Daily Health

Will Antibiotics Interact with Your Birth Control Pill?

Birth control pills are a popular form of contraception for good reason: they're easy to take, have been safely used for decades, and are highly effective when taken correctly. But what if your doctor prescribes you an antibiotic while you're on the pill? Will that make your hormonal contraceptive less effective?

Will that make your hormonal contraceptive less effective?

We'll dig into the common question of how antibiotics interfere with birth control so you can make the right choice for yourself the next time you have to take antibiotics and birth control pills at the same time.

How do birth control pills work?

Birth control pills typically contain two hormones, estrogen and progestin. These hormones prevent pregnancy by stopping ovulation from occurring, thickening the cervical mucus making it less likely that sperm can enter the uterus, and thinning the uterine lining so that even if an egg is successfully fertilized, it's less likely to successfully attach.

This form of birth control works by maintaining consistent hormone levels, preventing the monthly spike in estrogen that triggers the release of an egg.

Do antibiotics affect birth control?

There is a common misconception that taking any antibiotics and birth control pills at the same time will prevent the pill from working, making it important to use a barrier birth control method such as condoms during the course of antibiotics and for a period after.

While you probably don't have to worry about this interaction, there is one antibiotic, rifampin, that does make the pill less effective. Available under the brand names Rofact and Rifadin, this antibiotic is typically used to treat tuberculosis and other infections. Other types of antibiotics are much more commonly prescribed than rifampin, so it's unlikely that your course of antibiotics will interfere with your oral contraceptive.

In a Canadian Journal of Infectious Diseases review of over two decades of published research about the interaction between antibiotics and birth control pills, rifampin was found to reduce plasma concentrations of estrogen. Since one of the mechanisms required for the pill to be effective is the maintenance of steady levels of estrogen, this reduction can make it less reliable. The same review found that other types of antibiotics don't seem to have this effect.

Does amoxicillin affect birth control?

You don't have to worry about amoxicillin, and other penicillin-like antibiotics, impacting the effectiveness of the pill. This is good news, because many of the antibiotics prescribed most commonly fall into this category. Ciprofloxacin and birth control is also considered a safe combination.

If you're concerned about a specific kind of antibiotic you are prescribed making your birth control less effective, it's best to discuss it with a healthcare practitioner.

Can I take antibiotics with birth control?

Since most antibiotics don't interact with hormonal contraception, they can safely be taken together without impacting the effectiveness of either drug. If your healthcare practitioner is prescribing a course of antibiotics. make sure you let them know about any birth control you're taking so they provide personalized advice.

However, unless you're taking a version of rifampin, you'll most likely be able to keep taking your usual birth control without any concerns.

Are there any side effects of taking birth control and antibiotics?

Since most antibiotics and birth control pills don't interact, there isn't data that demonstrates side effects unique to taking them together. The exception is if you're taking rifampin, which can increase the chances of experiencing an unwanted pregnancy due to its impact on the effectiveness of birth control pills.

On their own, birth control pills have some potential side effects that may, theoretically, be more likely if the antibiotic you're taking has similar potential side effects. These include:

  • headaches or dizziness
  • a change in your usual appetite
  • diarrhea
  • nausea or vomiting

Another common side effect of birth control pills is breakthrough bleeding, also known as spotting. Some bleeding between periods is pretty common, and hormonal birth control can increase your likelihood of experiencing it. Aside from the unfortunate fact of ruining another pair of underwear, it's usually not something to be concerned about.

One of the causes of spotting can be missing a pill or taking it at irregular intervals. When you start your course of antibiotics, make sure you keep taking your contraceptive at the same time to reduce the likelihood of breakthrough bleeding.

Breakthrough bleeding is also more common in the first few months of starting the pill or switching to a different pill. If you experience spotting while taking antibiotics and you're new to the pill or you recently switched brands, there's a good chance the bleeding is just a regular side effect of the birth control.

How do I correctly take birth control pills?

Birth control pills typically come in either 21-packs or 28-packs that include seven sugar pills that make it easier to stay in the habit of taking your contraceptive on the seven "off" days. Some brands can be taken continuously for up to 91 days, so you only have to experience a period four times a year.

Regardless of which brand you take or how frequently you pause for seven days, oral contraceptives should be taken at the exact same time every day to be maximally effective. This is especially true for progestin-only pills.

Another factor that may reduce the effectiveness of birth control pills is proper absorption doesn't take place. For example if you vomit shortly after taking a dose, it's unlikely that your body had a chance to absorb the hormones in the pill.

If the antibiotic you're prescribed causes symptoms of nausea and vomiting, you may want to consider scheduling the time you take your pill when you know you won't have these symptoms, such as after any bout of nausea has passed or right before you go to sleep.

While it should be taken at the same time each day, you can start taking the pill at any point in your monthly cycle. For example, you can start taking it even if you're having a period.

What other types of drugs can impact birth control effectiveness?

While most antibiotics will typically be safe to take along with your hormonal contraception, there are some other types of drugs that can potentially interact and reduce the effectiveness of the pill. These drugs may make your hormonal birth control less effective:

  • Efavirenz, a retroviral drug used to treat HIV, may reduce the effectiveness of oral contraceptives according to a summary of available studies.
  • Griseofulvin, an antifungal medication used to treat infections such as athlete's foot, may also temporarily reduce the effectiveness of hormonal contraception.
  • A study in CNS Drugs Journal found that several antiepileptic drugs used to treat seizures can increase the likelihood of hormonal contraception failing.
  • A 2017 study found that anti-nausea drug aprepitant reduced the effectiveness of the pill.
  • A small 2004 study suggests herbal supplement St. John's Wort can interfere with hormonal contraception effectiveness.

This isn't an exhaustive list, so make sure you talk to your healthcare provider any time you start or end the use of birth control or any other drug. You should mention supplements you take as well. For example, St. John's Wort is available at drugstores and many health food stores, but even though it can be purchased without a prescription it may have an unwanted interaction with oral contraceptives.

Choosing the best birth control method for you

We've been talking about oral contraceptives broadly, but even within the category of birth control pills there are a range of contraceptive options to choose from, includinging progestin-only pills, various dose options, and a range of name brand and generic brands.

If you're worried about how other medications may interfere with the birth control pill, you may want to discuss using a barrier form of birth control with your partner, such as condoms, for the duration of the interaction. Less common barrier birth control options include spermicides and contraceptive sponges.

If you're concerned about forgetting to take an oral contraceptive at the same time every day, you may also want to consider more long-term hormonal contraceptive options such as birth control patches, birth control rings, or IUDs.

Discussing your options with a healthcare provider is the best way to determine which birth control method is right for you. You don't have to make a trip to the doctor's office to do it: you can start an assessment with Felix and explore a range of birth control options from anywhere with an internet connection. If you already have a birth control pill prescription, you can even transfer it to Felix and say goodbye to waiting around the pharmacy for your prescription to be filled.

Felix Team
Updated on:
October 4, 2021
Medically reviewed by
Dr. Sarah Lasuta
Family Physician, MD, CCFP

The views expressed here are those of the author and, as with the rest of the content on Health Guide, are not a substitute for professional medical advice, diagnosis, or treatment. If you have any medical questions or concerns, please talk to your healthcare practitioner.

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