What were the main uses for leeches in medicine?

Leeches were commonly used in medicine for bloodletting, a practice believed to balance the four humors and treat various illnesses. They were also used to remove toxins from the body, promote healing and relieve symptoms such as headaches, skin diseases, and fevers. Leeches were also thought to have anti-inflammatory properties and were used in surgeries to reduce swelling and improve blood circulation.