How do you treat dysentery in the 1800s on the Oregon trail?

It’s hard for modern people to believe, but in the mid-1800s medical practice had much more in common with religion than science. Microbes were completely undreamed-of, and no one knew why people got sick; so everything from “too much blood” to the vengeance of an angry god got blamed for things like cholera and malaria. And, as is the case with religious instruction, followers of particular “sects” could get pretty fierce with one another.

Of course, the Native Americans had their own healing traditions, many of which are now lost. But back when the United States was founded, European medicine was still mired in the imagineerings of Galen, a Roman physician from the second century A.D. who claimed that a balance of “humours” – blood, phlegm, “black bile” and “yellow bile” – was the key to wellness, and that all sickness stemmed from an imbalance in these four simple things. To cure disease, one simply had to restore that balance by various combinations of bleeding and purging.

By the time the Lewis and Clark expedition showed up in Oregon back in 1805, European medicine had barely moved from this position. The main innovation had been a sort of mania for “heroic” application of the bleedings and purgings – forcing already-sick people to endure the loss of pints of blood and spend hours straining and retching over chamber-pots and outhouses. Naturally, this abuse killed plenty of people who otherwise would have survived. Everyday people had started to notice this, and the respectability of mainstream medicine was probably at its lowest ebb.

The dreaded final screen of the Oregon Trail videogame as rendered on an early-1980s-vintage Apple IIe computer.
And that was the kind of medicine that was being practiced by the members of the Lewis and Clark expedition, on its way to Oregon. Prominent in the voyagers’ first-aid kit were hundreds of beefy white tablets of mercury chloride, marketed as “Dr. Rush’s Bilious Pills” – a concoction of American founding father Dr. Benjamin Rush, a signer of the Declaration of Independence.