• Weird History

Major Medical Discoveries That Happened By Mistake

List RulesVote up the most surprising accidental medical discoveries.

Every year, millions of hours and billions of dollars are poured into medical innovation, with new methods of improving, sustaining, and extending human life discovered on a near daily basis - yet without some significant accidental medical discoveries thrown into the mix, many of us would not be here today.

Unintended scientific discoveries often prove more fascinating than those made on purpose. Perhaps it’s the lure of serendipity, or the enticing possibility of changing the world for the better through nothing more than sheer happenstance. Either way, people everywhere are grateful that some enterprising individuals were fortunate enough to stumble into important medical breakthroughs - and had awareness enough to understand the implications of their discoveries. 

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    Penicillin Was Discovered When A Scientist Decided Not To Throw Out A Moldy Petri Dish

    The discovery of penicillin has made an enormous impact on the world, and is perhaps the most famous tale of accidental medical innovation in history - even if the commonly told version of the tale is a touch apocryphal. Alexander Fleming did not, as is commonly reported, leave a sandwich or some other item sitting in his lab while on vacation, only to return and find it molded over with a life-saving substance, but the truth is not far off.

    Fleming did go on vacation in 1928, and he did leave some items out in the lab, but they were Petri dishes filled with colonies of Staphylococcus. When he returned, he started examining them, including one that had grown moldy in his absence - and that’s when he made the discovery of a lifetime. The area of the dish affected by the mold, which Fleming later identified as Penicillium notatum, was free of the Staphylococcus, as if something in the mold itself was inhibiting the growth and spread of the bacteria. Soon enough, Fleming proved that that was exactly what was happening, and as a result penicillin is now the most widely used antibiotic in the world. 

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  • Photo: C. Manigaud/E. Hamman / Wikimedia Commons / CC BY-SA 3.0
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    Vaccinations Were Discovered Because A Milkmaid Told A Scientist People Who Got Cowpox Didn’t Get Smallpox

    It’s arguable that no medical discovery in all of human history has had a greater impact than the mechanism behind vaccinations. The discovery came not from a lab or a university, however, but from an ordinary farm and the musings of a milkmaid, along with a doctor willing to listen.

    Edward Jenner was not the first person in history to experiment with inoculation, but he is the most noteworthy and is widely recognized as the originator of vaccines. When he was still a teenager in the 1760s, a woman told him, “I shall never have smallpox for I have had cowpox. I shall never have an ugly pockmarked face” - and that stuck with him. 

    It wasn’t until 1796, after a lengthy career as a medical researcher, that Jenner finally applied this knowledge. He found another milkmaid, Sarah Nelms, who had been freshly infected with cowpox, and used material from her lesions to inoculate a young boy. When the boy proved immune to smallpox, the era of vaccines had officially begun - and the source of smallpox was well on its way to being eliminated.

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  • Photo: Audrey Disse / Wikimedia Commons / CC BY-SA 3.0
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    Viagra Was Developed To Treat High Blood Pressure, Then Nurses Noticed A Peculiar Side Effect

    In the early 1990s, researchers at Pfizer were looking into a substance known as sildenafil as a potential treatment for high blood pressure, reasoning that it might be able to dilate the heart’s blood vessels by blocking a certain protein. When initial tests looked promising, they moved on to human trials, which yielded mostly disappointing results - save for one weird quirk.

    Nurses examining test subjects noticed that the men who had ingested the substance were often lying on their stomachs when they came into the room to check on them. One nurse quickly figured out that the men were embarrassed by their uncontrollable erections, a side effect of sildenafil that is now considered its primary purpose - under the new name of Viagra, of course. 

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  • Photo: Dr. Roshan Nasimudeen / Wikimedia Commons / CC BY-SA 3.0
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    The Pap Smear As A Way To Test For Cancer Was Discovered During A Study Of Changes During The Course of Sexual Development

    The Pap smear is one of the simplest procedures in modern medicine, yet one of the most vital for maintaining female health. It all stems from one doctor, George Papanicolaou, and his desire to understand the menstrual cycle. 

    At first, Papanicolaou only intended to swab his test subjects’ vaginas to determine how their vaginal cells changed at different stages of sexual development. But when he noticed cancer cells in one such swab, the focus of his research shifted - and he soon discovered that this simple, inexpensive procedure provided the earliest possible indications of cervical cancer in patients. In doing so, Papanicolaou undoubtedly saved countless lives, and today the method still bears his mercifully shortened name. 

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