Constipated? In the early 19th century, the apothecary would most likely have prescribed you calomel, or mercurous chloride, as a purgative, regardless of its toxicity. Because it worked. It was also useful as an insecticide.
This was the sort of thing being concocted at the Apothecaries’ Hall in Blackfriars, then a major center for drug manufacturing in London, says Anna Simmons, a historian of science at the Open University in Milton Keynes. It was also common for patients with chronic skin infections to walk away with a dose of arsenic, she says.