Touted as a treatment for everything from syphilis to tuberculosis to constipation, mercury was a go-to drug in the 1800s. Abraham Lincoln took mercury-laden blue pills for “melancholy,” but stopped them in 1861 because he believed they were linked to his violent rages. In 2010, the pills were discovered in a museum and analyzed by the Royal Society of Chemistry. The result showed Lincoln’s daily dosage of blue pills contained up to 120 times the maximum limit of mercury intake that the World Health Organization deems safe. Elemental mercury poisoning can cause insomnia, emotional changes, and poor cognitive function.