What’s the Deal with Antibiotics and Birth Control?

[ ♪INTRO ] You might have heard that you should use a
back-up method of protection if you’re taking birth control pills and antibiotics at the
same time. You might have even read it on the pill package
itself! And if it’s on the packaging, well, you’d
assume there’s good reason. But… It turns out the majority of reports of this
are inconclusive and anecdotal. In fact, it seems like only one type of antibiotic
is actually worth the extra caution. But when you look closely at how birth control
pills work, it makes sense that doctors would be worried. Oral contraceptives use hormones to prevent
pregnancy. They include estrogens and progestins, or
just progestins alone — though most include some kind of estrogen, because they’re better
at stopping the pituitary gland from releasing the hormones needed for egg development and
preparing the uterus for implantation. Basically, estrogens prevent ovulation really
well. Though, they only work if there are enough
of them in the blood. That’s why the pills have to be taken every
day. But, blood estrogen levels aren’t entirely
dependent on pills, because your body makes some estrogens, and it can recycle them. Like lots of things, estrogens undergo a process
called conjugation in the liver where they’re combined with other molecules — often glucuronic
acid. This creates larger compounds that are secreted
into the intestines in bile. From there, they get excreted in feces — unless
gut bacteria step in. Some bacteria chop off the added bit, thereby
converting these chemicals back into active estrogens, which can get reabsorbed. And research in animal models has suggested
this recycling could be important for ensuring blood estrogen levels are high enough for
effective contraception. That’s where the concern with antibiotics
comes from. You see, in theory, antibiotics could kill
off some or all of the intestinal bacteria involved in this estrogen recycling program
— which could, in theory, make the pills less effective. The thing is, there just isn’t really any
evidence this happens. A 2002 review noted that neither estrogen
nor progestin levels seem to drop when people take antibiotics. And a 2011 study of 1,330 cases of pregnancies
that occurred while people were on birth control found no connection between contraceptive
failure and antibiotic use. Indeed, despite decades of research, a 2018
systematic review failed to find evidence that any of the major classes of antibiotics
interfere with birth control. There is one exception to all of this, though:
Rifampin, an antibiotic primarily used to prevent and treat tuberculosis. It can cause a notable drop in estrogen levels,
and it has been linked to unexpected pregnancies. But here’s the weird part: the way it interferes
with birth control has nothing to do with gut bacteria. You see, your liver manages the levels of
all sorts of hormones and drugs. So it produces a variety of enzymes that break
things down or otherwise prepare them for excretion. And it just so happens that this particular
bacteria-killing compound signals liver cells to ramp up the production of some of these
enzymes. Specifically, rifampin increases the activity
of cytochrome P450s or CYPs, for short. One of the things they’re involved in is
the conjugation of estrogens — they prepare the estrogen molecule for the attachment of
glucuronic acid and other conjugates. So by increasing CYPs, rifampin speeds up
the conjugation of estrogens — and so much so that it leads to increased excretion of
them. Which means its effects may not be limited
to oral contraceptives. Other estrogen-containing birth control methods
like the patch and the ring could be impacted too, but there hasn’t been enough research
to say for sure. And this isn’t just about estrogens. CYPs also seem to be involved in the excretion
of progestins. And rifampin also increases production of
globulin, a protein in your blood that binds circulating progestins and reduces their availability. So it probably interferes with progestin-only
pills, too, though again, more research is needed. In fact, CYPs help your liver deal with a
lot of things, so birth control is just one of many drugs that rifampin interferes with. Still, it’s not used for a lot of infections
— mostly tuberculosis — so the odds are, if you’re taking an antibiotic for anything
else, it’s not going to interfere with your preferred method of contraception. But some still think it’s better to be safe
than sorry, which is why the warnings on basically all antibiotics persist. Thanks for watching this episode of SciShow! If you’re hungry for more information about
antibiotics, might I suggest our video looking at some weird places we might find more of
them. And to have more awesome science videos delivered
right to your YouTube feed, be sure to click that subscribe button and ring the notification
bell! [ ♪OUTRO ]

100 thoughts on “What’s the Deal with Antibiotics and Birth Control?”

  1. Tell this to my niece who is a Nurse and got pregnant when taking Antibiotics and on Birth Control. PS she doesn't have TB.

  2. So… anybody else realize how the women on Rifampin were basically getting knocked up on a really miserable and highly contagious disease? Seriously, how horny can a guy get where that's worthwhile (and I say "guy" here because I don't know of anyone with TB who has a high libido)

  3. Or just eat alot of SOYBEAN products. Soybean mimic the production of estrogen … They used soybean to help woman skip menopause

  4. I have two kids. BOTH are birth control babies. I was diligent with my BC, but 15 years ago, this warning was only in tiny print at the bottom of the three page patient info packet that came with the antibiotics. SUPER easy to miss, and my GP didn't say a word when he prescribed me antibiotics. (gender bias with a teenage girl, maybe? I was just 19 when I got pregnant the first time). My OB/GYN thinks my body hypermetabolizes BC and that's why it just never worked for me. Thank Science for IUD's!

  5. 🗣 It harms the digestive system & cause fungus & candida to grow….want the evidence all these autoimmune disease

  6. Really. Stop playing pronoun games. Don't buy into the Gender-fluid or inclusive language nonsense.

    You are a science channel and should know better.

    We don't care about "people" getting pregnant. We care about women getting pregnant. If you are including all people instead of women, 50% of your sample is irrelevant as the men could never get pregnant no matter how much of "the pill" they take in any combination with antibiotics.

  7. Ahhh, yes my old nemesis, cyp450…

    Let's not fight again…

    You're not my enemy, so why do you feel the need to keep trying to kill me???


  8. so the ones who said they were taking antibiotics and birth control but still got pregnant could have just not have been taking the birth control pills? guys "wear condoms" and get women pregnant so…

  9. This is how my daughter came to be. Wife was on pill, she had to take 3 days of antibiotic – pow! She was pregnant. Best thing that ever happened to me 🙂

  10. I took my oral birth control religiously and had a alarm which I would stop whatever I was doing to take had one night of drinking and ended up pregnant, so I'm a firm believer things can have a negative effect on birth control. Had a IUD and had a ectopic pregnancy. Maybe I'm just fertile as hell or super unlucky either way I had the best blessing of my life, but birth control most definitely isn't a solution if you ask me😂😂😂

  11. Wait… that's how big a Nuvaring is? So you're basically stuffing a spermicidal bangle up your hoo-hah? Modern medicine is weird.

  12. Should probably wrap it anyways. The pill only prevents pregnancy.
    °☆*☆☆°The More You Know ☆°☆

  13. There are quite a few cytochrome p450 inducers including another TB drug, some seizure drugs, antipsychotics and antivirals…

  14. I once asked a nurse if I needed a different method of birth control after being prescribed an antibiotic for a UTI. He responded, "You could just say 'No'." I was asking a question about drug interactions not requesting commentary on my sex life. I'm still upset that I didn't file a complaint regarding it. I was young and so taken aback that I didn't know what to do.

  15. Sure, but whenever I take antibiotics (any kind) I get my period the next day as if I stopped taking my birth control pills (which I don't) so I won't be taking any chances

  16. I take testosterone with my progestin. Testosterone is far more effective with shutting down the reproductive system, it’s pretty awesome. Plus the other perks of testosterone in place of estrogen: decreased risk of breast and reproductive cancer cuz extra estrogen is a cancer magnet unfortunately.

  17. What i wanna know is why girls get weird and change when they get those pills. Its like an evil twin from another world replacing the people we love lol

  18. It's not an official interaction but we're still taught to counsel for it since there's lots of reports of cycle disruption even if it doesn't result in pregnancy.

  19. i misheard "right into your youtube feed" as "right into your uterus" for a second and i almost died choking on my food laughing so hard

  20. Contraceptives are the scourge of the modern world. We sacrifice family life of comforts for consumerism. Big farma have persuaded everyone that taking hormones that evidently cause a whole range of diseases starting from cardiovascular to obvious psychological to cancer in order to prevent your body from performing it's natural duty and had the audacity to call it freedom of choice. The only thing worse than that is abortion. On the other hand we condemn the men who take testosterone or other anabolic analogues and yes we tell the women that doing the same is ok or even preferable to normal state. Normal being able to naturally conceive children. Talk about double standards…. As a medical professional, as someone who unfortunately had the chance to resuscitate a young person who had pulmonary embolism and to my horror that person died under my arms I have refused to either prescribe oral or any kind of contraception or take participation in abortion. That is my both human and medical stance.

  21. I have a 25 year old son because I took an antibiotic with brith control. They didn't include any information or warning labels back then. You had to ask the pharmacist to get the information for you so very few people would bother finding out about the medication the doctor prescribed. My son was born 8 years after my last child and there was no other explanation for the pills failing. Boy was I surprised!

  22. It's weird because I'm from Europe and I was never told that I should use another contraceptive while being on antibiotics

  23. My son is living proof that you're wrong, and I'm sure he's not the only one Be careful of making a claim that only one data point can refute.

  24. This is good to know, but you should always pair your contraception with condoms. Birth control does not protect against STIs including HIV. Have safer sex, everyone! ^^

  25. When I had to take antibiotics last year, I ended up getting an extra “period”, which seems to indicate that my birth control (or period control in my case) was affected.

  26. What will the heat from the fires in the Amazon do to weather patterns over the nearby Atlantic Ocean/ Carribean? Could all of this added heat and pollutants cause higher rates of tropical storms or hurricanes?

  27. Thank you for making videos about these kinds of subjects. They’re most people’s only source on this kind of information

  28. Birth control causes endometriosis. Read the back, look it up, actions have consequences, "receiving due penalty for their error" is written in the Bible describing what happens when you go away from God's design, same is true with any std, consequences for immorality

  29. I remember reading that we should indeed use backup BC if we use antibiotics ( and this was also the advice for alcohol) because the BC would become less effective. That was a decade ago. I haven't seen those warnings about using backup BC when using antibiotics in years.

  30. What's the deal with antibiotics? I mean is it not effective if you take probiotics?

    What's the deal with birth control? I mean if you take it does that mean you can choose when you give birth?

    What's the deal with airline food?

  31. But it’s that one out of the thousands of others is the reason that say what they do on the birth control pills!! They don’t know if your taking that particular antibiotic!!

  32. One of the main side effects of antibiotics is nausea and vomiting which are due the damaging of the gut bacteria that are themselves included in the pill metabolism…reason why you could get pregnant…and then the example of enzymatic induction of rifampin could happen with all medicines this is why you should avoid taking lot of drugs in the same time…

  33. Antibiotics can bind to other stuff in the stomach. And some more than others, they can occupy the liver enzymes enough (or interact to make them weaker or stronger) that other drugs don’t get processed properly. And yes, antibiotics kill gut flora too.

  34. At my most recent contraceptive appointment the nurse told me that from now on antibiotics won't affect my birth control – interesting that a month later you make this video.

    And of course, the bieth control talked about here doesn't protect from STIs so still a good idea to use a condom.

  35. You know, it's actually pretty amazing when you think about it. We create all these medications and chemicals, swallow or inject them, and our bodies just go, "Okay, I know what to do with this." And voila, we're good. Now if only we could get our computers to that point.

  36. The CYP 450 liver enzyme pathway effects much more than just birth control.

    It effects how many medications are metabolized, including but not limited to opioids. This results in about 20% of the population not having any noticeable effect from some and severely limited pain relief at best from many other pain medications thus requiring significantly higher doses than would be considered "normal" and can cause an increase in the clearance rate to the point of normal routine testing seeming to indicate non-compliance with pain management prescription regimes.

  37. Is this a thing with steroids? I'm taking steroids for an inflammation thing and I'm on the placebo week and I haven't had my period yet.

  38. Of course, if you've got a bug which needs antibiotics, you may be sick and throw up the tablet, but if you're that bad, why would you have sex? Whether there is any truth in this one a wide-scale isn't really a problem. Use a condom as well. The pill will help keep you from getting pregnant but it does nothing for keeping STDs away. If you're active and don't have a regular partner, use a condom no matter what you use otherwise, ladies, 'cause he ain't going to tell you if he's got something wrong! (And he may not even notice if he has something like chlamydia. You don't want that… It's a koala killer!)

  39. Is it true for alcohol? Supposedly having alcohol makes your body try to process faster, so it in turn process your birth control pills faster. Therefore, especially if you've had a few and you're going to grt down to business towards the end of your 24 hour pill window, you should use a backup method.

  40. As a pharmacist, thank you for getting this right! But you will still hear the warning to use back up protection while taking antibiotics from pharmacists because they don't want to be the one in (10,000? 100,000? 1,000,000?) that tells a patient that they don't need to use back up protection and end up paying child support for 18 years. I don't know if it has really happened or is just an urban pharmacy legend, but I'm not taking any chances!

  41. Birth control causes breast cancer and hormones are urinated out but not filtered by our water system so we drink it up in rap water. Male orcas started lactating because of this..

  42. Let's do the math 🤓 Birth control fails 1 out of 10 times. That's 10%. Let's assume the US population is 300 million and that u.s. is 50% female. That's 150 million women. Assume half are in reproductive years, that's 75 million. Let's say less than half those women use hormone birth control pills, that's 35 million women. 10% failure of 35 million is 3.5 million women. I guarantee you there's at least 10% of that failure rate is women that just can't read/follow instructions, and that number is 350,000!!!! 🤔🤔🤔

  43. The problem is the phrase, “in theory”. Historically, science failed to study the female model.

    Today, even if scientists have changed their tune, and want to pursue female studies, there seems to be no funding.

    I can’t trust anything a scientist or doctor says, because, “in theory” could mean anything.

  44. CYP450 doesn't catalyse glucuronidation… it's a core (coenzyme) of oxidative enzymes, so it catalyses oxidation of active estrogen into inactive oxidized metabolites

  45. My wife found out the hard way. Tetracycline canceled the effect of the pill and she ended up giving birth to a daughter out of wedlock with a man she had already broken it off with. The pill is simply not 100% effective.

  46. Well they could always do a study on it. But, if they follow the common model of medical researchers I am doubtful that it would show any results. It's unlikely that middle-aged white men are going to get pregnant whether taking birth control and/or antibiotics. Unfortunately, these seem to be the only humans who matter in medical studies.

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