5 Times Medieval Medicine Accidentally Got it Right

Even if they had no idea how or why it worked...

We tend to think of medieval and ancient medicine as leeches, prayers, and Latin incantations, but every now and then, an intrepid barber-surgeon snuffed out a truffle.

While most treatments back then were about as effective as waving a chicken over your head (yes, that was a real thing), a few old-school remedies accidentally stumbled into something close to useful.

Here are five times medieval “doctors” kinda, sorta got it right—by accident.

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1. Bloodletting for Hemochromatosis and Polycythemia

They thought blood was one of the “four humors” and that too much of it made you… moody? Warm? Unbalanced?

So naturally, the solution was to drain you like a radiator.

Ridiculous, right? Well… unless you have hemochromatosis (iron overload) or polycythemia vera (too many red blood cells).
In both cases, therapeutic blood removal is actually a standard treatment today.

It’s not about humors—it’s about too much iron or too-thick blood. So yes, the medievals misunderstood the why, but were not totally wrong about the what.

Now the when is an entirely different matter. Bleeding you when they can’t think of anything else to do is wildly harmful. See: George Washington’s death from 40% blood loss.

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2. Trepanation (A.K.A. Drilling Holes in Your Head)

Ancient and medieval physicians drilled literal holes in people’s skulls to “release evil spirits” or treat headaches and seizures.

In fairness: horrific. Barbaric. Nightmare fuel.

But today, neurosurgeons do something very similar in emergencies—called a craniotomy—to relieve pressure from bleeding in the brain.

Did medieval docs understand intracranial pressure? Nope. But weirdly enough, their solution wasn’t entirely off-base. They just didn't have MRIs—or somewhat importantly, anesthesia.

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3. Leeches (Yes, Seriously)

Leeches were medieval medicine’s Swiss Army knife. Fever? Leeches. Sadness? Leeches. Unruly wife? Probably leeches.

But in modern medicine, we still use leeches in microsurgery to help restore blood flow to reattached fingers, ears, and skin flaps. Their saliva contains anticoagulants, which prevent clots and encourage healing in delicate tissues.

So... leeches weren’t useless. Just haphazardly overprescribed.

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4. Herbal Remedies That Actually Work

Monks and apothecaries kept extensive records of herbs for healing, some of which turn out to be effective:

• Willow bark (used for pain) contains salicin—a compound chemically similar to aspirin.

• Foxglove (used for dropsy, now known as heart failure) contains digitalis, a heart medication still used today (in carefully controlled doses... unlike the “handful and a prayer” method of the 1300s).

So, score one for the monastery gardens.

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5. Fasting as a Cure-All

Medieval doctors often prescribed fasting—not just for religious reasons, but for “cleansing” and “rebalance.”

They didn’t know about insulin, autophagy, or metabolic syndrome—but modern research shows that intermittent fasting and caloric restriction can support metabolic health, reduce inflammation, and even improve longevity.

Of course, they weren’t trying to biohack. They were trying to please God and avoid leprosy. But hey—credit where credit’s due.

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🏁 The Bottom Line?

Medieval medicine was mostly guesswork, superstition, and a whole lot of bleeding patients who probably needed hydration more than a hole in the skull. They made a lot of mistakes, for sure, and violated the Hippocratic oath willy nilly.

(Arguably, modern doctors leave a lot to be desired against the Hippocratic oath as well, but that is for another blog post…)

Ancient and old school doctors did a lot of harm in fascinating and creative ways, for sure. But every so often, they stumbled into something oddly adjacent to real science.

Let’s just be glad we live in an era where at least surgery doesn’t involve a rusty knife/saw, copious amounts of alcohol and a leather strap to bite down on.

And consequently low survival rates.