Dear health-conscious friends,
Medicine has saved billions of lives.
But it didn’t get there without making some spectacular mistakes along the way.
Some treatments that once seemed perfectly reasonable would horrify a modern doctor. Others were based on ideas that survived for centuries simply because nobody thought to question them.
Here are some of the most famous medical mistakes in history — and the lessons they left behind.
1. Bloodletting: When Losing Blood Was Supposed to Make You Better
For centuries, doctors treated everything from fever and pneumonia to headaches by deliberately removing blood.
The idea came partly from the ancient theory of the four humours: blood, phlegm, yellow bile and black bile. Illness was thought to result from an imbalance between them.
The solution?
Drain some blood.
Bloodletting remained remarkably popular well into the 18th and 19th centuries.
One famous patient was George Washington. When he developed a severe throat illness in 1799, his doctors repeatedly bled him. Over a short period, they removed a substantial proportion of his circulating blood.
Washington died.
His underlying infection was probably serious, so we cannot say bloodletting alone killed him. But losing so much blood certainly wouldn't have helped a critically ill patient.
What medicine learned: A treatment needs evidence that it improves outcomes — not merely a convincing theory explaining why it should work.
2. Ignaz Semmelweis: The Doctor Who Was Right — and Ignored
In the 1840s, Hungarian physician Ignaz Semmelweis noticed something disturbing.
Women giving birth in one maternity clinic were dying from puerperal, or "childbed," fever far more frequently than women in another.
One major difference?
Doctors and medical students often came directly from performing autopsies before examining women in labour.
Semmelweis introduced handwashing with a chlorinated solution.
Mortality fell dramatically.
You might imagine doctors immediately celebrated the discovery.
They didn't.
Many rejected the idea that physicians themselves could be transmitting disease. Germ theory had not yet become established, and Semmelweis struggled to persuade the medical establishment.
Today, hand hygiene is one of the foundations of infection prevention.
What medicine learned: Evidence can be correct even when we don't yet understand the mechanism.
3. Lobotomy: A Nobel Prize-Winning Disaster
Few chapters in medical history are as unsettling as the lobotomy.
In the 1930s and 1940s, doctors began surgically disrupting connections in the frontal lobes of patients with severe psychiatric illnesses.
Portuguese neurologist António Egas Moniz, who developed the leucotomy, was awarded the 1949 Nobel Prize in Physiology or Medicine for the procedure.
The treatment spread rapidly.
Thousands of people underwent versions of psychosurgery. Some became calmer, but others suffered devastating personality changes, cognitive impairment, disability, seizures or death.
As effective psychiatric medications became available, lobotomy largely disappeared from routine practice.
What medicine learned: Making symptoms less troublesome is not necessarily the same as making the patient better.
4. Thalidomide: The Drug That Changed Medicine Regulation
In the late 1950s and early 1960s, thalidomide was marketed in several countries as a sedative and was also used by pregnant women suffering from morning sickness.
Then doctors began seeing babies born with severe congenital abnormalities, particularly dramatically shortened or absent limbs.
Thousands of children worldwide were affected.
The tragedy transformed how medicines are tested and regulated, particularly regarding pregnancy and fetal development.
Interestingly, thalidomide itself did not disappear forever. Under extremely strict controls, it later found legitimate uses in diseases including multiple myeloma.
What medicine learned: A medicine can be relatively safe for one person while being catastrophic for a developing fetus.
5. Radium: When Radioactivity Was Considered Healthy
After radioactivity was discovered, the public became fascinated by it.
During the early 20th century, radioactive materials appeared in an extraordinary range of products. Some were promoted as health treatments or tonics.
One notorious example was Radithor, essentially water containing radioactive radium.
American industrialist Eben Byers reportedly consumed large quantities of it after being advised to use it for an injury.
He eventually developed devastating radiation-related disease and died in 1932.
The publicity surrounding his death helped expose the dangers of radioactive "health" products.
What medicine learned: "New" and "scientific-sounding" do not mean safe.
6. Smoking Was Once Considered Compatible With Good Health
This one feels almost unbelievable today.
During the first half of the 20th century, cigarettes were widely advertised, sometimes using doctors or medical imagery to reassure consumers.
Meanwhile, lung cancer rates were rising.
By the mid-20th century, increasingly powerful epidemiological evidence established the relationship between cigarette smoking and lung cancer, as well as cardiovascular and other diseases.
The medical consensus changed dramatically.
What medicine learned: Some health risks become obvious only when we study very large populations over long periods.
The Bigger Lesson
It's easy to look back and laugh at doctors who prescribed radioactive water or drained blood from sick patients.
But there's a more uncomfortable lesson here.
Those doctors weren't necessarily foolish.
They were practising according to the knowledge, assumptions and evidence available to them at the time.
And that means some things we consider good medicine today may eventually turn out to be ineffective — or even harmful.
That's why medicine must constantly question itself.
Clinical trials, peer review, pharmacovigilance and evidence-based guidelines aren't bureaucratic inconveniences.
They're safeguards built partly from centuries of mistakes.
The most important sentence in medicine may therefore be:
"We could be wrong."
And when better evidence arrives, good medicine changes with it.
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Stay healthy!
👩⚕️ Dr. Joanna
AskADoc4Advice — where medicine meets curiosity (and a little bit of weird).
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