Rise to popularity and early criticism

During the 19th century homeopathy grew in popularity. In 1830, the first homeopathic schools opened, and throughout the 19th century dozens of homeopathic institutions appeared in Europe and the United States.^[55] Because of mainstream medicine's reliance on blood-letting and untested, often dangerous medicines, patients of homeopaths often had better outcomes than those of mainstream doctors.^[56] Homeopathic treatments, even if ineffective, would almost surely cause no harm, making the users of homeopathic medicine less likely to be killed by the medicine that was supposed to be helping them.^[1] The relative success of homeopathy in the 18th century may have led to the abandonment of the ineffective and harmful treatments of bloodletting and purging and to have begun the move towards more effective, scientific medicine.^[40]

In the early 19th century, homeopathy began to be criticised. Sir John Forbes, physician to Queen Victoria, said the extremely small doses of homeopathy were regularly derided as useless, laughably ridiculous and "an outrage to human reason".^[57] Professor Sir James Young Simpson said of the highly diluted drugs: "No poison, however strong or powerful, the billionth or decillionth of which would in the least degree affect a man or harm a fly."^[58] Nineteenth century American physician and author Oliver Wendell Holmes, Sr. was also a vocal critic of homeopathy and published an essay in 1842 entitled Homœopathy, and its Kindred Delusions.^[59] The last school in the U.S. exclusively teaching homeopathy closed in 1920.^[1]