Was Bloodletting Effective?
Bloodletting was effective in ending a disease process. However, studies show that most people died after bloodletting perished due to diseases that were incurable in their time, so bloodletting probably didn’t help. There are several conditions that bloodletting may have helped, but studies show that any improvement was not from balancing the body’s humors.
Studies discovered that positive effects after bloodletting probably came from reducing blood volume or harmful components in the blood that had accumulated in the body. For instance, high blood pressure [1] may have been temporarily used in some cases of bloodletting, simply because of the reduction of blood volume. While this fix may not be life-threatening, it would not last long.