How Antibiotics Threaten Your Health and Your Gut

How Antibiotics Threaten Your Health and Your Gut

Infectious bacteria cause all sorts of illnesses—from food poisoning to tuberculosis. Antibiotics are a group of antimicrobial drugs that either kill or stop the spread of these harmful bacteria.

“…antibiotic-resistant bacteria kill tens of thousands of Americans every year. Those numbers seem poised to go way up”.

While we depend on these drugs for lifesaving medical purposes, the more we use them, the more the bacteria they target are likely to develop successful defenses. This is known as resistance. Already, antibiotic-resistant bacteria kill tens of thousands of Americans every year. Those numbers seem poised to go way up.

“By 2050, the rough estimate is that 10 million people will die each year of resistant bacteria, which could make it the number one killer in the world—greater than cancer,” says Gautam Dantas, PhD, a professor of pathology and immunology at Washington University School of Medicine in St. Louis.

By 2050, the rough estimate is that 10 million people will die each year of resistant bacteria, which could make it the number one killer in the world—greater than cancer,” says Gautam Dantas, PhD, a professor of pathology and immunology at Washington University School of Medicine in St. Louis. Dantas says the development of resistance is unavoidable; it’s part of the natural evolutionary dance between living microorganisms. But it’s speeded up by the unnecessary use of antibiotics and other antimicrobials.

“…up to 50% of the antibiotics prescribed in outpatient settings …is inappropriate, meaning the antibiotic given was too powerful or unlikely to do a person any good.”

A lot of our current use is unnecessary. According to recent figures from the Centers for Disease Control and Prevention, up to 50% of the antibiotics prescribed in outpatient settings—doctor’s offices, walk-in clinics, etc.—is inappropriate, meaning the antibiotic given was too powerful or unlikely to do a person any good.

Dantas says this sort of inappropriate use happens in part because many doctors falsely assume that these drugs have no downsides. “They think if there’s even a tiny chance the drugs may work, they are worth prescribing, because there’s no harm done if they don’t work,” he says, summarizing the faulty reasoning.

“…we’re rocketing toward a future where more and more pathogenic bacteria are not going to be treatable with existing antibiotics”.

Meanwhile, because it is not lucrative, private sector interest in discovering or developing new antibiotics is scant. Some governments and non-profit groups are trying to fund research to identify novel antibiotics or treatments for resistant bacteria. But at the moment, we’re rocketing toward a future where more and more pathogenic bacteria are not going to be treatable with existing antibiotics.

An increasingly possible scenario, one expert I interviewed told me, is that we end up back in a world where children die of scraped knees or young women die of untreatable urinary tract infections.

As far as imminent threats to human health go, I would put antibiotic resistance second only to global warming,” says Lance Price, PhD, a professor of environmental and occupational health at George Washington University and president of GW’s Antibiotic Resistance Action Center.


Resistance is only one of the problems posed by unnecessary antibiotic use. Even when these drugs are warranted, such as in cases of an illness-causing bacterial infection, Dantas says that taking them may still be risky.

For a first-of-its-kind study published last month in the journal Cell Reports, he and his colleagues found that antibiotics can cause lasting disruptions to the guts of healthy people.

“Antibiotics can kill bacteria indiscriminately, and so they often take out good gut microbes along with the bad.”

The gut microbiome is a community of trillions of microorganisms that play a crucial role in digestion, immune functioning, and many other vital health processes. Antibiotics can kill bacteria indiscriminately, and so they often take out good gut microbes along with the bad. “As soon as you give an antibiotic, diversity dives and abundance crashes,” Dantas says.

Drops in microbiome diversity and abundance are associated with all manner of GI dysfunction, including inflammatory bowel disease. Historical data show that IBD is far more common now than it once was, and doctors who study the condition say the overuse of antibiotics may partly explains its rise.

Fortunately, Dantas’s study found that the microbiomes of healthy people tend to bounce back following these temporary post-antibiotic depletions. But sometimes they don’t.

Six months after their antibiotic course, three of the 20 people in his study still showed signs of major gut imbalances. “They appeared to move much closer to the dysbiotic microbiomes we observed in people in the ICU,” Dantas says. “This suggests that even if you’re healthy, taking antibiotics is a gamble every single time you do it.”

There are a handful of ways we could all reduce the risks posed by antibiotic overuse.

First of all, if you’re prescribed an antibiotic, Dantas says it’s worthwhile to ask one or two polite questions of your healthcare provider. “Just say, doc, can you please explain to me what you think is going on here and what infection are you trying to treat?” he advises.

A lot of antibiotics are given because doctors think their patients want them, he says. By asking questions or showing a disinclination to take an antibiotic, you may find that you have other options.

Especially if you’re prescribed an antibiotic at an urgent-care clinic and your provider has not taken any swabs or run blood tests to confirm that you have a bacterial infection, it may be worth getting a second opinion before carpet-bombing your gut with a powerful antimicrobial drug.

At a broader level, fighting back against the threat of antibiotic resistance is going to require policy action—and maybe changes in how we shop and eat.

“Antibiotics are often administered to livestock in order to keep them alive in brutally unhealthy conditions”.

Antibiotics are often administered to livestock in order to keep them alive in brutally unhealthy conditions. Just as antibiotic overuse in people drives up resistance, so does overuse in animals. A landmark program in Denmark’s pig and pork industry found that severely restricting the use of these drugs can lead to a measurable drop in resistant-bacteria infections in nearby human populations.

“Buying power is really important,” GW’s Price told me. He recommends buying meat products labeled “raised without antibiotics,” and asking for these products from restaurants and food suppliers. Already, growing demand from consumers has led fast-food giants like McDonald’s to make changes in the meat they buy, and this has a huge impact, he says.

He also urges us all to pressure our elected officials and federal authorities to better regulate antibiotic use and to fund programs that will lead to the development of new antibiotics. “This is something worth fighting for,” he adds. “We have a responsibility.”

The world has no shortage of problems. Prioritizing isn’t easy. But as with climate change, we know enough now about antibiotic resistance to recognize the urgency of our situation. If ignorance is bliss, knowledge can be a burden. Our response to these burdens has been to lay them down for future generations to carry. If we keep that up, it looks like our kids and grandkids—and maybe us too—will be crushed by their weight.


Markham Heid is a freelance health writer. His work has appeared in TIME magazine, The New York Times, and elsewhere. He’s a regular contributor at Elemental, a Medium publication, where an alternative version of this story first appeared.