What if the next major weapon against antibiotic-resistant superbugs wasn’t hidden in a high-tech lab—but in a 1,000-year-old medical manuscript?
As hospitals around the world grapple with infections that shrug off our most powerful drugs, scientists are looking in unexpected places for answers. One of the most promising? A 9th-century remedy made from garlic, onion, wine, and bile, recorded in an old English text called Bald’s Leechbook. Originally used to treat eye infections, this medieval mixture has just stunned researchers by killing up to 90% of MRSA—one of the deadliest antibiotic-resistant bacteria—in lab tests.
This isn’t folklore. It’s hard science. And it could change the way we think about both ancient medicine and the future of antibiotics.
The Antibiotic-Resistance Crisis
Antibiotics have saved millions of lives since their discovery, but their power is fading. Bacteria are evolving faster than we’re developing new drugs—and they’re winning. One of the most persistent threats is methicillin-resistant Staphylococcus aureus (MRSA), a type of staph bacteria that no longer responds to common antibiotics. It’s a frequent cause of serious infections in hospitals, nursing homes, and surgical wounds.
But MRSA is only one part of a larger—and growing—crisis. The World Health Organization has warned that we are heading toward a “post-antibiotic era”, where routine infections could once again become deadly. According to estimates published in The Lancet, over 1.27 million deaths worldwide in 2019 were directly caused by drug-resistant infections—with projections hitting 10 million deaths per year by 2050 if new solutions aren’t found.
What makes this even harder to combat are biofilms—dense bacterial communities that form on surfaces like medical devices, chronic wounds, and tissues. In a biofilm, bacteria become up to 1,000 times more tolerant to antibiotics compared to free-floating cells. That’s one reason chronic infections—like those in diabetic foot ulcers or surgical implants—are so difficult to treat. In the UK alone, biofilm infections are estimated to cost the NHS over £1 billion a year.
Despite the urgency, pharmaceutical companies have largely scaled back antibiotic development, in part because it’s expensive and low-reward financially. This has left a dangerous gap between rising bacterial resistance and the dwindling pipeline of effective drugs.
A Medieval Discovery That Stuns Scientists
The discovery came from an unlikely place: a 9th-century medical manuscript known as Bald’s Leechbook. Written in Old English and housed in the British Library, the book is one of the earliest known medical texts in Europe. Among its pages is a recipe for an “eye salve” meant to treat infections—hardly the place you’d expect to find a candidate for fighting modern superbugs.
But that’s exactly what researchers at the University of Nottingham and University of Warwick decided to test. The recipe called for equal parts garlic and onion (or leek), combined with wine and bile salts from a cow’s stomach. The ingredients were crushed, steeped, and left to ferment in the cold for nine days—following the original instructions as closely as possible.
Dr. Christina Lee, a specialist in Old English, translated the recipe. Microbiologist Dr. Freya Harrison led the lab effort to recreate it. Their initial aim was modest: to see if this medieval concoction might show a small degree of antibacterial activity.
What they found stunned them. In lab tests, the complete mixture wiped out up to 90% of MRSA bacteria in lab-grown biofilms. Not just free-floating bacteria—biofilms, the very structures that modern antibiotics often fail to penetrate. Even more remarkably, the effect disappeared when any single ingredient was removed. The remedy only worked as a combination.
The team tested dozens of batches using both onions and leeks, confirming that the recipe’s power wasn’t a one-off fluke. They also compared it to individual ingredients like purified garlic extract (allicin) and found that the full mixture was significantly more effective, especially in realistic infection models.
What the Lab Tests Showed About Bald’s Eyesalve
The lab testing of Bald’s eyesalve wasn’t just a quirky experiment—it followed rigorous microbiological protocols, and the results have been published in peer-reviewed journals. Over the course of several years, researchers prepared more than 75 batches of the remedy, using both onion and leek variants. Each batch underwent testing against dangerous pathogens, including strains from the ESKAPE group—the six most common antibiotic-resistant bacteria in hospital infections.
The standout result? The onion-based version (called ESO) consistently killed up to 90% of MRSA biofilms in synthetic wound models designed to mimic real human tissue. This wasn’t just a petri dish success. The team used collagen-based synthetic wounds at body temperature (37°C), closely simulating conditions inside infected soft tissue.
Importantly, the mixture showed broad-spectrum antibacterial activity, effectively wiping out both Gram-positive and Gram-negative bacteria in their planktonic (free-floating) form. But its real strength came through against biofilms, where most antibiotics fail.
ESO was able to eradicate mature biofilms of S. aureus, A. baumannii, and S. pyogenes, and significantly reduce biofilm counts for MRSA and S. epidermidis.
Researchers also broke down the recipe to test each component individually and in “dropout” versions missing one ingredient. None of the ingredients alone—including garlic or its main compound, allicin—had significant biofilm-killing power. Even garlic, which is known for its antimicrobial effects in standard lab broth, failed to work in the wound model unless combined with the other ingredients.
Interestingly, the allicin concentration in Bald’s eyesalve was lower than that used in purified form, yet it was more effective. That suggests a synergistic effect—where the whole recipe performs better than the sum of its parts. Ingredients like wine and bile, though weak antimicrobials on their own, may enhance compound extraction, penetration, or chemical activation in ways not yet fully understood.
The Future of Fighting Infections
Bald’s eyesalve isn’t just a quirky success story—it’s a serious contender in the search for alternative treatments to drug-resistant infections. In particular, its ability to disrupt biofilms, the fortified bacterial structures that make chronic wounds so hard to treat, could have real clinical impact. These infections aren’t rare: they show up in diabetic foot ulcers, surgical sites, burns, and implanted devices—and when antibiotics fail, the risks escalate quickly to sepsis, amputation, or worse.
Among the most promising applications is in diabetic foot infections, which microbiologist Dr. Freya Harrison calls the “ultimate, super-resistant biofilm infection.” These wounds often don’t respond to current antibiotics, and in severe cases, there’s little choice but to amputate. A topical treatment that can safely clear biofilms without damaging tissue would be a game-changer.
So far, early safety testing suggests the remedy doesn’t irritate skin or interfere with wound healing. Researchers are now working on identifying which chemical compounds within the mixture are responsible for its biofilm-killing activity, and how they interact. This step is critical—not only for understanding the mechanism, but also for paving a regulatory path toward clinical use.
That process won’t be fast. Testing natural remedies made of multiple active compounds is far more complex than evaluating a single synthetic drug. Still, the team is moving forward with chemical characterization, toxicity studies, and formulation work. Patch testing on human skin is also in the pipeline.
The Power of Natural Combinations
For many years, drug discovery has aimed to find and isolate one “active” ingredient. But what we’ve learned from this medieval remedy shows us something different: the real power of natural medicine might be in how ingredients work together. Think about garlic, for instance. Its main antibacterial compound, allicin, is well-known. However, in lab tests, allicin alone wasn’t enough to kill tough MRSA in biofilms. The full impact only happened when all four parts of Bald’s eyesalve—garlic, onion, wine, and bile—were combined and prepared under specific conditions.
This highlights the idea of synergy, where ingredients interact to create an effect far greater than any single one could achieve. This finding challenges our current drug development approach, which often overlooks complex natural mixtures in favor of simpler, single compounds that are easier to patent. This could mean we’re missing out on powerful treatment combinations, especially for complex issues like chronic infections.
What’s also clear is that old medical texts, like Bald’s Leechbook, might hold more scientific value than we previously thought. Researchers found that garlic and other similar plants were often paired together in the manuscript, suggesting medieval healers might have observed these combined effects themselves, even without understanding the science behind it. Of course, this doesn’t mean every old remedy works or is safe. But the success of this eyesalve proves that careful, evidence-based research into historical medicine can uncover valuable tools for today’s health challenges.
Making the Ancient Remedy: A Step-by-Step Look
When scientists decided to test this ancient remedy, they didn’t just guess at the ingredients. They went back to the original 9th-century text, Bald’s Leechbook, to follow the instructions as closely as possible. It wasn’t about making a modern version; it was about recreating the exact concoction from a thousand years ago.
Here’s what the original recipe called for and how they put it together:
- The Ingredients: They used equal amounts of garlic and onion (sometimes leek was used as an alternative, as the original text allowed for it). To this, they added wine and bile salts, which came from a cow’s stomach.
- The Process: The raw ingredients were first crushed. Then, they were steeped together in the liquid components. This mixture was then left to ferment in cold conditions for a full nine days. This fermentation step, done precisely as the medieval instructions stated, was crucial.
It’s important to understand that this wasn’t just throwing ingredients into a pot. The researchers meticulously followed these old instructions, down to the fermentation time and temperature, because they found that the remedy only worked effectively when all components were present and prepared exactly as described. This careful recreation allowed them to truly test the power of this ancient formula against modern superbugs.
Old Medicine, New Possibilities
This isn’t just about a medieval recipe working better than expected—it’s a warning that our current approach to antibiotics is no longer enough. While pharmaceutical innovation stalls, antibiotic resistance is accelerating. The discovery that a thousand-year-old remedy can kill MRSA biofilms highlights how much we still don’t understand—and how much we might be missing.
Bald’s eyesalve doesn’t offer an instant cure. It’s not a magic potion or a home remedy. But it proves a point: the tools we need may already exist, buried in overlooked traditions, natural compounds, or historical texts. What matters now is rigorous, open-minded research that challenges outdated assumptions and asks the right questions.
As we face a future where standard antibiotics may no longer protect us, the lesson is clear: the answers might not always lie in what’s new, but in how we rethink what we already have.
