Did You Know Antibiotics Can Change Your Estrogen Levels?

As I passed the time at home, waiting to feel better, I remember reading the potential side effects on the bottle of antibiotics: “may result in rash or nausea.” But as I’ve learned more about why I was getting so sick and what antibiotics actually do, I’ve found that caveat fails to fully encompass what many individuals, specifically women, experience when it comes to antibiotics.

Modern medicine is an amazing thing – but far too often, we learn after the fact that the very thing that’s been prescribed to make us better has done more than that (and not in a good way). Antibiotics are no exception, and that’s because they can be responsible for significant fluctuations in estrogen levels.

How Is This Possible?

If you recall your high school biology class, antibiotics are a type of antimicrobial compound designed to kill off or stop the growth of bacteria. There are different classes of antibiotics. Some are used for a broad spectrum of purposes, while others are more specialized to target specific bacteria, but most are used to treat bacterial infections like strep throat, urinary tract infections, and skin conditions. When you picture antibiotics, you might think of an oral pill or topical treatments. Both basically work in the same way (targeting bacterial cells to keep them from growing and spreading), even if they’re administered differently.

As I’ve discovered from chronic tonsillitis, most antibiotic side effects upset the gastrointestinal system and result in things like diarrhea, stomach cramps, nausea, and even vomiting. But many women who are prescribed antibiotics are often advised that the treatment may interfere with their hormonal birth control. Depending on the woman, estrogen levels may increase or decrease, and ovulation may even be suppressed or delayed.

Certified Women’s Health Coach and hormone expert Nicole Jardim explains that both antibiotics and hormones like progesterone and estrogen are metabolized in the liver. If antibiotics are taken during the first half of your cycle when estrogen is on the rise, the antibiotics may speed up the liver’s metabolization of the estrogen, meaning there’s not enough estrogen left in the bloodstream to use for ovulation. If this happens before ovulation occurs and there’s insufficient estrogen, the woman will naturally experience an anovulatory cycle (absence of ovulation during a cycle) or delayed ovulation. 

Consistent antibiotic use has been linked to developing allergies and inflammatory bowel disorders.

If you’re on hormonal birth control, a lack of synthetic estrogen from your birth control may cause you to ovulate, rendering your birth control useless. One study published in 2017 discovered that a class of antibiotics called rifampicin (used to treat serious illnesses like meningitis and tuberculosis) caused spontaneous ovulation in women using oral contraceptives, patches, and implants. Birth control failure, as most of us know, can result in pregnancy or, at the very least, a further complicated jumble of your already confused hormones. 

Because antibiotics might result in diarrhea or other GI issues, the estrogen speedily leaves the body, having been metabolized and excreted too quickly for the body to use it. Hormones are a delicate dance of biology. One unintentional step made without all the information can throw the body out of kilter, as several women learned unexpectedly.

Real-Life Experiences

It’s one thing to read about a significant side effect of such a common prescription – it feels far removed to most of us. But for those who have experienced it, this often undisclosed consequence affected them in unpredictable ways.

Senior Evie editor Paula Gallagher knows this firsthand. She contracted strep throat and was prescribed amoxicillin, as is normal for a bacterial infection. Paula began her antibiotics a few days before ovulation, but the blood work she got back on the last day of her prescribed routine was anything but ordinary. Both her estrogen and progesterone were significantly lower than usual. “Prior to this test,” she tells me, “both my levels were healthy. The super low estrogen was extra weird because I’ve never had a problem with dramatically low estrogen before.”

Paula was never told by any of her medical providers that the antibiotics she was taking could potentially tank her hormones – it took the internet and her own savvy intuition for her to confirm she was likely experiencing this as a side effect. Thankfully, her levels were back to normal a few weeks later at her next routine blood test.

Another individual I spoke with, Megan, also had strep throat but was prescribed cefdinir, a different antibiotic. Megan is a new mom who breastfeeds exclusively, whose fertility hasn’t returned yet, and who tracks her estrogen and luteinizing hormone every day. During her round of antibiotics, she noticed that her estrogen levels were lower than normal and also experienced breakthrough bleeding, a telltale sign of low estrogen. Because Megan’s levels frequently fluctuate due to breastfeeding, her low levels caused her some confusion – until she learned the cefdinir was likely responsible.

I also spoke with Alexa, who was prescribed amoxicillin for an infection. She soon began experiencing routine symptoms of low estrogen, like hot flashes, fatigue, and severe PMS. After doing blood work, she learned that both her estrogen and progesterone levels were lower than normal. Alexa did some research to balance her hormone levels, and decided to also complete blood work for her next cycle to verify that the amoxicillin was responsible.

It’s natural to surmise that symptoms like fatigue, headache, and even a late, early, or missed period could all be related to being sick or stressed. And, if we have no concrete evidence from blood work, that’s what we’re led to believe. It’s interesting that antibiotics – the most common treatment we often seek for strep throat or other infections – routinely top the charts of the most prescribed class of medication globally, generating billions of dollars in revenue. It’s entirely possible that we’re never told about its more significant, troublesome side effects that these women experienced for that very reason. 

Getting Back to Normal

A disconcerting effect of studying antibiotics and their interference with hormones is that many sources claim the only evidence backing this connection is circumstantial. Women are encouraged not to ignore their bodies, yet they’re simultaneously told by the medical establishment at large that the outcome of a routine medicine isn’t agitating their bodies the way they think it is, even when women take the initiative to find clear and convincing proof to the contrary. 

Women are encouraged not to ignore their bodies, yet they’re simultaneously told by the medical establishment that a routine medicine isn’t agitating their bodies the way they think it is.

When our hormones are temporarily imbalanced, for whatever reason, the natural solution is to balance them back to their functioning, healthy levels in whatever way we can. Because antibiotic use can wreck your gut (in the process of killing bad bacteria, it can also destroy good bacteria), it’s essential to invest in prebiotics and probiotics to counteract the antibiotic’s effects. Consistent antibiotic use has been linked to developing allergies and inflammatory bowel disorders, so it’s key to mitigate those symptoms in any way you can.

It’s also beneficial to drink bone broth, eat fermented foods (like kimchi) to repopulate gut flora with good bacteria, and to eat fiber-rich foods, says Nicole Jardim. It’s also worth looking into different vitamins to supplement your body and replenish your stores if you’re on hormonal birth control. 

Most of all, listen to your body. In the course of an antibiotic prescription, symptoms like hot flashes, fatigue, headache, and lack of concentration – in addition to the more physical side effects of the antibiotic – might lead you to think you’re entering perimenopause, or even that you’re pregnant. While larger issues are always a possibility, it’s also likely that the antibiotic is interfering with your hormones, as so many have experienced. Additionally, encourage your medical provider to be honest with you. Ask them about the treatments they’re prescribing you, and even if there are available alternatives, if you have specific concerns about antibiotic regimens.

Closing Thoughts

Everything from foods to cosmetics to the synthetic-material clothes we wear has the ability to interact with our hormones. Antibiotics are no different, though their widespread use and reliance are often directly equated to their safety. Every woman, every body, every illness, and every treatment is unique and distinct, but it’s time that we acknowledge that just because something is commonly prescribed doesn’t mean it won’t negatively affect us in any way.

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