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What Causes Antibiotic-Associated Diarrhea? - Incheon Baekrokdam Haniwon
Blog June 1, 2025

What Causes Antibiotic-Associated Diarrhea? - Incheon Baekrokdam Haniwon

Dr. Yeonseung Choe
Dr. Yeonseung Choe
Chief Director

“Diarrhea Is Just the Beginning – Antibiotics, the Gut, and What We’ve Missed”

Hello. This is Baengnokdam Korean Medicine Clinic.

Have You Ever Experienced This?

You took cold medicine for a few days,
then suddenly, diarrhea starts.
At first, you don't think much of it.
‘Maybe I have indigestion.’
‘Could my gut be sensitive because I’m tired?’
But after a few days, the diarrhea doesn't stop,
and you continue to experience abdominal distension, burping, strange bowel sounds, and a feeling of incomplete evacuation.
In severe cases, some even develop a fever and are truly stuck in the bathroom.
Is this just simple enteritis?
No. This could be a sign that your gut has been compromised by antibiotics.

How Antibiotics Changed Our Bodies

In the 1940s, when penicillin was first developed,
it was humanity’s first weapon against bacterial infections.
Pneumonia, sepsis, tuberculosis, gonorrhea...
The mid-20th century was the "Age of Antibiotics."
No one thought antibiotics were a problem.
They were life-saving drugs.

Strange Diarrhea, Unexplained Deaths

However, as time passed,
an increasing number of patients began to experience unusual diarrhea after taking antibiotics.
Especially among hospitalized patients, the elderly, and critically ill patients,
cases of diarrhea, high fever, abdominal pain, and even death began to emerge.
At the time, no one knew the cause.
Infection? Or an immune reaction?

1978 – Evidence That Antibiotics Damage the Gut

In 1978, Dr. Bartlett’s team in the United States
identified the cause as toxins A and B produced by the bacterium Clostridioides difficile.
They discovered that when antibiotics are used, beneficial bacteria living in the gut disappear,
allowing C. difficile to explosively proliferate in the vacant niche.
Furthermore, the toxins produced by this bacterium destroy the intestinal mucosa,
forming a yellow membrane called a pseudomembrane and causing fatal inflammatory diarrhea.
From this point on, antibiotics began to be recognized as both a 'cure' and an 'ecosystem destroyer'.

AAD, PMC – The Other Side of Antibiotics

Today, we call these side effects Antibiotic-Associated Diarrhea (AAD).
At least 5%, and up to 25%, of people who take antibiotics experience diarrhea.
And some of them can progress to a fatal condition called Pseudomembranous colitis.
This can involve dozens of bowel movements per day,
suffering from abdominal pain, the intestinal lining being shed,
and in severe cases, intestinal perforation, leading to shock and death.

Antibiotics Kill All Bacteria – Even Good Ones

We think of antibiotics as 'drugs that kill infectious bacteria'.
However, antibiotics do not distinguish between good and bad bacteria.
Trillions of beneficial bacteria responsible for digestion, absorption, immunity, and even emotions in the gut
are all wiped out by a few antibiotic pills.
As a result, the intestinal lining thins,
inflammation persists, digestion is impaired,
and even emotions become unstable.

How Is Antibiotic Prescription Changing?

In the past, antibiotics were prescribed quickly, strongly, and for prolonged periods without exception.
But now, things have changed.
The approach is to precisely identify the infectious agent and, when necessary,
use the narrowest possible spectrum for the shortest possible duration.
Furthermore, the recovery of the gut microbial ecosystem is now included in the treatment plan.
This is what we now call Antibiotic Stewardship.

But We Still…

So, what about our current reality?
Still, for common colds, gastritis, and rhinitis, broad-spectrum antibiotics are often empirically prescribed without proper testing.
Patients demand antibiotics,
and doctors prescribe them without time for explanation.
Consultations have become faster, but the gut ecosystem is being destroyed at the same pace.

Diarrhea Is Just the Beginning

If you experience diarrhea after taking antibiotics,
it might not be just a simple gastrointestinal reaction,
but a sign that your gut ecosystem is collapsing.
Stopping diarrhea doesn't mean it's over.
If symptoms like abdominal distension, bowel sounds, burping, incomplete evacuation, indigestion,
and alternating constipation and diarrhea persist afterwards,
it means your gut has not yet recovered.

Antibiotics Are Not Necessarily Bad Drugs.

However, there is a price to their effectiveness.
The gut microbiota is fundamental to our body's immunity, digestion, and emotions.
When that balance breaks down, the body silently collapses.
When using antibiotics, it's crucial to consider necessity, duration, scope, and recovery together.
Your gut is an ecosystem.
Antibiotics might destroy it,
but ultimately, protecting it can also be your choice. Thank you.

#AntibioticSideEffects #AntibioticAssociatedDiarrhea

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Dr. Yeonseung Choe

Dr. Yeonseung Choe Chief Director

I have met many patients who came after visiting multiple medical institutions and departments for persistent or recurrent conditions. Symptoms normally handled by different specialties—such as abdominal pain, headaches, palpitations, dizziness, and insomnia—may overlap in one person. Sometimes there is no clear improvement despite taking medication for each symptom, and being unwell gradually becomes part of daily life. In these cases, I look beyond individual diagnoses and examine how the symptoms connect and change together. Asking only about the most uncomfortable symptom today does not reveal the full course. I look at when the body first began to change and what happened after illness, surgery, childbirth, or starting and stopping medication. I also review changes in weight, diet, and sleep, then trace which symptoms improved with previous treatment and which remained. Test results, diagnoses, and the course of previous treatment are important for understanding the current condition. Clinical research in modern Korean medicine, physiological and pathological research in modern medicine, and observations recorded in classical Korean medicine texts offer different perspectives on the same body. Rather than fitting a patient into one perspective, I consider what each can and cannot explain and look for clues that connect symptoms and treatment histories that were previously considered separately.

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