Heroes don't usually make you bleed or vomit. You'll never see Superman fight evil doers by lancing someone or forcing large doses of calomel down Lex Luther's throat.
And yet "heroic" was what medicine in the 18th and 19th centuries was called. At least the medicine practiced by so-called "regular" doctors through at least the mid-19th century (those who didn't practice heroic medicine were known as alternative or sectarian practitioners--or in unkinder moments, quacks).
Heroic medicine consisted of bleeding, purging, leeching, blistering, and sweating patients to release disease. Calomel, mercurous chloride, was one of the most commonly used mineral concoctions, a harsh treatment that would induce vomiting and purging. At the time, most diseases were seen as systemic imbalances caused by something being either over- or under-stimulated in the body. Until the 1840s, most doctors believed that diseases overstimulated the body so most treatments involved lowering the overexcited patient back to a normal, healthy state. Bleeding often became the first "therapeutic" line of attack, being a seemingly easy way to get whatever disease was poisoning the system and knocking it out of balance back into place.
Heroic medicine gave clear evidence that it worked. Or at least that the treatment was doing something--and that something was often healing in of itself. People felt better just knowing that they were being treated, even if that treatment could sometimes kill them. It also gave the doctor the appearance of being in control of the situation. There's just something about doing that feels a whole lot better than waiting and watching for nature to run its course, as it often does in disease. The body is an amazing healing machine.
So why heroic? The word apparently comes from the large dosage size and effect of the therapies. They didn't just give you a bit of calomel. They gave you A LOT to produce a near instantaneous effect--which, in this instance, was mostly a lot of vomiting. According to the dictionary, "heroic" is "behavior that is bold and dramatic." These treatments certainly were bold and the results often dramatic if not always healing.
But they were also rather harsh and public outcry against them helped lead to their demise in the 19th century.