a bit the next time you have to take antibiotics. Let's take a look at some of the most common myths:

Myth #1: Any type of antibiotic can interfere with the effectiveness of birth control

As previously discussed, there are only two types of antibiotics that have been shown to potentially reduce the efficacy of birth control: rifabutin and rifampin. These antibiotics fall under the category of rifamycins and are primarily used to treat tuberculosis and meningitis. Most other antibiotics, like amoxicillin, will not interfere with how effective oral birth control is at preventing pregnancy.

Myth #2: Any type of antibiotic will treat a bacterial infection

This is also not true. There are several types of antibiotics, and each type treats a specific form of bacterial infection. For example, an antibiotic that treats a urinary tract infection (UTI) will likely not be able to effectively treat strep throat. Because of the various types of antibiotics available, it's important to work with your medical provider and undergo any necessary tests to accurately diagnose your bacterial infection and determine the most appropriate antibiotics for your specific condition.

Myth #3: Oral birth control pills are the only types of contraception that can be affected by birth control

While there isn't a ton of research out there on this subject, other types of birth control, such as transdermal contraception solutions, still rely on certain hormones to prevent unwanted pregnancies. Because rifamycins can impact how the body absorbs and uses hormones, it's still important to use a backup form of contraception when taking these antibiotics to avoid getting pregnant.

Even when you take birth control pills at the same time every day, they still come with an estimated 1% chance of failing. Forgetting to take a pill or not taking it at the same time each day can further decrease the effectiveness of birth control. Taking your birth control consistently and using a backup form of contraception when on antibiotics is the best way to prevent an unwanted pregnancy.

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