Perth, Australia. 1982. A young gastroenterologist named Barry Marshall was looking at something that shouldn’t exist.
Under the microscope, in biopsies taken from patients with stomach ulcers, he kept seeing the same thing: curved, spiral-shaped bacteria colonizing the stomach lining.
This was impossible. Everyone knew bacteria couldn’t survive in the stomach. The gastric acid was too strong—pH of 1.5 to 3.5, strong enough to dissolve metal. Medical textbooks stated definitively: the stomach is sterile.
But the bacteria were there. Marshall could see them.
His colleague, pathologist Robin Warren, had been noticing the same bacteria for months in biopsy samples. He’d mentioned it to other doctors. They’d dismissed it as contamination or misidentification.
But Marshall and Warren weren’t seeing contamination. They were seeing a pattern. Nearly every patient with gastric ulcers had these spiral bacteria. Patients without ulcers rarely had them.
They formed a hypothesis: What if these bacteria caused stomach ulcers?
The medical establishment’s reaction was swift and brutal: You’re wrong. That’s ridiculous. You clearly don’t understand basic gastroenterology.
In the early 1980s, the cause of stomach ulcers was settled science. Everyone knew what caused them:

Stress – Type A personalities, anxiety, high-pressure jobs
Spicy food – Hot peppers, acidic foods
Excess stomach acid – Genetic predisposition to acid production
Lifestyle – Smoking, alcohol, irregular eating

The treatment was equally well-established: antacids, acid-suppressing drugs, bland diets, stress management. If those failed, surgery—cutting part of the stomach or severing the vagus nerve to reduce acid production.
Ulcers were considered a chronic, recurrent condition. Patients managed them for life. Pharmaceutical companies made billions selling acid reducers. Surgeons performed thousands of ulcer operations annually.
And two doctors in Australia were saying: It’s bacteria. We can cure it with antibiotics.
The response from the medical community was dismissive, sometimes hostile:
“If you’re right, why hasn’t anyone else found this in 100 years of gastroenterology?”
“Bacteria can’t survive stomach acid. Basic biology.”
“This is two unknown researchers trying to make a name for themselves with a crackpot theory.”
Marshall and Warren tried to publish their findings. Journals rejected them. They presented at conferences. Audiences were skeptical at best, contemptuous at worst.
They tried to prove their theory using animal models—infecting mice, pigs, rats with the bacteria to show it caused ulcers.
It didn’t work. The bacteria, which they’d now identified as Helicobacter pylori, only infected primates. And ethical guidelines made human trials extremely difficult to approve for an unproven theory.
Marshall was stuck. He had a theory he believed was correct. He had observational evidence. But he couldn’t prove causation, and without that proof, the medical establishment would never accept it.
So in 1984, Barry Marshall did something that was either brilliantly desperate or completely insane, depending on your perspective.
He decided to infect himself.
Without formal ethical approval. Without telling the hospital ethics committee. He told his wife—who was horrified—but proceeded anyway.
Marshall went to the lab and prepared a culture of Helicobacter pylori taken from a patient with severe gastritis. He grew it in a petri dish until he had a concentrated bacterial soup.
Then, on an empty stomach, he drank it.
He later described it as tasting “like swamp water.” He consumed billions of live bacteria that supposedly couldn’t survive in the human stomach.
Then he waited.
For two days, nothing happened. Marshall began to worry his self-experiment had failed—that maybe his own stomach acid had killed the bacteria, or that he was naturally immune.
On day three, he started feeling sick.
By day five, he was violently ill. Nausea. Vomiting. His wife noticed his breath had become unbearably foul—a symptom later associated with H. pylori infection.
Ten days after drinking the bacteria, Marshall underwent an endoscopy—a camera inserted down his throat to examine his stomach.
The results were undeniable.
His previously healthy stomach lining was inflamed, red, and swollen. He had developed acute gastritis. Biopsies showed his stomach was colonized with Helicobacter pylori—massive amounts of the bacteria that “couldn’t survive” in stomach acid.
Marshall had proven that the bacteria could colonize a healthy human stomach and cause disease.
But he wasn’t done yet. He still needed to prove these bacteria caused ulcers, not just gastritis, and that antibiotics could cure the condition.
He treated himself with antibiotics and bismuth (Pepto-Bismol contains bismuth, which has antibacterial properties). Within weeks, his symptoms disappeared. Follow-up endoscopy showed his stomach had healed. The bacteria were gone.
He had infected himself, made himself sick, and then cured himself. The entire experiment, from infection to cure, was documented with biopsies and photographs.
It was one of the most dramatic self-experiments in modern medical history.
And the medical establishment still didn’t believe him.
Journals remained skeptical. Critics argued that gastritis wasn’t the same as ulcers, that his experiment was uncontrolled, that correlation wasn’t causation.
But Marshall and Warren kept fighting. They published case studies. They documented successful antibiotic treatment of ulcer patients. They showed that eradicating H. pylori prevented ulcer recurrence—something acid-suppressing drugs couldn’t do.
Slowly, grudgingly, the evidence became impossible to ignore.
By the early 1990s, the medical consensus began to shift. Studies from multiple countries confirmed Marshall and Warren’s findings. The National Institutes of Health issued a consensus statement in 1994: Helicobacter pylori causes most stomach ulcers and should be treated with antibiotics.
The revolution was complete. Within a decade, ulcer treatment had fundamentally changed:
Before: Lifelong acid medication, dietary restrictions, sometimes surgery
After: Two weeks of antibiotics, permanent cure for most patients
Ulcer surgery rates plummeted. Chronic ulcer disease nearly disappeared. Millions of people were cured of a condition they’d been told was incurable.
Pharmaceutical companies lost billions in antacid sales, but overall healthcare costs dropped dramatically—curing patients is cheaper than managing them forever.
And in 2005, twenty-one years after Barry Marshall drank a petri dish of bacteria, he and Robin Warren were awarded the Nobel Prize in Physiology or Medicine.
The Nobel Committee’s citation stated: “Their discovery has led to a revolutionary change in the treatment of peptic ulcer disease and has improved the quality of life for millions of people.”
It’s one of the most remarkable vindication stories in modern science.
Two researchers, working at a hospital in Perth—far from the prestigious medical centers of America and Europe—overturned 100 years of medical consensus.
They were ridiculed, rejected, dismissed as cranks. They couldn’t get published in major journals. They couldn’t get funding. The entire weight of established medicine said they were wrong.
And they were right.
Marshall’s self-experiment was ethically questionable by modern standards—no institutional review board would approve it today. It was dangerous. It could have caused permanent damage or worse.
But it worked. It provided proof that couldn’t be dismissed. It forced the medical establishment to confront evidence they’d been ignoring.
Barry Marshall is often asked if he regrets the self-experiment. His answer: “Not for a second.”
He had tried everything else. He’d followed proper channels. He’d submitted papers, given presentations, proposed studies. All rejected.
The self-experiment was a last resort—but it was the thing that finally broke through decades of dogma.
The story reveals something important about how science actually progresses.
We like to think science follows evidence, that good ideas triumph through rational debate and careful experimentation.
But reality is messier. Scientific consensus can become entrenched. Established researchers protect their turf. Journals prefer papers that confirm existing theories. Pharmaceutical companies have financial interests in maintaining the status quo.
Revolutionary ideas—even correct ones—face enormous resistance.
Thomas Kuhn called this “paradigm shift”: the painful, slow process by which scientific communities abandon old theories for new ones. It’s rarely smooth or rational.
Marshall and Warren’s discovery should have been accepted within months. The evidence was clear. The implications were enormous.
Instead, it took over a decade of fighting, plus a dramatic self-experiment, plus mounting evidence from multiple countries before the medical establishment admitted it had been wrong for a century.
How many other correct theories are being dismissed right now because they challenge consensus? How many researchers are being ignored because their ideas sound crazy?
Marshall’s story doesn’t mean every outsider with a wild theory is right. Most aren’t. Scientific consensus exists for good reasons—most challenges to it are wrong.
But sometimes—rarely, but sometimes—the crazy idea is correct. And when that happens, we need scientists brave (or stubborn) enough to keep fighting when everyone says they’re wrong.
Barry Marshall was stubborn enough to drink bacteria.
He made himself violently ill to prove a point.
He endured ridicule, rejection, and years of professional isolation.
And because he refused to give up, millions of people were cured of a disease they’d been told was incurable.
Today, Helicobacter pylori infection is recognized as the cause of most stomach ulcers, many cases of gastritis, and some stomach cancers. Testing for and eradicating the bacteria is standard medical practice worldwide.
The bacteria that “couldn’t exist” in the stomach is now one of the most well-studied pathogens in medicine.
And Barry Marshall, the gastroenterologist who was told he didn’t understand basic biology, has a Nobel Prize sitting on his shelf.
Sometimes being right isn’t enough. Sometimes you have to be willing to drink the bacteria to prove it.