A simple mix of salt, sugar and clean water has saved millions of children.
Oral rehydration solution was developed and tested in the 1960s, including at the cholera research laboratory in Dhaka. Glucose helps the gut absorb salt and water, reversing dehydration.
Why it matters: It is cheap, can be given at home, and remains a frontline treatment for diarrhoea worldwide.
One medical textbook was studied for centuries across two continents.
Ibn Sina completed al-Qanun fi al-Tibb in 1025, organising knowledge of diseases, drugs and diagnosis. Translated into Latin, it was taught in European universities for centuries.
Why it matters: Its rules for testing medicines carefully foreshadowed modern clinical trials.
The Canon of Medicine (al-Qanun fi al-Tibb) — Ibn Sina (Avicenna) (1025)
Washing hands once cut deaths on a hospital ward dramatically.
In 1847 Ignaz Semmelweis made doctors in Vienna wash their hands in chlorinated lime before delivering babies. Deaths from childbed fever on his ward fell sharply.
Why it matters: Handwashing is still one of the simplest ways to stop infection spreading.
The Etiology, Concept and Prophylaxis of Childbed Fever — Ignaz Semmelweis (1861) Handwashing introduced at Vienna General Hospital, 1847
A plate left out on a lab bench led to the first antibiotic.
In 1928 Alexander Fleming noticed a mould had killed the bacteria around it on a culture plate. Howard Florey and Ernst Chain later turned penicillin into a usable medicine.
Why it matters: Antibiotics have saved millions of lives — which is why they must not be misused.
On the antibacterial action of cultures of a penicillium — Alexander Fleming (1929) British Journal of Experimental Pathology, 1929; Nobel Prize 1945
A disease caught by milkmaids led to the first vaccine.
Edward Jenner noticed milkmaids who caught cowpox seemed protected from smallpox. In 1796 he inoculated a boy with cowpox and showed he was then protected. He published in 1798.
Why it matters: Vaccination eventually wiped out smallpox; the WHO declared it eradicated in 1980.
An Inquiry into the Causes and Effects of the Variolae Vaccinae — Edward Jenner (1798)