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Sulfa drugs
1935 (Prontosil, Domagk)· Invention or discovery· Germs, drugs & genetics
Well documentedSolid records, physical evidence or scientific consensus.
Sulfa drugs, starting with Bayer's red dye Prontosil, were the first medicines to cure a wide range of bacterial infections inside the body.
See it on the Technology & Medicine map →How it works
At Bayer in Germany, Gerhard Domagk screened dyes for germ-killing power and in 1932 found that Prontosil protected mice from streptococcus. Published in 1935, it soon saved patients, reportedly including his own daughter. Researchers at the Pasteur Institute in Paris then showed the body breaks Prontosil down into sulfanilamide, a cheap, unpatentable compound that does the real work. Sulfa drugs block bacteria from making folic acid, a vitamin they need to grow.
Why it mattered
They cut deaths from childbirth fever, pneumonia and wound infections. A 1937 US poisoning disaster from one sulfa syrup led to modern drug-safety law in 1938.
How we know
Domagk's 1935 paper, the Pasteur Institute studies and hospital death statistics. Domagk won the 1939 Nobel Prize, which the Nazi government forced him to decline.
Still unknown or debated
Economists still estimate how much of the 1930s drop in maternal and pneumonia deaths came from sulfa drugs versus better care and nutrition.
Connections (3)
▸Salvarsan, the first 'magic bullet' inspired the chemical search that found Sulfa drugsWell documented
The connection
Paul Ehrlich found Salvarsan by testing hundreds of synthetic compounds, number 606 being the winner, for one that killed the syphilis germ. Domagk used the same approach at Bayer, screening thousands of dyes in infected mice until Prontosil worked in 1932. Ehrlich's idea that dyes could target germs selectively guided both.
When and how
Frankfurt, 1909–10 (Ehrlich and Sahachiro Hata); Bayer's laboratories at Elberfeld, Germany, then part of IG Farben, 1927–35 (Domagk).
How we know
Domagk's program was explicitly modeled on Ehrlich's dye-screening chemistry; both grew from Germany's dye industry, as company and lab records show.
Debates and open questions
Prontosil works only after the body breaks it down; whether Bayer's chemists missed, or kept quiet, that the cheap breakdown product was the real drug is debated.
▸Sulfa drugs were overtaken by Penicillin and antibioticsWell documented
The connection
Sulfa drugs proved that chemicals could cure infections inside the body, reviving interest in Fleming's neglected penicillin. Penicillin, purified from 1940, killed bacteria rather than just halting their growth, worked on more infections and was less toxic. By the late 1940s it had replaced sulfa drugs for most uses.
When and how
Germany and France, 1935–36 (sulfa drugs); Oxford, 1939–41 (Florey, Chain, Heatley); US mass production, 1943–45.
How we know
Historians such as John Lesch show that sulfa's success made drug cures credible and research fundable; wartime medical records show the switch.
Debates and open questions
Sulfa drugs never vanished: combinations such as trimethoprim-sulfamethoxazole are still widely used, so 'overtaken' describes most uses, not all.
▸Aspirin came from the Bayer labs that later found Sulfa drugsWell documented
The connection
Bayer grew from a dye maker into a drug company, and aspirin's success helped make it a research powerhouse. Its labs screened thousands of dyes in animals. There, in 1932, Gerhard Domagk found that the dye Prontosil cured streptococcal infections in mice: the first sulfa drug, and the first broad antibacterial. Bayer was by then part of IG Farben.
When and how
Bayer's labs in Elberfeld (now Wuppertal), Germany: aspirin in 1897; Prontosil, made by chemists Josef Klarer and Fritz Mietzsch, tested in 1932 and published in 1935.
How we know
Company lab records, Domagk's 1935 paper, and his 1939 Nobel Prize, which the Nazi government forced him to decline at the time.
Debates and open questions
In 1935 Pasteur Institute scientists showed Prontosil's active part was sulfanilamide, an old, unpatentable chemical; whether the company knew this earlier is debated.