Antibiotics and birth control: can you take them together?

The pill was one of the most important medical advancements of the 20th century. It gave women all around the world the freedom to make choices about their reproductive health. That's pretty powerful! So, if you're taking oral contraceptives to prevent pregnancy, you want to make sure it works the way it's supposed to. 

You might know that some medications can have a negative interaction with birth control, making it less effective. Do antibiotics fall into that category?

Antibiotics are usually something we take for a short period of time, and it's often unpredictable when we'll need them. After all, you can't predict when you might get a urinary tract infection (UTI) or other infection that requires antibiotics. If you need to take antibiotics, will your birth control still work? 

Let's take a look. 

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In most cases, yes, you can take antibiotics while you're on birth control. There haven't been any strong studies showing that most antibiotics make birth control less effective (Simmons, 2018). 

According to the Centers for Disease Control and Prevention (CDC), there are only two types of antibiotics you shouldn't take with birth control (CDC, 2020): 

• Rifampin (brand name Rifadin)

• Rifabutin

These are part of a class of drugs called rifamycins, most commonly used to treat tuberculosis (and some infections that are resistant to other medications) (Horne, 2011). Tuberculosis is not that common in the U.S., and rates are declining every year, so these medications aren't used that often ("Trends in tuberculosis," 2019). That means most women on birth control probably don't need to worry about this particular interaction. 

If you do need to go on a rifamycin while taking the pill, you'll just need to use a back-up form of birth control (like condoms). This is because rifampin can cause breakthrough bleeding and possibly pregnancy if taken while on the pill (Zhanel, 1999). 

How does rifampin interfere with hormonal contraception? 

Even though rifampin isn't so commonly prescribed, you might be curious about how it can interfere with the effectiveness of your birth control. The way this works is that rifampin lowers the concentration of estrogen in your blood plasma. It does this by increasing liver enzymes (these are the enzymes in the liver that play a big role in processing estrogen) (Zhanel, 1999). Since combined oral contraceptives work by preventing ovulation through a combination of the hormones estrogen and progestin, decreasing estrogen hormone levels gets in the way of an important part of the pill's function (Cooper, 2020).

What about other types of antibiotics? If you get a UTI, your healthcare provider will probably prescribe one of the many other antibiotics, such as trimethoprim-sulfamethoxazole (brand name Bactrim) or nitrofurantoin (brand name Macrobid). Can you take those with hormonal birth control? 

You can! The only antibiotics that might interfere with birth control are rifampin and rifabutin. All other antibiotics, including common antibiotics like amoxicillin and ciprofloxacin, should be safe, even if you're taking contraceptive pills (Simmons, 2018). 

Your healthcare provider might still recommend using a back-up form of birth control while you're on the antibiotics, just to be extra safe. Be sure to follow the medical advice of your healthcare provider. 

Antibiotics aren't the only medication interaction you need to be concerned about when taking birth control. Most medications are completely safe with combined oral contraceptives, but there are certain other drugs that can interfere with the pill, making it work less effectively. There are two main types of drugs that can be problematic with the pill: 

• Antiretrovirals (drugs used to treat HIV) 

• Anticonvulsants (drugs used to treat and prevent seizures)

There's only one antiretroviral that can interfere with the pill, a drug called fosamprenavir (brand name Lexiva) (Britton, 2020). If you're on the pill and have HIV, your healthcare provider will likely recommend using a back-up method of birth control. Or, she may prescribe a different HIV medication.

With anticonvulsants, the list of drugs that interact with hormonal contraceptives is much longer. If you have a seizure disorder, you'll need to work closely with your healthcare provider to find the right combination of drugs for you. The anticonvulsant (also called antiepileptic) drugs that can make birth control less effective are (Reddy, 2010): 

• Carbamazepine (brand name Tegretol)

• Felbamate (brand name Felbatol)

• Lamotrigine (brand name Lamictal)

• Oxcarbazepine (brand name Trileptal) 

• Phenobarbitone (brand name Luminal)

• Phenytoin (brand name Dilantin)

• Primidone (brand name Mysoline)

• Topiramate (brand name Topamax)

There are many other anticonvulsant drugs that are perfectly fine to take while on the pill. If you need to be on one of the above medications, though, you should use another form of birth control. 

Lastly, some herbal medicines, such as St. John's wort, can interfere with the pill, causing side effects such as breakthrough bleeding. It's possible these substances can decrease the effectiveness of birth control pills, so back-up birth control is recommended (Murphy, 2005). 

While most medications can be taken safely with birth control, there are some medications that must be taken with some form of reliable birth control since it's unsafe to get pregnant while taking them. Drugs that fall into that category are teratogenic, which means they can cause malformations in an embryo. Here are some of the most common teratogenic drugs that should be taken with a reliable form of birth control (Tsamantioti, 2020): 

• Isotretinoin—This oral acne medication is better known by its brand name, Accutane. It is so dangerous to get pregnant while on isotretinoin that patients are required to sign an agreement to be on two reliable forms of birth control while taking it. 

• Antiepileptic drugs—Wait a minute, didn't we just say in the previous section that many antiepileptic drugs make hormonal contraception less effective? Yes, but many antiepileptic drugs are teratogenic, too. It's important to follow your healthcare provider's advice about using another reliable birth control method while taking antiepileptic or anticonvulsant drugs. 

• Certain antibiotics—As we've discussed, most antibiotics are safe to take with birth control, with the exception of rifampin and rifabutin. There are two types of antibiotics, though, that should be taken with birth control since they are unsafe during pregnancy. Those are tetracycline and fluoroquinolones. 

• Warfarin—This is an anticoagulant medication used for several purposes, including in patients with clotting disorders, to treat an active blood clot, and in patients with mechanical heart valves. This drug is unsafe during pregnancy, so if you need to be on it long-term, you'll need to use a reliable form of contraception at the same time. 

• Antithyroid medications—Certain antithyroid medications, namely propylthiouracil, methimazole, and carbimazole, should be taken with birth control.

• Fluconazole—In high doses, this antifungal medication (known by its brand name, Diflucan) can cause birth defects. In low doses, it's probably safe, but if you need to be on a higher dose, birth control is recommended (Kaplan, 2015). 

If you're taking combined oral contraceptives to prevent pregnancy, the last thing you need is to worry that they may not be working properly and cause an unintended pregnancy. While most medications are safe to take while on the pill, it's important to discuss any concerns with your healthcare provider if you need to go on any other medications, whether long-term or temporarily. If you're taking a medication that might decrease the effectiveness of your birth control pills, just use a back-up form of birth control during that time.

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Current version

January 05, 2021

Written by

Rachel Honeyman

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.