1796 Edward Jenner develops a method to protect people from smallpox by exposing them to the cowpox virus. In his famous experiment, he rubs pus from a dairymaid's cowpox postule into scratches on the arm of his gardener's 8-year-old son, and then exposes him to smallpox six weeks later (which he does not develop). The process becomes known as vaccination from the Latin vacca for cow. Vaccination with cowpox is made compulsory in Britain in 1853. Jenner is sometimes called the founding father of immunology.
1800 Sir Humphry Davy announces the anesthetic properties of nitrous oxide, although dentists do not begin using the gas as an anesthetic for almost 45 years.
1816 René Laënnec invents the stethoscope.
1818 British obstetrician James Blundell performs the first successful transfusion of human blood.
1842 American surgeon Crawford W. Long uses ether as a general anesthetic during surgery but does not publish his results. Credit goes to dentist William Morton.
1844 Dr. Horace Wells, American dentist, uses nitrous oxide as an anesthetic.
1846 Boston dentist Dr. William Morton demonstrates ether's anesthetic properties during a tooth extraction.
1849 Elizabeth Blackwell is the first woman to receive a medical degree (from Geneva Medical College in Geneva, New York).
1867 Joseph Lister publishes Antiseptic Principle of the Practice of Surgery, one of the most important developments in medicine. Lister was convinced of the need for cleanliness in the operating room, a revolutionary idea at the time. He develops antiseptic surgical methods, using carbolic acid to clean wounds and surgical instruments. The immediate success of his methods leads to general adoption. In one hospital that adopts his methods, deaths from infection decrease from nearly 60% to just 4%.
1870s Louis Pasteur and Robert Koch establish the germ theory of disease. According to germ theory, a specific disease is caused by a specific organism. Before this discovery, most doctors believe diseases are caused by spontaneous generation. In fact, doctors would perform autopsies on people who died of infectious diseases and then care for living patients without washing their hands, not realizing that they were therefore transmitting the disease.
1879 First vaccine for cholera
1881 First vaccine for anthrax
1882 First vaccine for rabies
1890 Emil von Behring discovers antitoxins and uses them to develop tetanus and diphtheria vaccines.
1895 German physicist Wilhelm Conrad Roentgen discovers X rays.
1896 First vaccine for typhoid fever.
1897 Ronald Ross, a British officer in the Indian Medical Service, demonstrates that malaria parasites are transmitted via mosquitoes, although French army surgeon Charles Louis Alphonse Laveran identified parasites in the blood of a malaria patient in 1880. The treatment for malaria was identified much earlier (and is still used today). The Qinghao plant (Artemisia annua) was described in a Chinese medical treatise from the 2nd century BCE; the active ingredient, known as artemisinin, was isolated by Chinese scientists in 1971 and is still used today. The more commonly known treatment, quinine, was derived from the bark of a tree called Peruvian bark or Cinchona and was introduced to the Spanish by indigenous people in South America during the 17th century.
1897 First vaccine for plague.
1899 Felix Hoffman develops aspirin (acetyl salicylic acid). The juice from willow tree bark had been used as early as 400 BC to relieve pain. 19th century scientists knew that it was the salicylic acid in the willow that made it work, but it irritated the lining of the mouth and stomach. Hoffman synthesizes acetyl salicylic acid, developing what is now the most widely used medicine in the world.
1901 Austrian-American Karl Landsteiner describes blood compatibility and rejection (i.e., what happens when a person receives a blood transfusion from another human of either compatible or incompatible blood type), developing the ABO system of blood typing. This system classifies the bloods of human beings into A, B, AB, and O groups. Landsteiner receives the 1930 Nobel Prize for Physiology or Medicine for this discovery.
1906 Sir Frederick Gowland Hopkins suggests the existence of vitamins and concludes they are essential to health. Receives the 1929 Nobel Prize for Physiology or Medicine.
1907 First successful human blood transfusion using Landsteiner's ABO blood typing technique
1913 Dr. Paul Dudley White becomes one of America's first cardiologists, a doctor specializing in the heart and its functions, and a pioneer in use of the electrocardiograph, exploring its potential as a diagnostic tool.