During the Baroque era, doctors used bloodletting to treat everything from fevers to heartbreak.

The practice of bloodletting was rooted in the humoral theory established by Hippocrates and expanded by Galen in the 2nd century AD. This system claimed the body was governed by four fluids: blood, phlegm, yellow bile, and black bile. An imbalance, particularly an excess of blood known as 'plethora,' was thought to trigger physical disease and psychological instability.Physicians used various tools for the procedure, including leeches for localized issues and 'fleams' or 'lancets' for systemic draining. During the 17th and 18th centuries, the procedure reached its peak in popularity. For example, in 1685, King Charles II of England was subjected to the removal of approximately 710 milliliters of blood by his royal physicians following a seizure, a treatment that likely hastened his demise.The danger of this practice is best illustrated by the death of George Washington in 1799. To treat a severe throat infection, doctors drained nearly 3.75 liters of his blood, which represented about 40% of his total blood volume, within just 24 hours. This massive loss of fluid caused hypovolemic shock and ultimately led to his death.Despite its lethality, bloodletting remained a standard medical practice for nearly 2,000 years. It only began to decline in the mid-1800s after French physician Pierre Louis conducted 'numerical method' studies. His research proved that pneumonia patients who underwent bloodletting had higher mortality rates than those who did not, finally ushering in the era of evidence-based medicine.